(L‘ ‘ ,,:.. w. r” .I t ' I 1‘, x v ’ 'l‘mh’. A. ' . n.» .x '3 l w :35: "‘9' 7"; n , 4.": . ‘ ...-. a-r-v. nvo -1. ~ '1‘] -=‘p. _, f'ff‘fu“ ;. .1 'fr 3: - , k‘ . ’~ a ‘9: . Luci . -\ Vt ‘ 1 ..\: §_ . . ’ ‘ ‘A r}"""EP'~ ,. ?:“k . ,3» ,4... ”a“. rwmr'r‘ “P u, »,.~.ar v - ', 34-3. 4.. . :2 :5 W?! 1531 diiiléx ’3‘;th nil“ ’ \TTNYTT\\T\\\\\ \\ \\\\\\\\\\\\\\\\\i g,- ' NYWHVS This is to certify th at the dissertation entitled SOFT WHEAT QUALITY FACTORS THAT INFLUENCE THE QUALITY CHARACTERISTICS OF EGYPTIAN BALADY BREAD presented by SAMIR MOHAMED HUSSEIN RABIE has been accepted towards fulfillment of the requirements for Ph.D. degreein Food Science L/O/Major pgessor DateflZLU/K; M7 :2. MS U is an Affirmative Action/Equal Opportunity lnuitution 0-12771 LIBRARY Michigan State University PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before duo duo. DATE DUE DATE DUE DATE DUE MSU Is An Affirmative Action/Equal Opponunny Institution \ cm.m3-o.1 SOFT WHEAT QUALITY FACTORS THAT INFLUENCE THE QUALITY CHARACTERISTICS OF EGYPTIAN BALADY BREAD By: SAMIR MOHAMED HUSSEIN RABIE A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Food Science and Human Nutrition 1992 ,,/g, 77/ / 5'7 ’ ABSTRACT SOFT WHEAT QUALITY FACTORS THAT INFLUENCE THE QUALITY CHARACTERISTICS OF EGYPTIAN BALADY BREAD By: SAMIR MOHAMED HUSSEIN RABIE Flour quality parameters which contribute desirable characteristics to Egyptian Balady bread were determined. Eight soft winter wheat varieties were selected and milled into 90% extraction flours. These flours were evaluated for their composition, alkaline water retention capacity and dough properties. Optimum water absorptions of these flours for*making Balady bread were determined subjectively and the corresponding mixing times were determined objectively using the mixograph. The breads were evaluated subjectively for their top and bottom layer, interior, aroma, taste, and chew attributes. The sum of panelists' scores of these attributes for each breed was considered as an index for quality. The breads were also evaluated objectively for layer thickness, texture, and color. Sensory data showed significant differences among breads for all attributes except taste. All breads were scored acceptable or better. Top as well as bottom layers of all breads showed similar thickness and texture except that Hillsdale bread was slightly tougher than that of Tecumseh. Color measurements of bread exterior surfaces varied among varieties and associated with flour type. The farinograph and. mixograph studies were conducted at the standard AACC and the baking absorptions and reflected some differences among flours. The back extrusion was used, for the first time, to evaluate the soft wheat flour-water doughs. Differences among doughs and among shear rates were noted. Dough viscosity index and apparent SAMIR MOHAMED HUSSEIN RABIE elasticity as well as curve heights and areas of the peak and of 30 seconds after the peak correlated with mixograph measurements. Linear regression analysis indicated that flour protein content and farinograph mixing tolerance index and arrival time associated with 98.5% of the variation in baking water absorption among flours. About 98% of the variation in baking mixing time can be explained by a model containing the farinograph stability time, uuxograph area and either farinograph arrival time or back extrusion percent drop in curve height 30 seconds ‘ shear rate. after the peak using 3.14 sec“ The scanning'electron.microscopy study of the flour-water doughs and Balady breads showed ultrastructural variations among varieties. Differences were noted and were related to dough measurements and bread quality. Copyrighted by SAMIR MOHAMED HUSSEIN RABIE 1992 ACKNOWLEDGMENTS I wish to extend sincere thanks to my major professor Dr. M. E. Zabik for her guidance and support through out this project and during writing the thesis manuscript. Thanks are also extended to Drs. K. Klomparens, M. Uebersax, B. Hart, and D. Smith for serving on the guidance committee. The author is indebted. to the U.S. Agency For International Development for providing the sponsorship during the first two years of this project, and to Dr. M. E. Zabik, Dr. I. J. Gray and Mrs. 8. Cash for providing research and teaching assistantships during parts of this project. The author is also indebted to Drs. E. Everson, D. Glenn, and N. Wassimi of Crop and Soil Sciences Dept., Michigan State University for supplying wheat samples and related information, to Dr. P. Finney, L.C. Andrews, and Dr. J. R. Donelson of the Soft Wheat Quality Lab., Wooster, 08 for milling wheat samples, measurements of flour damaged starch, and supplying related information, to Dr. G. Rubenthaler of Washington State University, Pullman, WA for his valuable guidance during preparation of the baking oven, to Dr. J. Gill of the Animal Science Dept., Michigan State University for his invaluable statistical guidance, and, to Dr. S. Flegler of the Center of Electron Optics for providing the facilities and valuable guidance. Thanks are extended totother individuals who have contributed to the success and completion of this project: Drs. J. Harte, K. Mackey, C. Lever, and M. Abouelseoud, and S. Selem, and, M. Weaver, M. Nettles, S. El-Toney, J. Dawson, S. Mart, C. Bergman, and s. Daubenmire. The author is very grateful to the Egyptian community in E. Lansing, MI and to his family for their love, support and constant encouragement. iv TABLE OF CONTENTS L18! ' or ms O O O O O O O O O O O O O O O O O L!” or 'Ims O O O O O O O O O O O O O O O O O Imonua I M O O O O O O O O O O O O O O O REVIEW OF LITERATURE . . . WHEAT FLOUR QUALITY AND COMPOSITION . Quality Aspects of Wheat Flour Flour Composition . . . . . . Flour Proteins . . . Flour Carbohydrates . Flour Lipids . . . . Flour Ash . . . . . . Vitamins Content . . Mineral Content . . . Dough Rheological Characteristics The Farinograph Test . . . . The Mixograph Test . . . . . The Extensigraph Test . . . . The Alveograph Test . . . . . The Oscillatory and Viscometry Tests The Back Extrusion Test . . . . . . . Balady Bread Characteristics and Evaluation Wheat Classes and Extraction Rates . Balady Bread Making Process . . . . . Subjective Evaluation . . . . . Objective Evaluation . . . . . Ultrastructure of Dough and Bread Systems . Scanning electron microscopy (SEM) of Scanning electron microscopy of bread Transmission electron microscopy of do Transmission electron microscopy of br “es-see geeeeeeeees eeefleeeeeeeeee sr u nd METHODS AND MATERIALS . . . . . . . . . . Experimental Design . . . . . . . Wheat Source and Flour Preparation The Milling Process . . . . Rheological Study Methods . . . Parinograph studies . . . Mixograph Studies . . . . Back-extrusion study . . Dough preparation fo 1‘ eeeffeeeee e e e do e e s e e e e D D's e e as e e e e e e e he 0 k-e Testing procedure . Baking of Balady Bread . . . . Baking Procedure . . . . . . Preparation of Bread Samples f r O jec Subjective Evaluations . . . Sensory Evaluation . . . . . . . . The Scanning Electron Microscopy Study . . Preparation of Dough Samples . . . . Preparation of Bread Samples . . . . Method #1 . . . . . . . . . . . emen eeeeeeeeeeeefleeeeseeeee I dough structure . . ugh structure ead structure xtrusi tiv structur 3 fl eeeaeeeeeeee . eeeffeeeeeeee O D D. eeeeeeaeeeOeeeeeeee Page viii xi Method #2 . . . . . . Chemical Analyses of Flour and Bread Samples . . . Damaged Starch . . . Alkaline Water Retention Capacity (AWRC) of El Samples . . . . . . . Total Pentosans of Wheat Flour. Samples . Moisture Content . . . . . Protein Content . . . . . . . . Crude Fat Content . . . . . Ash Content . . . . . . . Total Dietary Fiber Content . . . Physical Measurements of Balady Bread . . . Thickness of Balady bread Top and Bottom Layers Texture of Balady Bread Layers "Puncture Test” Color of Balady Bread Top and Bottom Layers . Statistical Designs . . . . . . . . . . Complete Randomized Design (CRD) . . . . Complete Block Design (CBD) . . . . , Balanced Incomplete Block Design (BIBD) . O O“ O O O O O O O O O Split-plot Design (SPD) . . . Development of the Prediction Equations sssesssssesssesseness O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O RESULTS AND DISCUSSION . . . . . . . Milling Data of the Eight Soft Winter Wheat Varieties Flour Composition . . . . . . . . . . Proximate Analyses of the Eight SWW Plours Protein contents . . . . Total dietary fibers (TDF) . Ash contents . . . . . . . . Lipid contents . . . . . . . . Total carbohydrate contents Damaged Starch, AWRC, and Pentosan Content Damaged starch . . . . . . Alkaline water retention capacity (AWRC) Pentosan contents . . . . . . . . . . . . Rheological Study . . . . . . . . . . . . . . . . . Measurements of Dough Properties Using Conventiona 1 Techniques . . . . Parinograph test using the standard AACC procedure . . . . . . . . . . . . Mixograph test using the standard AACC procedure . . . . . . . . . . . . . . . . Measurements of Dough ProPerties Using Unconventional Techniques . . . . . . Parinograph study at Balady bread baking absorptions . . . . . . . Mixograph study at Balady bread baking absorption . . . . . Mixograph study at 60, 65, and 70% water. absorption . . . . . . . Measurements of dough properties using the back- extrusion . . . . . . . . . . Subjective and Objective Evaluation of .Balady Bread Made from the Eight SWW Plours . . . Subjective Evaluation of Balady Bread . Objective Evaluation of Balady Bread . Bread layer thickness . . . . . . Texture of bread layers . . . . . Color of bread crusts . . . . . . L values (Degree of lightnes ) O O O O O O O vi O O O O O O O O O O O O O O O O O Page 74 74 75 75 76 76 76 76 76 77 77 77 77 78 79 79 80 81 83 85 86 86 88 88 9O 91 91 91 91 93 93 94 95 95 95 100 106 106 112 116 128 148 149 153 153 155 155 155 a values (degree of redness) . . b values (degree of yellowness) . Proximate chemical analyses of Balady bread . Prediction Equations for Balady Bread Optimum Baking Water Absorption, and Mixing Time . . . 1. Prediction of baking water absorption (WA) Balady bread . . . . . 2. Prediction of baking mixing time of Balady Ultrastructure Study of Dough and Bread Systems . . Flour-water dough systems . . . . . . . . . . Balady bread systems . . . . . . . . . . . . M! m mans I m O O O O O O O O O O O O O O O O O RECOMMENDATIONS FOR FUTURE RESEARCH . . . . . . . . . . . “mas O O O O O O O O O O O O O O O O O O O O O O O APPENDICES APPENDIX A . . . . . Balady Bread Description Sheet . APPENDIX B . . . . . . . . . . . . . Balady Bread Score Card . . . . . APPENDIX C . . . . . UCRIMS Approval of the Sensory Tests . APPENDIX D . . . . . . . . . . . . . . . . . Analyses of Variance and Simple Correlat o assesses i n vii of bread Page 158 159 160 164 165 165 167 167 176 192 202 204 213 213 214 214 215 215 216 LIST OF TABLES Table 1 Some Agronomical Data of the Eight Winter Soft Wheat vari.t i.‘ O O O O O O O O O O O O O O O O O O O O O O O 2 Wheat Kernel Protein, Growing Locations, Locations Contributed to the Varietal Blend, and, Moisture and Total Weight of the Blend of the Eight Soft Winter Wheat variet 1°! O O O O O O O O O O O O O O O O O O O O O O O 3 Milling Data of the Eight Soft Winter Wheats . . . . . . . 4 Levels of Water Absorption and Mixing Time Used in Balady Dough Preparation for Baking of the Eight SWW Flours . . 5 Proximate Analysis Data (d.b.) of the Eight Soft Winter Wheat Flours of 90% Extraction . . . . . . . . . . . . . 6. Damaged Starch, Alkaline Water Retention Capacity, and Pentosan Content of the Eight Soft Winter Wheat Plours . 7 Parinograph Data of the Flour-water Doughs (Standard AACC Procedure) of the Eight Soft Winter Wheat Varieties . . 8 Mixograph Data of the Flour-water Doughs (Standard AACC Procedure) of the Eight Soft Winter Wheat Varieties . . 9 Parinograph Data of the Flour-water Doughs Mixed at Balady Bread Baking Absorption . . . . . . . . . . . . . . . . 10 Mixograph Data of the Flour-water Doughs Mixed at Baking Absorpt ion O O O O O O O O O O O O O O O O O O O O O O O 11 Peak Time (min) of the Mixograms of the Eight Soft Winter Wheat Flour-water Doughs Prepared with 60, 65, and 70% . water Absorpt ion. O O O O O O O O O O O O O O O O O O O 12 Peak Height (M.U.) of the Mixograms of the Eight Soft Winter Wheat Flour-water Doughs Prepared with 60, 65, and 70% Water Absorptions . . . . . . . . . . . . . . . . . 13 Height at 8 min (M.U.) of the Mixograms of the Eight Soft Winter Wheat Flour-water Doughs Prepared with 60, 65, and 70% Water Absorptions . . . . . . . . . . . . . . . . . 14 .Area Under Curve (cmz) of the Mixograms of the Eight Soft Winter Wheat Flour-water Doughs Prepared with 60, 65, and 70% Water Absorptions . . . . . . . . . . . . . . . . . 15 Slope (Newton/mm) of Back Extrusion Curve at Three Shear rates of the Eight Soft Winter Wheat Flour-water Doughs 16 Comparison between Means of the Three Shear Rates of the Back Extrusion Data of the Eight SWW Wheat Doughs . . . 17 Peak Height (Newton) of Back Extrusion Curve at Three Shear rates of the Eight Soft Winter Wheat Flour-water Doughs viii Page 58 59 62 69 89 92 97 102 109 114 118 121 123 126 131 132 134 Table Page 18 Peak Area (Newton mm) of Back Extrusion Curve at Three Shear Rates of the Eight Soft Winter Wheat Flour-water Dough: O O O O O O O O O O O O O O O O O O O O O O O O O 13 6 19 Height (Newton) at 30 sec after the Peak of Back Extrusion at Three Shear Rates of the Eight Soft Winter Wheat Flour-water Dough. O O O O O O O O O O O O O O O O O O O O O O O O O 138 20 Curve Area (Newton mm) of 30 sec after Peak of Back Extrusion Curve at Three Shear Rates of the Eight Soft Winter Wheat Flour-water Dough. e e e e e s s s e e e e s e e e e s s 142 21 Relaxation Time (sec) at Three Shear Rates of Back Extrusion of the Eight Soft Winter Wheat Flour-water Dough. O O O O O O O O O O O O O O O O O O O O O O O O O 143 22 Viscosity Index (poise) at Three Shear Rates of Back Extrusion of the Eight Soft Winter Wheat Flour-water Doughs O O O O O O O O O O O O O O O O O O O O O O O O O 144 23 .Apparent Elasticity (Newton/cmz) at Three Shear Rates of Back Extrusion of the Eight Soft Winter Wheat Flour-water Dough. O O O O O O O O O O O O O O O O O O O O O O O O O 146 24 Sensory Data of Balady Bread Baked from the Eight Soft Wh..t Flour' O O O O O O O O O O O O O O O O O O O O O O 150 25 Layer Thickness (mm) of Balady Bread Baked from the Eight Soft Winter Wheat Plours . . . . . . . . . . . . . . . . 154 26 Puncture Curve Area and Maximum Force of Balady Bread Baked from the Eight Soft Winter Wheat Flours . . . . . . . . 156 27 Color Measurements of Balady Bread Top and Bottom Crusts Baked from the Eight SWW Flours . . . . . . . . . . . . 157 28 Proximate Analysis Data of Balady Bread (d.b.) Baked from the Eight Soft Winter Wheat Varieties . . . . . . . . . . . 161 29 Percent Change (d.b.) in the Major Components of the Bread in Comparison with those in the Corresponding Flour . . 163 30 Analyses of Variance- Completely Randomized Design for Flour Contents of Protein, Total Dietary Fiber (TDF), Ash, Lipids, and Damaged Starch . . . . . . . . . . . . . . . 216 31 Analyses of Variance- Complete Block Design for Flour Alkaline Water Retention Capacity (AWRC) and Total Pentosan Content . . . . . . . . . . . . . . . . . . . . . 217 32 Analyses of Variance- Completely Randomized Design for Parinograph Measurements (Standard AACC Procedure) . . . 218 33 Analyses of Variance- Completely Randomized Design for Mixograph Measurements (Standard AACC Procedure) . . . . 219 34 Analyses of Variance- Completely Randomized Design for Parinograph Measurements (At Baking Water Absorption) . 220 ix Table 35 36 37 38 39 40 41 42 43 44 45 Analyses of Variance- Completely Randomized Design for Mixograph Measurements (At Baking Water Absorption) . . Analyses of Variance- Completely Randomized Design for Mixograph Measurements at 60, 65, and 70% Water Absorption Analyses of Variance- Split Plot Design for Back Extrusion Measurements at Three Shear Rates . . . . . . . . . . . Analyses of Variance- Completely Randomized Design for Bread Contents of Protein, Total Dietary Fiber (TDP), Ash, ‘nd Lipid. O O O O O O O O O O O O O O O O O O O O O O O Analyses of Variance- Complete Block Design for Panelists' Scores of Balady Bread Evaluation . . . . . . . . . . . Analysis of Variance- Balanced Incomplete Block Design for Sensory Combined Scores of Balady Bread . . . . . . . . Analysis of Variance- Complete Block Design of Color measurements of L Values of Bread Top and Bottom Layers and a Values of Bread Bottom Layers . . . . . . . . . . Analysis of Variance- Balanced Incomplete Block Design of Color Measurements of a and b Values of Bread Top Layers and b Values of Bread Bottom Layers . . . . . . . . . . Analysis of Variance- Balanced Incomplete Block Design of Thickness Puncture Force, and Area of Balady Bread Top and Bottm L.Yar a O O O O O O O O O O O O O O O O O O O O O Simple Correlations Between Parinograph and Mixograph Parameters of the Eight Soft Winter Wheat Flour-water Doughs Mixed at the Water Absorption Levels of Baking Balady Bread . . . . . . . . . . . . . . . . . . . . . . Simple Correlation Between Sensory Score Parameters for Egyptian Balady Bread . . . . . . . . . . . . . . . . . Page 221 222 223 224 225 226 227 228 229 230 231 LIST OF FIGURES Figure Page 1 Mill flow for three break, five reduction system for soft wheat on Miag-Multomat mill. (Courtesy of the Soft Wheat Quality Lab., Wooster, OH) . . . . . . . . . . . . . . . . 61 2 Back extrusion curve of the flour-water dough . . . . . . . 67 3 Flour, shorts, and bran milling fractions of the eight soft winter wheat varieties produced by the Miag Multomat mill at the modified settings (data were supplied by Soft Wheat Quality Lab., Wooster, OH) . . . . . . . . . . . . . . . . 87 4 Parinograms (AACC procedure) of the eight soft winter wheat flour-water doughs . . . . . . . . . . . . . . . . . . . . 96 5 Mixograms (AACC procedure) of the eight soft winter wheat flour-Nata! doughS e e s s e s e e e e e e e s e s s e s 10 1 6 Parinograms of the eight soft winter wheat flour- water doughs made at baking water absorption levels . . . . . 108 7 Mixograms of the eight soft winter wheat flour- water doughs made at baking water absorption levels . . . . . 113 8 Mixograms of the eight soft winter wheat flour-water doughs made at 60, 65, and 70% absorption levels . . . . . . . 117 9 Mixogram peak time of the eight soft winter wheat flour-water doughs made at 60, 65, and 70% absorption I'val. O O O O O O O O O O O O O O O O O O O O O O O O O 120 10 Mixogram peak height of the eight soft winter wheat flour-water doughs made at 60, 65, and 70% absorption I'V.1. O O O O O O O O O O O O O O O O O O O O O O O O O 122 11 Mixogram 8-min height of the eight soft winter wheat flour-water doughs made at 60, 65, and 70% absorption lavels O O O O O O O O O O O O O O O O O O O O O O O O O 124 12 Mixogram ll-min area of the eight soft winter wheat flour- water doughs made at 60, 6S, and 70% absorption levels . 127 13 Back-extrusion curves of the eight flour-water doughs prepared at 65\ water absorption and tested at the 9.41 ..c- shear rate O O O O O O O O O O O O O O O O O O O O 129 14 Peak height (load; Newton) of back-extrusion curves of the eight soft winter wheat flour-water doughs at three levels of shear rate . . . . . . . . . . . . . . . . . . . . . 135 15 Curve height at 30 sec after peak as a percentage of peak height of back-extrusion curves of the eight soft winter wheat flour-water doughs at three levels of shear rate . 139 16 Curve area (Newton mm) 30 sec after peak of back-extrusion curves of the eight soft winter wheat flour-water doughs at three levels of shear rate . . . . . . . . . . . . . . 141 xi Figure Page 17 Micrographs of freeze fractured, freeze dried flour-water dough samples made from A, Adena; 8, Auburn; C, Caldwell; D, Charmany flours. Bar- 10 pm. Some of starch granules (Ssintact; SF- fractured) are disclosed from the thick strand- (P8) or web-like (PW) protein network . . . . . 168 18 Micrographs of freeze fractured, freeze dried flour-water doughs made from A, Hillsdale; B, Augusta; C, Frankenmuth; D, Tecumseh flours. Some of starch granules (s-intact; SF- fractured) are disclosed from the thick strand- (PS) or web-like (PW) protein network. Bar- 10 pm . . . . . . 170 19 SEM micrographs of top layers of untreated Balady breads made with A, Tecumseh; B, Hillsdale; C, Frankenmuth flours. Images were collected using the secondary electron detector. (s-starch; P-protein; Es gelatinized starch exudate). Bar- 10 ”m O O O O O O O O O O O O O O O O O O O O O O O O O O O 177 20 SEM micrographs of top layers of Balady bread treated with acetyl ferrocene. Samples were made with Hillsdale (A) and Frankenmuth (B) Flours. Images were collected using the Backscattered electron detector. (Ssstarch; P-protein). Bar- 10 um . . . . . . . . . . . . . . . . . 181 21 SEM micrographs of bottom layers of Balady bread treated with acetyl ferrocene. Samples were made with A, Frankenmuth and B, Adena Flours. Images were collected using the Backscattered electron detector. (s-starch; P-protein). Bar-10 pm . . . . . . . . . . . . . . . . . 184 22 SEM micrograph of areas having highly gelatinized starch in the crumb of untreated Balady breads made with A, Auburn; B, Charmany; C, Caldwell flours. Bar- 10 pm . . . . . 187 23 SEM micrograph of the interior of Balady bread treated with acetyl ferrocene. Samples were made with A and B, Hillsdale; C and D, Adena flours. Images were collected using Secondary (A, C) and Backscattered (B, D) electron emission. (5-starch; P-protein). Bar- 10 pm . . . . . . 189 xii INTRODUCTION Egyptian Balady bread is vitally important not only to the millions of Balady consumers in Egypt, but also to other consumers in the Middle East (Pomeranz 1987). In Egypt and some other African countries, bread alone furnishes more than two-thirds of the total food intake (Pomeranz 1987). Balady bread is the most popular and widely consumed bread among many types of baked bread made in Egypt (Faridi 1988; Pomeranz 1987), constituting 90% of all commercial bread produced (El-Gendy 1983); breads of the Balady-type are also produced and consumed in other Arab countries (Pomeranz 1987). Per capita daily consumption of bread in Egypt ranges from 1.1 to 1.4 kg (Ramadan 1986). Although wheat alone constitutes more than 50% of total cereal grain consumption in Egypt (Pomeranz 1987), national wheat production is limited. During the period 1985-1986, Egyptian. wheat production ‘was 1.9 MT, and consumption ‘was 8.2 MT, requiring a net import of 6.3 MT (Anon 1987), with a forecast of continuous increases in Egyptian wheat consumption and imports. Egypt has been one of the primary markets for 0.8. wheat (Buchanan and Gaylinn 1987). Nevertheless, Mazzarella (1987) reported that during the year 1985-1986, the U.S. supplied Egypt with only 16% of its import of wheat, whereas Austria and Canada; the other two major wheat suppliers of Egypt, provided 68% and 15% of its import of wheat, respectively. In Egypt, Balady bread is produced and distributed on a commercial scale (Edwardson and MacCormac 1984). Commercial bakeries produce nearly all of the bread consumed in the cities and about 20% of that made in the villages (Pomeranz 1987). The Egyptian wheat milling industry provides less than half of the local needs of wheat flours. Buchanan and Gaylinn (1987) reported that the Egyptian wheat flour production, which mainly 2 goes to bread production, averaged 3.5 MT, with slight fluctuations throughout the period of 1978-1985. Ramadan (1986) reported‘daily'national losses of about 7,000 Egyptian pounds (the Egyptian monetary unit) in the bread industry alone as a result of using unsuitable ingredients, mainly flours of inconsistent properties, and because of lack of experience and of unavailability of standardizing apparatus for flour, such as farinograph and mixograph. Legalization and technical reasons have, also, lead to serious additional losses in the Egyptian national economy (Mouse et al 1979; Edwardson and MacCormac 1984). Mousa et al (1979), indicated that the Egyptian Food Administration required the Balady loaf to be sold at constant weight and fixed price. To achieve more profit without legal violation, the bread, more often, is sold ”underbaked' (Edwardson and MacCormac 1984), thereby it weighs more and costs less to make. For the consumer, only the upper crust of such bread is edible and the rest has to be thrown away. Subsidy of wheat and bread by the Egyptian government has, also, contributed to additional currency losses; bread could be used as a cheap source of animal feed (Edwardson and MacCormac 1984). Changing the pricing policy, improving'bread quality, and increasing productivity of the small bakeries were recommended by Edwardson and MacCormac (1984) to reduce bread waste. Pomeranz (1987) and Faridi (1988) described Balady bread and its traditional technique of preparation. Balady bread is a hearth baked, leavened, flat-type bread with a pleasant flavor. The loaf is round in shape (about 25cm in diameter) and has a slightly caramelized outer surface with brown spots. Balady bread is called "Egyptian Pocket bread" because the evolved steam and gas expansion during baking form one large cavity surrounded by a thin layer of crust lined by a small amount of crumb. The dough formula is very simple. Traditionally, wheat flour (of less than 12‘ protein content) of high extraction (82-95%) is used (Edwardson and MacCormac 1984; Morad et al 1984). The percentage of 3 extraction of the flour used is subject to change depending upon the wheat price and the economy of the country (Morad et al 1984). The baker dough formula consists of flour (100%), water (70-85%), table salt (0.5-1.5%), and a fermenting agent (bakers' yeast, or a starter (sour dough) added at 12-17% (Hamed et a1 1973, Mousa et a1 1979, Faridi and Rubenthaler 1983a,b; Morad.«et al 1984). Faridi (1988) indicated that the soft-slack dough is fermented for up to 2 hours, scaled into 120-1709 pieces, flattened (by hand), and baked for a short time (1-1.5 minutes) at high temperatures (500-600°C). Regardless of the large amount of water in dough formula, the moisture content of the baked loaf never exceeds 40% (Refai et al 1962). However, dough rheological characteristics and the organoleptical properties of Balady bread are greatly influenced by the high water absorption levels traditionally used in Balady breadmaking (Mouse et a1 1979; Faridi and Rubenthaler 1983b). Although Balady dough may have up to 85% of water content (Faridi 1988) and this high water content greatly effects bread structure and flavor (Mousa et al 1979), most of the rheological studies made on the wheat flour used in making Balady bread were done at far lower water contents of less than 55-65%. Although the indirect interpretation of dough properties in those studies may be useful, few of those studies have explained the contribution of dough properties to Balady bread quality. Also, Balady bread ultrastructure has not received any attention in contrast to that of pan bread. In order to evaluate suitability of a particular wheat flour in baking some Middle Eastern flat-type breads, Faridi and Rubenthaler (1983b) developed a standardized baking test for each of these types of bread including Balady. This test was used for evaluating the performance of U.S. Pacific Western wheat flours in Balady bread making. Eastern U.S. Soft winter wheat flours did not receive such attention. Faridi and Rubenthaler (1983b) concluded from their study that flour performance was 4 independent of flour protein. They therefore recommended further research to elucidate those factors other than flour protein that control flour performance in Balady bread baking. The current study was conducted in order to: 1. evaluate the suitability of some Eastern soft red and white winter wheats in Balady bread baking, characterize some of the flour quality components and dough properties that control Balady bread quality, develop mathematical models that can be used to predict for baking water absorption and mixing time utilizing available information of flour composition and dough properties, and, study the ultrastructure of flour-water doughs from Eastern wheats at optimum absorption as well as that of Balady breads. REVIEW OF LITERATURE "HEAT FLOUR QUALITY AND COMPOSITION Quality Aspects of Wheat Flour Flour quality has been defined as ”...the ability of the flour to produce a uniformly good end product under conditions agreed to by the supplier and the customer" (Mailhot and Patton 1988). Because of the variability of the baked products made from wheat flours, and the differences in composition and properties among wheat classes, flour quality is associated with the type of end-product (D'Appolonia 1987). According to U.S. standards, wheats are classified into five classes depending on the kernel characteristics (color, texture, shape, and size) and habitat (Yamazaki 1987). These classes are: ‘hard red spring (HRS), hard red winter (HRW), soft red winter (SRW), durum, and white wheats. Flours of HRS and HRW, are called strong or bread flours and are considered of high quality in making yeast-leavened baked products, such as U.S. conventional pan bread (D‘Appolonia 1987). Flours from hard wheats have limited utilization in making confectionery products (Yamazaki 1987) ; durum wheats have their unique utilization in making pasta products (D'Appolonia 1987). Flours from soft wheats are used in the U.S. in making a variety of chemically-leavened confectionery products such as cakes, cookies, wafers, and cones as well as a few yeast-leavened products such as saltines and pretzels (Yamazaki 1987). Yamazaki (1987) stated, also, that flours from soft wheats have particular utilization in overseas countries. Pacific Northwest soft white wheat is imported to the Near and Middle East for making flat breads. Western white wheat is utilized in Japan in making 6 noodles, sweet buns, and other sweet goods. Soft red winter wheat is used in China for making steamed bread and some other confectionery products (Yamazaki 1987). Yamazaki (1987) indicated that baked products such as arabic flat bread, indian chappati and chinese noodles and cakes are more tender when baked from flours of soft wheats. There are two) general approaches to identifying flour quality components: the analytical and the fractionation-reconstitution approaches (MacRitchie 1984). Through the former approach, one correlates the physicochemical measurements made on flours of varying baking potentiality with the quality of the baked products. Measurements that were found in high correlation with baking quality have been used as quick indices for flour quality. Through the second approach, one separates individual components of the flour and recombines them at their same or different proportions to the original flour. The same component can also be exchanged among flours possessing different baking properties. The reconstituted flours are then baked to study the effect of these components on the quality of the final baked product. Each approach has its own advantages and disadvantages. In either approach, one should select the»most important and accurately measured quality criterion of the baked product (MacRitchie 1984). The flour quality criteria which are associated with good baking of U.S. conventional breads were described by Pomeranz (1968) and D'Appolonia (1987). These are high water absorption, suitable mixing requirements, appropriate mixing tolerance, and ability to produce a loaf of large volume and acceptable crumb texture and color. These quality criteria are normally attributed to strong hard wheats of high protein content. D'Appolonia (1987) indicated that the ability of the proteins of flours from hard wheats to form a strong gluten network upon mixing the flour with water makes them unique among flours from other wheat classes in making bread products. 7 Quality of soft wheats appears in the characteristics of baked products produced from‘their flours. Products made from soft wheat flours are relatively less dense and more tender (softer texture), and possess more height or spread than if they were made from flours of hard wheats (Hoseney et al 1988). These quality criteria of soft wheats were attributed by Yamazaki (1987) to their low protein content, low water absorption, and fine granulation of their flours. These characteristics made flours from soft wheats more suitable for making cookies and cakes (Mailhot and Patton 1988). However, because of these characteristics, soft wheat flours are considered weak and, when they are used in making pan bread, produce loaves of small volume with coarse, open crumb structure (Pomeranz 1968). Evaluation of a flour for a particular baked product depends, thereby, on the quality criteria of that product. Tests such as protein content, wet gluten‘content, sedimentation'value, dough fermentation time, amylase activity, and damaged starch content are used for quick assessment of the quality of flours from hard wheats (Pomeranz 1968; D'Appolonia 1987). On the other hand, measurements such as moisture, protein, damaged starch, and ash content, as well as flour milling yield, particle size index, viscosity and Alkaline water retention capacity (AWRC) are among the routine tests used for evaluation of soft wheat flours (Yamazaki 1987; Hoseney et a1 1988). Pyler (1988) described some of the tests that are in use for evaluation of flour quality and gluten strength. Among these tests are the sedimentation (or Zeleny) test and wheat meal fermentation time (or Pelshenke) test. Flours of low protein content and poor baking quality will show sedimentation values lower than or equal to 20mL, whereas, high-protein flours of superior baking quality will show values equal to or grater than 55mL (Pyler 1988). The Zeleny test provides an estimate for gluten strength and it takes values from 3mL to more than 70mL (Halverson and Zeleny 1988). A sedimentation value of 14.8 mL was reported by Sarhan et a1 (1986) for a commercial Egyptian wheat flour of 72% extraction. ’Flour of poor gluten quality will show values equal to or lower than 40 minutes in the fermentation time test, whereas, flours of potential gluten quality will register values equal to or greater than 90 minutes (Pyler 1988). The test provides an estimate for baking strength of wheat meal and it takes values in a range wider than 30-400 minutes (Halverson and Zeleny 1988). The fermentation time test (FTT) was used by Abu El-Azm (1989) to» evaluate two flours of 82% and 73% extraction obtained from the Egyptian wheat variety Giza 157. The 82% extraction flour had FTT of 250 min, while the 73% extraction flour had FTT of 350 minutes. The alkaline water retention capacity (AWRC) measures the capacity of wheat flour to absorb and retain water under alkaline conditions and has been *used to predict flour quality in baking cookies (Yamazaki 1987). Cookie quality as measured by spread was found to be in a strong negative correlation with flour absorption as measured by AWRC. Abboud et al (1985) analyzed 44 wheat flours representing the four'wheat classes. .AWRC of these samples was found to be in the range 53.8 - 67.8% (14% m.b.). Their data indicated that the 11 soft white winter flours included in the study had AWRC in the range 54.0-60.6% (14% m.b.). Protein content is measured as total nitrogen by using the Kjeldahl or the standardized Near Infrared Reflectance methods. It varies among and within the wheat classes. Protein contents in the range of 11-18%, 10-15%, 8-12%, 7-10%, 11-16% were reported for HRS, HRW, SRW, white and durum wheat classes (D'Appolonia 1987). Protein quality may be evaluated by measuring the amount of wet gluten extracted from the flour-water dough by kneading under continuous stream of water. Abu El-Azm (1989) milled Giza 157, a soft wheat variety grown in Egypt into two flours of 82% and 73% extraction. The author found that the wet and dry gluten of the 82% extraction flour had the values of 33.78 and 17.09%, respectively. The comparable values for the 9 73% extraction flour were 32.44 and 16.40%, respectively. Sarhan et al (1986) reported that wet and dry gluten of a commercial Egyptian wheat flour of 72% extraction were 26.09 and 9.38%, respectively. Cooke (1986) found that crude gluten extracted from the soft wheat flour of Augusta, Hillsdale, Frankenmuth, and Tecumseh were 12.30, 12.50, 13.45, and 15.48g/100g (d.b.) flour, respectively. The amylase activity test conducted using the a viscometer or a calorimeter measures flour a-amylase activity. High activity may result from heat, field sprout, or frost damage. High a-amylase activity adversely affects dough properties and baking quality of the flour (D'Appolonia 1987). Finney et al (1980b) baked Balady bread from flours milled from sound and field-sprouted soft white wheats. As the degree of sprouting increased, Balady dough became sticky and difficult to handle. That difficulty was avoided by decreasing time of mixing and amount of water absorption. ,Dusting the dough*with flour'was required, particularly at the early stages of dough molding, and was not necessary thereafter. Flours of different levels of field-sprout produced loaves of equal acceptability in terms of layer separation, crust to crumb ratio, color, taste, and shape. Faridi (1988) indicated, also, that flat breeds are more tolerant to variation in ingredients and conditions of preparation. The damaged starch test measures the extent of mechanical damage to the starch granules of the flour introduced by milling process. Ford and Ringswood (1981) found that increasing the feed rate during milling increased the amounts of flour released and of damaged starch. They recommended an increase in the role speed of the>mill to reduce the amount of damaged starch when milling at a high feed rate. Moderate starch damage is required for bread flour as it increases flour absorption and provides more fermentable sugars for the yeast, both of which contribute to bread quality. However, excessive starch damage will produce sticky dough and an inferior quality bread (D'Appolonia 1987). Finney et a1 (1988) showed that enzymatically measured damaged starch content of flour 10 milled from soft wheats was in a narrow range of 2.6-4.3%. Flours from hard wheats showed extended but higher ranges. These physicochemical tests are complimentary to the baking test for each particular baked product (Hoseney et a1 1988). Hoseney et al (1988) indicated that differences among soft wheats (white, red, or club) would not be detected from such tests as kernel hardness or milling properties but rather from baking tests. For this reason the baking test is considered the ultimate test for flour quality. Standardized tests for baking sugar cookies and high ratio cakes are used for evaluation of soft wheat flours (Yamazaki 1987; Hoseney et al 1988). Baking tests for evaluation of soft wheat flours in making different international breads (including Balady bread) were used by Finney et al (1980b), and Faridi and Rubenthaler (1983b). There are two standard baking tests for evaluation of bread flours in making U.S. pan bread (AACC 1983). These tests are intended to measure protein quality (Pomeranz 1987). Loaf volume of U.S. conventional pan bread, cookie diameter or the spread ratio, and cake height has been used as the quality criteria for these baked products (Pomeranz 1987; Yamazaki 1987). Protein content of strong flours is associated with pan bread loaf volume, whereas AWRC of cookie flour correlates well with cookie spread. Protein content has been used as a single index for quality of pan bread, whereas, AWRC has been used as an index for cookie quality (Mailhot and Patton 1988). Balady bread quality has not been judged by just a single characteristic; rather, pocket formation, layer separation, and bread shape and color can be used as the evaluation criteria for Balady quality (Morad et al 1984). Mouse et al (1979) indicated that bread consumers in Egypt prefer Balady loaves of large volume and consider this characteristic as the most important in bread acceptability. The Egyptian Food.Administration demands, however, a fixed loaf weight; therefore, loaf specific volume was recommended by Mouse et al (1979), as the quality criterion in evaluating Balady bread. 11 The loaf volume of Balady bread is associated with the degree of puffing and pocket formation during bread baking. Puffing and separation of the loaf into two layers were among the evaluation criteria for Balady bread used by Finney et al (1980a), Faridi and Rubenthaler (1983b), and Morad et al (1984). Other characteristics used by these authors for evaluation of the Balady bread were thickness of upper and bottom layers, crust color, crumb softness, and taste. Refai et a1 (1962) described the criteria of two commercial wheat varieties: Baladi and Hindi, traditionally used for Balady bread making in Egypt. These varieties had low protein content (7.1 and 8.1%; 14% m.b.), weak gluten strength, and medium water retention capacity. These quality attributes were assessed by Refai et al (1962), using Rjeldahl, sedimentation (11.0 and 13.8 Ml), fermentation-time (17 and 26 minutes), farinograph and alveograph tests. Hamed et al (1973) recommended flours having an alveograph proportional number greater than 0.7 for Balady bread making. However, the alveograph test utilizes a dough sample prepared at a fixed water absorption of 51.4% (Bloksma and Bushuk 1988) which is far lower than that commonly used for balady bread production (Faridi 1988). Flour Composition Composition of wheat flour depends on several factors, such as varietal differences, climatic and growing conditions, milling procedures, extraction rate, and storage conditions. Pomeranz (1980a,b) indicated that flour protein content, for example, is both an environmental and an heritable trait; while protein quality is heritable only. Different varieties have proteins of differing quality potential. Within a variety, a positive linear relationship exists between protein content and bread loaf volume. Flour protein quality can be expressed in the number of units of loaf volume per one unit protein content (Pomeranz 1980a,b). Climatic conditions greatly affect dough properties and the baking quality of the flour; drought during growing, as well as excessive rain at 12 time of harvest, have'a.deteriorative effect on flour quality (MacRitchie 1984). An increase in alpha-amylase and proteolytic enzyme activities in flour results from rain damage. Dough that is produced from such flour is relatively weak and sticky. Shortage of soil sulfur affects protein quality, while limited nitrogen*will decrease the’protein content (Moss et al 1981). Bushuk (1985) indicated also that the protein content of wheat varies according to the growing conditions. Soil moisture and nitrogen content, as well as temperature, are among those environmental factors. Yamazaki (1987) mentioned that the growing conditions of soft wheat favor high yield and low protein content. The milling process also affects the composition and quality of the flour. Normally, soft wheats have a flour yield in the range of 72-79% (Yamazaki and Andrews 1982). In Egypt, wheat is milled to yield flour of 82-95 % extraction for the making of Balady bread (Morad et a1 1984). Finney et al (1980b) studied theteffect of flour level of field sprouting, and variation of ingredients and breadmaking conditions on Balady bread quality. Finney et al (1980b) milled sound and field-sprouted Pacific Northwest soft white wheat composites using a Buhler mill. Three fractions (flour, shorts, and bran) were obtained. Flour yield from tempered wheats ranged from 71 to 74%; whereas, that from dry milling ranged from 81 to 84%. To achieve a higher extraction rate (85, 90, 95, or 100%), shorts and bran fractions were combined, reduced in particle size by repetitive grinding and sifting, and then added, as needed, to the flour fraction. MacRitchie (1984) reported that excessive grinding deteriorates flour quality, and flour properties may be controlled by varying the grinding intensity. Abu El-Azm (1989) found that protein, fat, crude fibers, and ash contents of flours milled from the same wheat variety increased, whereas total carbohydrate content decreased as the flour extraction rate increased. MacRitchie (1984) reported also that high temperature and moisture content, as well as long duration of wheat storage, are detrimental to flour quality. 13 Flour Proteins: The protein content of wheat kernels showed a wide range of 8.3-19.3% (d.b.) and an average of 13.8 % (Davis et al 1981). Davis et a1 (1981) analyzed five market wheat classes and four subclasses of white wheats grown for 3 years at different locations and found that the protein content of wheat varied significantly (P<0.05) by year, wheat class, and growing location. Davis et al (1981) found that soft.white'winter wheats, in comparison with soft red winter wheats, had significantly lower protein content. They reported an average protein content of 11.54 % for soft white winter wheats and 12.78 % for soft red winter wheats. Loving and Brenneis (1981) indicated, also, that straight grade flours of soft white wheats had generally lower protein content than those of soft red wheats. Zabik and Tipton (1989) reported that protein contents (d.b.) of straight grade flours from Augusta, Frankenmuth, and Tecumseh (three soft white winter wheat varieties) were 8.01, 9.01, and 10.83%; respectively, whereas that of Hillsdale, a soft red winter variety, was 8.08%. Abu El-Azm (1989) reported protein content of 11.72, 10.34, and 9.70% (d.b.) for 100, 82, and 73% extraction flours milled from the Egyptian soft wheat variety Giza 157. A commercial Egyptian wheat flour of 72% extraction and 12.93% water content was reported by Sarhan et a1 (1986), to have 11.8% (m.b.) protein content. Wheat flour proteins can be separated either by direct solvent extraction from the flour (Osborne 1908) or after a dough making step ”gluten wash technique” (Hoseney et al l969a,b; MacRitchie 1978). Wheat flour proteins can be classified according to their solubility into water soluble (albumins), saline soluble (globulins), 70%-alcohol soluble (prolamins), and acid or alkaline soluble proteins (glutelins) (Osborne 1908). Pomeranz (1980a,b) indicated that proteins of wheat flour can be classified .into dough forming proteins, namely gluten, and non-dough forming proteins or non-gluten proteins. Gluten proteins which comprise 14 85% of total flour proteins and are responsible for dough formation, can be further separated into a low molecular weight fraction, gliadin (25,000 - 100,000), and a high molecular weight fraction, glutenin (>100,000). The glutenin proteins are characterized by their elasticity and low extensibility. They are able to form complexes with lipids. On the other hand, the gliadin proteins are more extensible and less elastic. The other non-gluten fraction (15% of total flour proteins) can be fractionated into albumins and globulins proteins as well as free peptides and amino acids. Recent progress in protein extraction, fractionation, and identification techniques such as open column chromatography, gel electrophoresis, and high performance liquid chromato-graphy had been reviewed by Bietz (1986) and Wrigley and Bietz (1988). Wrigley and Bietz (1988) stated that the classical nomenclature of wheat proteins, although widely accepted, is inadequate. They recommended that wheat protein nomenclature be related to the method of fractionation, functional properties, genetics, and site of synthesis or storage location in the cell. Many fractionation-reconstitution approaches have been applied to identify flour components responsible for dough properties and baking quality. Some techniques (MacRitchie 1978) start by defatting the flour using the proper solvent. Others skip the lipid removal step. Generally, reconstitution techniques can be divided into two main groups. The first group (Chen and Bushuk 1970) follow a procedure similar to Osborne's procedure (Osborne 1908) , in which albumins and globulins are separated by dissolving them into 0.5 M NaCl, then dissolving the gliadins in 70% aqueous ethanol. Finally, the acid soluble glutenin is dissolved in a dilute acid (acetic or lactic) leaving the acid insoluble glutenin fraction and the starch as a residue. The second group of techniques (Hoseney et al 1969a,b; MacRitchie 1978) separate the gluten fraction after hand- or mechanical-kneading and 15 washing out the starch and the water solubles. Starch is then separated by centrifugation leaving the supernatant which contains albumins, globulins, and other water soluble constituents. The gluten fraction is further separated into its two sub-fractions, gliadin and glutenin, by dissolving the gliadin with a dilute acid leaving the larger molecular weight glutenin as a residue. ‘ After the fractionation step comes the reconstitution step. Success of both steps can be judged by the baking performance of a reconstituted flour, of which the fractions are added together at their original levels in the starting flour. If both flours performed equally, the properties of the separated fractions have not been altered by the extraction and reconstitution procedure and further studies on these fractions will be meaningful. Bushuk and co-workers (Orth and Bushuk 1972; Orth et a1 1972) used a modified Osborne procedure (Osborne 1908). They found that the level of insoluble glutenin proteins effects loaf volume and correlates well with dough strength. Shogren et al (1969) fractionated wet gluten by dissolving it in lactic acid (0.005 N), then ‘precipitated into several fractions at different Ph levels (4.7, 5.6, 5.8, and 6.1 insoluble, and 6.1 soluble fractions) using 0.1 N sodium carbonate. They found that as the pH increased for a particular fraction the gliadin increased while the glutenin decreased. This was accompanied by a large decrease in mixing time, baking absorption, and loaf volume. Hoseney et al (1969b) slightly modified the fractionation procedure of Shogren et al (1969). They dissolved gluten in 0.005 N lactic acid and separated it into three fractions depending on the centrifugational force: the insoluble fraction at 1,000 X g, the soluble fraction at 1,000 X g ”glutenin", and the soluble fraction at 100,000 X g ”gliadin-rich”. They found that the ”insoluble fraction” had no effect in bread baking, the 16 glutenin fraction was found to control mixing requirements, and the "gliadin-rich" fraction effected loaf volume. MacRitchie (1978) dissolved gluten in 0.1 M acetic acid. After centrifugation the supernatant (60%) was denoted ”gliadin", whereas the residual or pellet (40%) was denoted ”glutenin”. The author concluded from a baking study that the low molecular weight fraction, gliadin, decreased dough strength and mixing stability. The high molecular weight insoluble fraction, glutenin, increased farinograph developing time, the extensigraph height and area, and reduced farinograph dough breakdown time. Gluten proteins were fractionated by Preston and Tipples (1980) using diluted acetic acid. They obtained only two fractions: acid soluble and acid insoluble. The acid soluble fraction was found to control dough strength and to increase loaf volume, whereas the acid insoluble fraction was found to reduce loaf volume. Some conflict was found among published reports regarding which of the protein fractions the dough properties and breadmaking quality are attributed. That contradiction is related to structural differences in the fractions themselves as a result of differences in the fractionation techniques (Chakraborty and Khan 1988a). Chakraborty and Khan (1988a,b) applied the three methods of Hoseney, Bushuk, and MacRitchie in the separation of protein fractions from two hard red spring wheats of varying breadmaking quality (BMQ) . They reported that exchanging the water soluble fraction (WSF) of the three methods between the two wheat varieties produced a different effect on loaf volume depending on the fractionation procedure. Chakraborty and Khan (1988b) also found that separated gliadin and glutenin fractions from flours 'of poor and good BMQ when exchanged, produced different effects according to the separation procedure. It was concluded from their study that the glutenin-rich fraction of the gluten controls loaf volume. This conclusion agrees with that of MacRitchie 17 (1985), but was in disagreement with that found by Hoseney et al (l969b), who indicated that the gliadin, not the glutenin, is the fraction that controls loaf volume. Clements (1987) studied the electrophoretic difference among soft wheat varieties from the Eastern U.S. with respect to gliadin fractionation pattern. After extracting gliadins using ethylene glycol, Clements (1987) used 10% acrylamide slab'gel to separate gliadin fractions from'soft white and red wheat cultivars. The main differences found among cultivars were related to the configuration of bands in the middle region of the electrophoretic patterns. Based on that configuration, soft wheats could be categorized into four types. Type I had one single heavy band, type II had two closely spaced heavy bands. Type III had two widely spaced bands of moderate to heavy intensity, and type IV had three or more bands of moderate intensity. Clements (1987) found that most soft wheats to be of type III, according to the electrophoretic pattern of their gliadins. According to the electrophoretic pattern of their gliadins, Adena and Charmany, two soft red winter cultivars were of type I which possessed one heavy band. Augusta and Tecumseh, two soft white types, and Auburn, a soft red wheat cultivars were of type II, which possessed two closely spaced heavy bands. Frankenmuth and Hillsdale, a.white and red soft winter wheat cultivar were of type III, whereas Caldwell, a red soft winter cultivar was of type IV. Abu El-Azm (1989) fractionated proteins of two Egyptian flours of 82% and 73% extraction into water, alcohol, salt, and alkali soluble fractions. The values of these fractions in the 82% extraction flour were 8.75, 15.5, 4.32, and 50.5%, respectively, whereas those of the 73% extraction flour were 9.3, 16.5, 6.7, and 49.3%, respectively. This data indicates that as the extraction rate of the flour increased, the amount of the alkali-soluble protein fraction increased, while the other protein fractions decreased. It should be noted that the author used 50% aqueous ethanol for separation of the alcohol soluble fraction. 18 Zabik and Tipton (1989) used the gluten wash technique for fractionation of flours (72.5-75.5% extraction) from four soft wheat varieties to study the effects of fractionation and reconstitution of the flour on the quality of pie crust. The gluten extract from each flour was further fractionated into four sub-fractions depending on their solubility at different pH levels. These sub-fractions were pH 4.7, 5.6, 5.8/6.1 insoluble and 6.1 soluble proteins. The insoluble gluten sub- fractions at lower pH possessed glutenin-like characteristics, whereas the insoluble gluten sub-fractions at higher pH possessed gliadin-like characteristics. These authors reported that Augusta flour showed a fractionation pattern of its gluten that was opposite to that of Hillsdale, whereas Frankenmuth and Tecumseh showed similar patterns that were in between those of Augusta and Hillsdale. Their results suggested that the gluten of Hillsdale, in contrast to that of Augusta, was relatively rich in gliadin and poor in glutenin, whereas those of Frankenmuth and Tecumseh had intermediate amounts of both gluten sub- fractions. Gliadin proteins have been known to contribute fluidity and extensibility to the gluten, whereas glutenin proteins contribute to its strength and elasticity (Pomeranz 1987). Therefore, it is expected from the report of Zabik and Tipton (1989) that the dough of Hillsdale would be weaker and more extensible than those of Frankenmuth and Tecumseh, whereas that of Augusta would be stronger and more elastic. Two of the most important groups that play a great role in protein structure and which affect dough properties are the thiol (SH) and the disulfide (SS) groups. The SS groups have a stabilizing effect on the structure of the dough, particularly on the gluten complex (Jones et a1 1974). Such effect exists at three levels: within protein molecules, between multimolecular aggregates of protein, and between the large aggregates of protein. 19 The thiol groups in.a dough system are distributed at three different locations. They can be found buried in the interior of protein molecules, on the interior surfaces within multimolecular aggregates of protein, or at the outer surfaces of protein aggregates. Jones et a1 (1974) estimated the total and the rheologically important SH and SS groups in the dough system. They also indicated that the SH and SS containing compounds of small molecular weight, especially glutathione and oxidized glutathione, mediate the SH/SS exchange reactions that take place among the SH and SS groups of large molecules in the dough. Mailhot and Patton (1988) indicated that gluten proteins possess elasticity and extensibility, the two properties essential for breadmaking. Glutenins contribute to mixing time, strength, and elasticity, whereas gliadins contribute to extensibility and stickiness. Flour Carbohydrates: Total carbohydrate content (calculated by difference) of a wheat kernel ranges from 65.4 to 78.9 (%, d.b.) with an average of 72.4 (Davis et al 1981). Davis et al (1981) analyzed five market wheat classes and flour subclasses of white wheats grown for 3 years at different locations. Differences in carbohydrates varied significantly only by class. -Davis et al (1981) found that soft white'winter wheats, in comparison with soft red winter wheats, had significantly higher carbohydrates content. They reported an average total carbohydrate content of 74.63 % for soft white winter wheats and 72.20 % for soft red winter wheats. Abu El-Azm (1989) reported a total carbohydrate content of 81.0, 84.6, and 86.6% (d.b.) for 100, 82, and 73% extraction flours milled from the Egyptian soft wheat variety Giza 157. A commercial Egyptian wheat flour of 72% extraction was reported by Sarhan et al (1986) to have 72.8% (m.b.) total carbohydrate content. Lineback and Reaper (1988) indicated that carbohydrates compose 80% (on dry basis) of wheat kernels. They can be classified according to 20 their polymeric structure into mono-, oligo- and polysaccharides. The monomeric unit of carbohydrates can be further classified, according to their chemical structure, into pentoses which are polyhydroxy aldehydes of five carbon atom molecules, e.g. D-xyloee and L-arabinose, and hexoses of six carbon atom molecules such as polyhydroxy aldehydes, e.g. D-glucose and D-galactose, or polyhydroxy ketones, e.g. D-fructose. Another group of monomeric units are hexuronic acids, e.g. glucuronic acids. According to Lineback and Rasper (1988) the oligo-saccharides are linear polymers of less than 10-12 monomer units, e.g. sucrose, raffinose, maltose, and glucofructans. Polysaccharides are higher molecular weight polymers that may be composed of one type of monomers and thereby, are called homopolysaccharides, such as starch and cellulose or of several monomers and thereby are called heteropoly-saccharides, such as hemicelluloses and pectins; they may possess a linear or a branched structure. Polysaccharides can also be classified, according to their function in the plant, into structural polysaccharides which make‘or support the plant cell walls, e.g. cellulose, hemicellulose, and pectins, and storage polysaccharides which are energy reservoirs in the paant, e.g. starch (Lineback and Rasper 1988). The structural polysaccharides, contrary to the storage polysaccharides, are not digestible by human enzymes, and thereby belong to the so called dietary fiber group. Lineback and Rasper (1988) stated that starch is the major carbohydrate component (63-72%) of wheat grain. The average starch content in soft wheats is 69%, whereas that of hard wheats is 64%. They added that a reverse relationship exists between protein content and starch content of wheat. Cells of wheat endosperm contain starch as granules of complete integrity. The starch granule is a mixture of two high molecular weight polysaccharides, amylose and amylopectin. Amylase, conventionally considered as a linear polymer, is built of glucopyranose monomers attached by alpha-D(l-4) glycosidic linkages. 21 Amylopectin is a highly branched polymer. Its build-up is similar to that of the amylase, in addition to alpha-D(l-6) glycosidic linkage at the branch points which exist at every 20-25 glycopyranose residues. The two starch fractions are highly associated in the granule through hydrogen bonding. Wheat starch contains minor constituents of non-carbohydrate classes such as lipids, proteins, and phosphorus (Lineback and Rasper 1988). Phosphorus is present in the form of phospholipids. Starch protein can be easily extracted from starch by SDS solution and might be associated with the granule surface (Greenwell and Schafield 1986). The authors showed by electrophoresis that starch proteins contained a fraction of 15,000 molecular weight. The amount of such fraction was much higher in soft wheats than in hard wheats, and was absent in durum‘wheats. Therefore, it has been related by the authors to endosperm softness. Abboud et al (1985) analyzed 44 wheat flours representing the four wheat classes; damaged starch in these samples was found to be in the range 2.50 - 7.65% (14% m.b.). They stated that the amount of damaged starch in the flour reflected, among other factors, wheat kernel hardness and severity of milling. Flours from club wheats had the smallest content of damaged starch followed by those from soft white spring and soft white winter, whereas those from hard red wheats had the highest average of damaged starch. Their data indicated that the 11 soft white winter flours included in the study had. damaged starch content in the range of 3.07-5.08% (14% m.b.). Hoseney (1986) reported that starch in its aqueous suspensions absorbs water up to one-third of its weight and swells up to 5% of its volume. Starch-water uptake and swelling are greater for damaged starch and partially damaged starch granules than for intact ones (Pomeranz 1968). MacRitchie (1984) indicated that damaged starch, produced during milling, affects water absorption capacity of the flour. 22 It also has some influence on dough properties, production of fermentable sugars, loaf volume and crumb texture (Pomeranz 1968). Abu El-Azm (1989) found that water retention capacity increased as the flour rate of extraction was increased. Yamazaki (1953) indicated that the flour water retention capacity (WRC) measured under either acidic or alkaline conditions has been successfully used for predicting bread dough absorption and cookie spread, respectively. The author indicated that flour imbibes water at any pH level, but gluten hydration is limited at moderately alkaline pHs. Alkaline WRC does not require adjustment for flour protein or ash contents when used for predicting cookie quality, whereas acidic WRC needs such adjustment when predicting for breadmaking quality. Pentosans, a type of complex carbohydrate of the hemicellulose group, are polymers of xylose plus variable amounts of other pentoses and hexoses (Wisker et a1 1985). They are constituents of wheat dietary fibers and have great capacity to absorb and retain water as a results of their unique structure. Bushuk (1966) studied the distribution of water in the dough and indicated that pentosans, although constituting a small percentage of the flour, have the greatest capacity to absorb‘water up to 23% of total water (TW) in the dough. Also, 31% of TW is expected to associate with the gluten, whereas up to 45.5% of TW associates with the starch. That amount associated with the starch is greatly reduced as the flour content of damaged starch is minimized. Abu El-Azm (1989) reported crude fiber content of 2.04, 1.14, and 0.81% (d.b.) for 100, 82, and 73% extraction flours milled from the Egyptian soft wheat variety Giza 157. A commercial Egyptian wheat flour of 72% extraction was reported by Sarhan et al (1986), to have 0.35% (m.b.) crude fiber content. Asp et al (1983) found whole wheat flour to contain TDF of 10.3%, whereas wheat flour of regular extraction had 2.4%. Higher values of TDF 23 were reported by Prosky et al (1985) for whole wheat flour (12.57%) and white wheat flour (2.76%). Abboud et al (1985) analyzed 44 wheat flours representing the four wheat classes. Total pentosan content of these samples was found to be in the range 1.67 - 2.58% (14% m.b.). Their data indicated that the 11 soft white winter flours included in the study had pentosan content in the range of 1.92-2.58% (14% m.b.). Flour Lipids: Total lipids in whole wheat grain ranges 2-4% (Morrison 1978); however, lipid content of regular wheat flour is about 2% (Chung et al 1980). Of the total flour lipids, 25% is located within the starch granules (MacRitchie 1984). The non-starch lipids can be classified according to their solubility. Morrison (1983) indicated that germ and aleurone layers contain equal amounts of lipids, mostly triglyceride, sterylesters, and diacyl phaspholipids. According to Pomeranz and Chung (1978), wheat flour lipids can be differentiated into two categories; the free- and bound-lipids. Non-polar solvents such as ether or petroleum‘ether can be used to extract the flour free lipids. The other category, bound lipids, can be further extracted from such flour using a polar solvent such as water-saturated butanol or a mixture of chloroform-methanol-water. Both the free- and bound- lipids can be further fractionated into nan-polar and polar fractions. The free lipids in flour contain 70% non-polar lipids and 30% polar lipids. On the other hand, the flour bound lipids contain 30% non-polar lipids and 70% polar lipids. The polar-lipid fraction of the free lipids is comprised of one-third phospholipids and two-third glycolipids. The last two lipid classes are found in equal amounts in the polar fraction of the flour bound lipids, but the net amounts of both are greater than that found in the free lipid category. Phospholipid fractions of the flour free lipids are mainly phosphatidyl choline while those of the flour bound lipids are in mainly lysophosphatidyl choline. 24 Interaction of wheat flour lipids with proteins during protein separation or dough formation was reviewed by Chung (1986) . The author indicated that several lipid fractions (particularly the glycolipids) from the petroleum ether extract and their ratios are associated with differences among wheat varieties with respect to mixing time and baking quality. MacRitchie (1984) summarized the effects of lipids and lipid fractions on pan bread quality. When added back to petroleum ether extracted flour, nonpolar lipids are detrimental to breadmaking quality, while polar lipids are an effective improver of such quality. Of the nonpolar lipids, free fatty acids added to defatted or original flour resulted in a decrease in loaf volume. Improving petroleum ether defatted flour by adding polar lipids depends on their type and quantity. Returning polar lipids back to defatted flours was deleterious when smaller amounts were used but beneficial when larger amounts were added. Glycolipids from the flour free lipid fraction had an improving effect when added to petroleum ether defatted flour. Phospholipids, on the other hand, had a slightly deleterious effect. Di-galactosyl-di-glycerides were a more effective addition to the petroleum ether defatted flour, especially when 3% shortening was added. Adding shortening to the baking formula of pan bread facilitates dough manipulation and improves loaf volume, crumb grain, consumer acceptability and shelf-life characteristics. The total lipid content of wheat kernels ranges from 1.51 to 3.37 (%, d.b.) with an average of 2.30 (Davis et al 1980, 1981). Davis et al (1980, 1981) analyzed five market wheat classes and flour subclasses of white wheats grown for 3 years at different locations; differences in lipid content varied significantly by year and class. Davis et al (1981, 1980) found that soft white winter wheats, in comparison with soft red winter wheats, had significantly lower total lipid contents. Lipid content averaged 2.22 % for soft white winter 25 wheats and 2.57 % for soft red winter wheats. Abu El-Azm (1989) reported fat content of 1.69, 1.15, and 0.71% (d.b.) for 100, 82, and 73% extraction flours from the Egyptian soft wheat Giza 157. Flour Ash: Bass (1988) indicated that ash content cannot be used as a quality index when wheat flours from different classes are compared because of the variation in ash content of their endosperms. The author also stated that ash is more concentrated in the kernel fractions bran, aleurone, and germ than in the endosperm. Moreover, the amount of ash in the endosperm decreased towards the kernel center. Mailhot and Patton (1988) stated that ash content of flour correlates with components of wheat kernel that influence color. They added that ash content of a flour is not related to its performance and baking quality but rather to the degree of flour refinement during milling. The higher the flour ash content, the darker is the baked product as it contains fine bran particles of more of the endosperm portions adjacent to the bran. Ash content of the flour is probably a genetic and/or environmental attribute. Ash content of wheat kernels ranges from 1.17 to 2.96% (d.b.) with an average of 1.74% (Davis et a1 1981). Davis et al (1981) analyzed five market wheat classes and flour subclasses of white wheats grown for 3 years at different locations. Ash content of wheat varied significantly (P<0.05) by year, wheat class, and growing location. Davis et al (1981) found that soft white winter wheats, in comparison with soft red winter wheats, had significantly lower ash content. They reported an average ash content of 1.69 % for soft white winter wheats and 2.00 % for soft red winter wheats. Cooke (1986) reported that the whole meal ash contents (14% m.b.) of Augusta, Frankenmuth, and Tecumseh, three soft white winter wheat varieties, were 1.53, 1.68, and 1.72%, respectively, whereas that of Hillsdale, a soft red winter wheat variety, was 1.57%. 26 Abu El-Azm (1989) reported ash content of 1.30, 0.95, and 0.60% (d.b.) for 100, 82, and 73% extraction flours milled from the Egyptian soft wheat variety Giza 157. A commercial Egyptian wheat flour of 72% extraction was reported by Sarhan et al (1986), to have 0.69% (m.b.) ash content s Vita-ins Content: Davis et al (1981) analyzed five market wheat classes and flour subclasses of white wheats grown for three years at different locations. They stated that wheat is a valuable source of water soluble vitamins. Thiamin, riboflavin, niacin, and pyridoxine content of wheat kernels had the range of 0.33-0.65, 0.10-0.17, 3.8-9.3, 0.16-0.79 (mg/1009 wheat, d.b.) with an average of 0.46, 0.13, 5.5, and 0.46 (mg/1009 wheat, d.b.). The soft white winter wheats, in comparison with soft red winter wheats, were lower in thiamin, and riboflavin, but higher in pyridoxine contents. Both wheat groups had similar amounts of niacin. 'Tabekhia and Mohamed (1971) measured the thiamin (TH), riboflavin (RF), and nicotinic acid (NA) contents of some Egyptian foods. Their study of the effect of flour extraction of the Egyptian wheat variety Hindy Tauson indicated that the levels of these three vitamins increased as flour extraction was increased. The flour of 89.5% extraction contained TH, RF, and NA in the amounts of 243, 46, and 2119 ug/100 g flour (d.b.), respectively. The respective values for the whole wheat flour were 552, 122, and 4921 ug/lOOg, whereas those for the 72% extraction flour were 86, 25, and 1514 ug/100g, respectively. The 87.5% extraction flour used in their Balady bread baking had 443 ug/lOOg of TH, 114 ug/lOOg of RF, and 1296 ug/100 g of NA. By the end of the dough fermentation process, these values were found to increase by 7-14%. Baking at 35090 for 1.5 min resulted in a reduction in TH, RF, and NA by 25%, 26%, and 2.5%, respectively from their original values of the flour. 27 Mineral Content: Davis et al (1984) analyzed five market wheat classes, with_ four white wheat subclasses, for their mineral content. The mean amount of Ca, Mg, P, and K were 40, 133, 516, and 454mg/100g (d.b.) of wheats over 3 crop years and 49 growing locations. Also, they reported that Cu, Fe, Mn, and Zn content of wheat had the mean value of 0.49, 7.9, 4.4, 4.7 mg/lOOg (d.b.). In their comparison of mineral contents among wheat classes and subclasses, HRS had more Mg and Zn, HRW had more Ca, SRW had more P, and SWS had more R and Cu. Only iron showed no significant difference between classes. Flour of high extraction contains high amounts of fiber and phytate, which have been known to interfere with bioavailability of minerals such as zinc, magnesium, calcium, and iron (Faridi et a1 1983). They showed that phytic acid was reduced up to 82% in sour dough or yeast (1-2%) fermented dough after 3 hours of fermentation. Phytate destruction was decreased as flour extraction was increased- Fermentation time, dough pH, and flour extraction controlled the extent of the phytate destruction. Dough pH is mainly a function of fermentation time, temperature, and the leavening agent. Dough Rheological Characteristics and Measurements Hoseney et a1 (1988) listed the instruments that have been conventionally used for evaluation of soft wheat quality. These included the farinograph, mixograph, alveograph, and. Mac* Michael viscometer. However, these instruments provide information that is complementary to any specific baking test designed to evaluate flour quality in producing a particular baked product (Hoseney et a1 1988). Halverson and Zeleny (1988) indicated also that hard wheat quality can be described in terms of the farinograph, mixograph, amylograph, and breadbaking data. 28 Menj ivar (1990) classified rheological measurements into fundamental, empirical, and imitative. The fundamental methods provide well-defined physical properties of the tested material and help in studying the relationship between its properties and structure particularly in the area of process engineering. The empirical methods provide useful parameters about dough properties and are usually inexpensive, fast, and sturdy; however, their parameters are not well defined. In the imitative’methods, physical properties of the material are measured under conditions that simulate actual applications. They also provide empirical parameters and require some experience. According to Menjivar (1990) the extensigraph, brookfield viscometer, and back.extrusion tests are considered empirical, whereas the farinograph and alveograph are examples for imitative tests. Fundamental properties, on the other hand, can be attained from the measurements of parallel plate, cane-and-plate, and tube viscometers. Bloksma and Bushuk (1988) provided an excellent review of dough rheology. The Farinograph Test The farinograph is a recording dough mixer by which the dough is mixed at a constant speed (Pomeranz 1987). The trace produced is called the farinogram which represents the power required for mixing the dough against the time. Dough properties that can be measured using the farinograph are water absorption (FA), mixing (development) time, mixing tolerance index (MTI), stability, breakdown time, and valorimeter value (Xunerth and D'Appolonia 1985; D'Appolonia 1987). The farinograph is an imitative instrument and its measurements are empirical (Menjivar 1990). Mixing time indicates the amount of work input needed for optimum development of the dough, whereas stability and. MTI determine the additional work the dough can withstand before deterioration of its properties, i.e. before dough break down (Runerth and D'Appolonia 1985). FA is the amount of water needed by the dough to reach a fixed consistency 29 at the arbitrary 500 Brabender unit line (AACC 1983). Xunerth and D'Appolonia (1985) indicated that FA may differ from the optimum baking absorption particularly for flours of high damaged starch content. The valorimeter value has been used as an index for flour strength and is determined by the optimum mixing time and the slope of the descending part of the farinogram (Pomeranz 1987). Wheat flour can be classified according to its development time to short, medium, or long (D'Appolonia and Xunerth 1984). Also, flours can be classified according to their dough stability into short or long. Soft wheat flours are usually of law FA, short development time, and short stability in comparison with flours of hard wheats. Pyler (1988) indicated. that gluten. proteins contribute to ‘the rheological properties of the dough. MacRitchie (1978) reported from flour reconstitution studies that the protein fraction gliadin decreased dough strength and mixing stability. The high molecular weight insoluble protein fraction glutenin increased farinograph development time and reduced farinograph dough breakdown time. Flours milled from the same wheat at different rates of extraction may show different dough properties. Rheological measurements using the farinograph for two flours which were milled from the Egyptian soft wheat variety, Giza 157, to 82% and 73% extraction showed that these flours had FA of 72.5 and 65.5%, respectively; dough development time of 1.50 and 1.00 min, respectively; dough stability of 1.50 and 1.75 min, respectively; and dough weakening values (MTI) of 150 and 140 B.U., respectively (Abu El-Azm 1989). The rheological properties of a hard wheat flour of 72% extraction obtained from the Egyptian Ministry of Rationing, Cairo, Egypt were measured by Abd El-Latif et al (1986) using the farinograph. The flour had 66.3% FA, 6.5 min peak time, 7.7 min dough stability, and 47 B.U. MTI. Hamed et a1 (1973) used a flour of 72% extraction.which had 12.16% protein and 0.49% ash content (d.b.) and had been imported to Egypt for baking 30 Balady bread. Their farinograph study showed that the flour had 59.3% FA, 2.0 min development time, 3.0 min stability, and 40 B.U. MTI. The wheat varieties Baladi and Hindi which had been traditionally used in Egypt for baking Balady bread were found by Refai et al (1962) to have week gluten characteristics as was indicated by sedimentation and farinograph tests. The farinograph absorption of 50.5 and 58.8%, and mixing time of 0.9 and 1.56 min were reported for the 70% extraction flours of Baladi and Hindi wheat varieties, respectively. Faridi and Rubenthaler (1983b) studied the rheological properties of 82% extraction flours milled from soft white, soft red, club, hard red winter, and Australian wheats. Balady dough absorption for these flours were>measured by adjusting the farinograph traces at the 200 8.0. line and were found in the range of 71-83%. Stronger wheats showed higher water absorptions. Mousa et al (1979) studied the rheological properties of HRS and HRW flours of 85, 90, and 95% extractions using the farinograph. The 90% extraction flour, for example, of the HRS and HRW varieties had 67.3% and 63.6% FA, 5.0 and 4.5 min development time, and 10.0 and 7.5 min stability, respectively. El-Minyawi and Zabik (1981) reported 58.7% FA, 3.6 min peak time, and 33 8.0. HTI for a 74.5% extraction HRW wheat flour as determined by the farinograph. The Nixograph Test The mixograph is also a recording dough mixer; however it applies higher speed and runs without any temperature control (Pomeranz 1987). The mixograph has been used to measure dough quality factors such as absorption, mixing time and mixing tolerance (D'Appolonia 1987). Optimum mixing time is defined by the time of mixing required until the curve reaches its peak. Pomeranz (1987) indicated that dough mixing time as measured by the mixograph is more highly correlated with experimental bake mixing time than that measured by the farinograph. Mixing tolerance is 31 indicated from the slope of the curve beyond the peak, whereas dough strength is judged from the nuxogram peak height and magnitude of the weakening angle (Finney and Shogren.l972). Runerth and D'Appolonia (1985) indicated that the farinograph MTI and the mixograph weakening angle or curve height after a certain time from the peak provide information about dough tolerance to mixing beyond maximum consistency. Finney and Shogren (1972) discussed the relationship between bread dough handling properties and mixing requirements using the standard mixograph procedure. Dough of short mixing time (1.5 min) is more likely to be less stable, less elastic, and more extensible than one of longer mixing time. They also indicated that dough extensibility decreases as dough mixing time increases, whereas stability, elasticity, and mixing tolerance increase. But, as mixing time becomes far longer (>4-5 min) the dough becomes ”bucky” and loses its appropriate degree of elasticity and extensibility. Changing water content of the dough affects its properties as measured by the mixograph. Increasing water absorption of a HRS flour from 60% to 80% by 5% increments resulted in a continuous increase in the mixing time required for optimum dough development and a continuous decrease in dough consistency as measured by mixograph development time and peak height, respectively (Kunerth and D'Appolonia (1985). Finney (1989) reported that differences in mixograph measurements among flours of similar protein content are related to differences in the inherited protein quality. The author also indicated that mixograph mixing time increases continuously as flour protein increases till 12% protein content, and decreases thereafter. Within a wheat variety, mixograph absorption, however, increase continuously as flour protein content increases. The author concluded that mixograph mixing time and water absorption are functions of both flour protein content and quality. Mixograms of a HRW wheat flour of 74.5% extraction and of 58.7% absorption showed 3.72 min peak time, 6.08 cm peak height, and 81.86 cm? 32 area under curve (El-Minyawi and Zabik 1981). Faridi and Rubenthaler (1983b) reported that flours from soft white and club*wheat produced dough of similar strength when tested by the mixograph at water absorption levels previously determined by the farinograph at the 200 B.U. fixed consistency. In contrast, flours from hard red winter and soft white spring wheats produced relatively stronger doughs. The Extensigraph Test This is a load-extension instrument that provides information complimentary to those obtained by recording dough mixers such as the farinograph (Pomeranz 1987). In this test, a piece of dough is shaped into a cylinder, mounted on a holder, and stretched from the middle until rupture (Bloksma and Bushuk 1988). D'Appolonia (1987) indicated that the force-time curve produced by the extensigraph is evaluated for dough properties such as dough extensibility, resistance to extension, area under curve, and proportional number (The proportional number is calculated by dividing dough resistance to extension by extensibility). The test has been used to study the effect of flour improvers such as oxidizing agents on dough properties (Pomeranz 1987). These dough properties are attributed to the gluten proteins. Gluten extensibility is a wheat varietal trait (Pratt 1978). MacRitchie (1978) reported that adding the high molecular weight insoluble protein fraction glutenin to a reconstituted flour increased height (dough resistance to extension) and area (dough strength) of the extensigraph. Abu El-Azm (1989) used the extensigraph to measured some of the rheological properties of doughs made from 82% and 73% extraction flours which had been milled from the Egyptian soft wheat variety Giza 157. The 82% and 73% extraction flours had values of 146 and 140 mm for dough extensibility, and of 320 and 500 8.0. for dough elasticity. The respective values of the two flour doughs for the proportional number were 2.2 and 3.6 B.U./mm. It is shown from these data that, as flour 33 extraction rate increased, dough elasticity greatly decreased, while dough extensibility slightly increased. The Alveograph Test The alveograph has been used to study the behavior of a sheeted piece of dough upon forcing air to blow it up like a bubble until rupture. The air pressure inside the dough.bubble is recorded against time (Bloksma and Bushuk 1988). The curve may explain dough strength and gas retention capacity. Bloksma and Bushuk (1988) indicated that alveogram height represents dough resistance, whereas its length at the base represents dough extensibility. Alveogram length was found to be highly correlated with western pan bread loaf volume (Pomeranz 1987). Refai et al (1962) studied some of the chemical and physical characteristics of some commercial and new Egyptian wheat varieties cultivated at different locations and evaluated their suitability for Balady bread-making. The authors suggested that flours to be used for making Egyptian Balady bread should possess these alveograph values: 70-90 mm for dough stability and 15-20 cm2 for dough strength. Those varieties which were considered fit for bread-making were of weak or medium gluten quality as determined by the farinograph test and sedimentation test. Alveograph test of Hindi flours from different locations showed dough strength, stability, and stretchability to average between 10.0-19.8cm2, 61.6-95.7m, and 26-42 m, respectively. Hamed et al (1973) used a flour of 72% extraction for baking Balady bread. Their Alveograph study showed that the flour had dough strength of 45 cu?, extensibility of 88 mm, and resistance to extension (R) of 98 mm. The calculated proportional number (PN) for that flour was 1.0. Hamed et al (1973) mentioned that an alveograph proportional number no lower than 0.7 is required in Balady bread. 34 The Oscillatory and Viscoeetry Tests In oscillatory tests, the dough sample is subjected to very small stresses resulting from imposing very low strains that vary sinusoidally with time (Bloksma and Bushuk 1988). Parallel plate or coaxial cylinder viscometers are popular instruments for running these dynamic tests (Faubion and Hoseney 1990). Through these dynamic tests, the elastic and viscous components of the dough viscoelasticity and their ratio can be measured (Faubion and Hoseney 1990). The authors indicated that wheat dough possesses a nonlinear viscoelastic behavior, and starch contributes, in part, to this nonlinearity. The authors also described and explained the role of mixing, water content, f1our components, fermentation, and heat on dough properties as measured by these dynamic ”fundamental” rheological tests. Bloksma and Bushuk (1988) indicated the usefulness of the oscillatory measurements in studying dough properties using conditions which barely alter dough structure under the small magnitude of the applied stress. However, studying dough behavior under larger magnitude of deformation (such as those of viscometry tests) is equally important and needed to understand dough reactions to stress during comercial production. Weipert and Pomeranz (1986) studied the rheological properties of wheat whole grain meals and flours using a viscometric method‘with.a Haake Rotovisoo Rv-3 instrument in relation to their protein content, water absorption and breadmaking properties. As shear rate was increased continuously by 2.5 rpm/min, the measured shear stress increased until it reached a maximum value after which it decreased. Thereby, the authors stated that wheat dough is a viscoelastic fluid and has shear-thinning characteristics. Because of this nonlinear viscoelastic behavior, comparison of viscosity of different doughs is valid only if measurements are made at the same shear rate. 35 The point on the flow curve at which the shear stress started to decrease indicated comencement of dough structural breakdown and was called the tear point (Weipert and Pomeranz 1986). Two measurements were related to dough properties and breadmaking quality: The apparent shear rate at the tear point and the viscosity index at the characteristic shear rate. Doughs made from flours of good pan bread baking quality and of desirable dough handling properties produced steep flow curves of low critical shear rate at the tear point, and high values for shear stress and viscosity index (Weipert and Pomeranz 1986). Flours of high protein and/or damaged starch contents, and thereby, of high water absorption capacity produced doughs of large consistency and flow curves of high values of viscosity index and shear stress at the critical shear rate and lower values for critical shear rate at the tear point. The Back Extrusion Test The back extrusion test has been used successfully to measure the rheological properties of different food systems such as mashed potato (Schweingruber et al 1979), sorghum doughs (Subramanian et al 1983), thermally coagulated protein gels (Harper et al 1978; Hickson et al 1982), aqueous methocel and sodium-calcium alginate (Osorio and Steffe 1985a,b), and starch gels (Dolan et al 1989). In some of these studies, the authors utilized various mathematical models to describe the rheological properties of the material under investigation based on the back extrusion data. The others, however, used some of the measured parameters of the force-time curve such as curve height, slope, and area as simple rheological indices. In the back extrusion test, the sample is placed in a vertical container and a plunger is forced to move downward through the sample at a constant speed. The sample flows upward through the gap between the plunger surface and the inner walls of the container. The force on the plunger surface is measured and can be considered as a relative 36 rheological property (Morgan et al 1979). Direct measurements such as height, slope, and area of the back extrusion curve have been also used to describe rheological properties of the tested material (Schweingruber et al 1979; Subramanian et al 1983). Mathematical equations for calculating rheological properties such as viscosity for Newtonian fluids and‘viscosity index, apparent viscosity, and apparent elasticity for nonNewtonian materials from the back extrusion data have been developed (Morgan et al 1979; Hickson et al 1982; 0sorio and Steffe 1985a,b; Dolan et al 1989). The relaxation time constant(s) can also be calculated by monitoring the residual force after the plunger movement has stopped (Morgan et al 1979). 'The back extrusion technique has many advantages. The test is simple, easy, quick, and reproducible (Morgan et al 1979). It allows for variability in sample preparation, composition, size, and testing conditions (Morgan et al 1979). It can be used in quality control and product development programs (Steffe and 0sorio 1987). Interfacing the instrument with a computer will speed up data collection and handling (Steffe and 0sorio, 1987). The back extrusion test on the Instron testing machine was used, along with other viscometric tests, by Schweingruber et al (1979) to evaluate some of the rheological perameters of instant mashed potato. Height of the back extrusion curve, which was used as an index for consistency, was highly correlated (r>0.9) with values of Brookfield viscometer and with the yield stress measured on the rotational coaxial viscometer. The back extrusion test was also used by Subramanian et al (1983) for evaluation of some textural properties of sorghum doughs using the Instron. The back extrusion unit consisted of a sample vessel of 35mm i.d. and 95mm height, and a plunger fitted with a circular disc of 34mm diameter and 9mm height. The test was run at 50 mm/min crosshead speed. Eight sorghum cultivars of varying dough kneading properties were 37 evaluated. On a 1-3 scale, the kneading quality was scored subjectively by the ease with which the dough can be rolled by a rolling pin or flattened by hand into a disc. Sorghum dough should be fairly cohesive and resilient in consistency in order to produce high quality Roti, a coarse, unleavened type of bread. The force distance curves were evaluated for the following parameters: The compression-extrusion force, slope of the curve, and area under curve. The back extrusion results confirmed with the subjective evaluation of dough cohesiveness. Subramanian et a1 (1983) found that force, slope, and area of the back extrusion curve increased as dough cohesiveness increased. The authors indicated that the back extrusion test showed a great potential in the differentiation among sorghum doughs of different kneading quality. The authors recommended using the slope of the back extrusion curve as an index for sorghum dough cohesiveness. Balady Bread Characteristics and Evaluation In Egypt, Balady bread is produced and distributed on a commercial scale (Edwardson and MacCormac 1984). It is made from a high extraction flour (85-95%) of 10-12% protein content (Mousa et al 1979), and soft white wheat is preferred to other wheat classes (Faridi and Rubenthaler 1984). Balady bread is one of the most popular breads produced in Egypt and some of the surrounding countries in the Middle East. It is a unique baked product because of its simple formula and special characteristics (Faridi 1988). Two of its major characteristics are the high water absorption of the dough (usually 75-85%) which renders the dough a consistency of a batter, and the high temperature and short time (about 500-600qC for l min) of baking (Faridi 1988). Hamed et al (1973) reported that Balady bread can also be baked at lower temperature (350°C) for longer time_ (2-3 minutes). Balady dough is prepared using a straight dough procedure and ‘the» formula (on flour' basis) is very simple; a. high 38 extraction flour (BO-95%), a large amount of water (70-80% of flour), a small amount of table salt (0.5-1.5%), and a fermenting agent such as yeast or a mother dough (12—17%) (Hamed et a1 1973; Mousa et a1 1979; Faridi and Rubenthaler 1983b; Morad et al 1984; Faridi 1988). The bread is hearth baked and has an attractive aroma and flavor (Faridi 1988). Wheat Classes and Extraction Rates Faridi and.Rubenthaler (1982) indicated that the flat type breads can be produced from any type of wheat flours. However, flour with strong gluten forming potential is not desirable and mechanical break down (over- mixing) of the gluten networkLmight be necessary to produce quality bread. Soft wheat is preferred in producing Balady bread (Faridi and Rubenthaler 1984; Morad et al 1984). Refai et a1 (1962) studied the chemical and rheological characteristics of some commercial and breeder lines of wheats grown in Egypt. The wheat varieties, Baladi and Hindi, which have been used for commercial Balady breadmaking, and have been used traditionally in Egypt for baking Balady bread were found to have weak gluten characteristics as was indicated by the sedimentation test and farinograph test. The 70$ extraction flours of Baladi and Hindi had a protein content of 7.1% and 8.1% (14‘ m.b.), respectively. The flour from the Hindi variety was categorized as being of medium gluten strength when tested by the fermentation time test, whereas Baladi wheat variety was ranked in the weak gluten category. Faridi and Rubenthaler (1983b) compared Balady bread made from flours milled from different wheat classes (soft white, soft red, club, hard red winter, Australian) at 82% extraction. ‘The authors found‘wide differences in baking performance and rheological properties among varieties. They concluded that flour performance was independent of flour protein. The authors recommended further research to elucidate factors in the control of flour performance in Balady bread baking. 39 Flours from strong*wheat classes have a carrying power, i.e. they can be blended with flours from weak varieties or non-wheat sources for economical or nutritional purposes. Finney et al (1980a) used a comercial wheat flour of "good loaf volume potential, and of medium mixing and oxidation requirements" to produce Balady bread; the flour had 11.67% protein. Up to 20% replacement of that flour with flour from ungerminated decoated faba beans produced acceptable Balady breads of improved nutritional value. El-Minyawi and Zabik (1981) baked Balady bread from HRW flour of 85t extraction substituted with different levels of liquid cyclone processed cottonseed flour. Acceptable Balady breads were produced at 12% or lower levels of substitution. Morad et a1 (1984) used a HRS flour of 723 extraction to produce Balady bread fortified with sorghum flour. Fortified Balady breads were acceptable up to 308 substitution. Mousa et a1 (1979) used HRW and HRS flours of 85, 90, and 95% extractions in baking Balady bread. The 90‘ extraction flour had the average protein and ash content of 12.3 and 1.1%, respectively. The HRS and HRW flours of 90% extraction contained, respectively, 30% and 32.4% wet gluten (14% m.b.). The authors reported that flours of higher extraction required more baking water absorption. However, Balady breads baked from all flours were acceptable regardless the level of extraction. Balady Bread Making Process In the Balady baking process in Egypt, dough pieces of about 2009 each are cut from a dough fermented in bulk, shaped into a ball, placed on wooden trays covered with fine bran, and left for a second fermentation period. Then the dough is flattened by hand to 5-7 mm in thickness and baked at 9009F (482°C) for 2 minutes in an open hearth oven (Dalby 1963). The baked loaf weighs 1709 and has a diameter of 15-20 cm. Hamed et a1 (1973) baked Balady bread in a professional bakery in Egypt. They reported that a 1459 dough piece was used and was flattened 40 by hand and baked at 350°C for 2-3 minutes. They indicated that, despite the high amount of water in the dough formula, the moisture of the baked loaves was generally less than 40‘. More recently, Faridi (1988) also described the bread making process in Egypt based on a survey made in 1985. Balady bread is produced comercially from wheat flour of high extraction (BS-100%) and water absorption of 70-80%. A small amount of table salt and a source of yeast (regular yeast of sour dough) are the other ingredients in the formula. A straight dough procedure is used. After mixing all the ingredients, a 90 nunute fermentation period is given. The dough is slack and has a consistency of a batter. Fermented dough is scaled by hand, shaped into balls, flattened into a pancake shape, given a 30 minute proof time, and then, hearth baked at about 500%: for 40-60 seconds. under such high temperature, the developed steam, rather than the expansion of carbon dioxide, will puff up the flat dough by forming a large pocket which separates the loaf into two layers. The loaf is mostly crust with a small amount of crumb. The baked loaf is circular in shape, 7-10 cm in height at the center and around 150 g in weight. After cooling, the loaf may fall back to its characteristic flat shape. The pocket of the loaf can hold other foods used as fillers for making a sandwich that can be eaten without the need for using eating utensils. Balady Eread Evaluation There has not been a common standard baking test for Balady bread. Published reports on Balady bread baking and evaluation procedures, applied different standards for dough preparation, handling, and baking conditions. Also, various objective and subjective techniques were used for evaluation of the baked Balady bread. Regardless of the inadequacies of some of these evaluation techniques, all researches agreed on the 41 importance of the following bread criteria: puffing (or pocket formation), texture, and color. Subjective Evaluation: Hamed et a1 (1973) ran a sensory test for an evaluation of Balady bread made from flours of 72% and 93.3% extraction to which sweet potato flour had been added at different levels. Panelists eva1uated the bread for these three characteristics (10 points each): crumb color, taste, and appearance which was a combined evaluation of symmetry, grain, and texture. The total score which had a maximum of 30 was used for the comparison among breads baked from different flour blends. Neither the score card nor a specific description of these characteristics was reported. Mousa et al (1979) evaluated the bread on a 1-10 scale also, but using these criteria: crust color, crust thickness, crumb color, crumb texture and grain, flavor, and mastication. The score card had a straight-line scale for each criterion with extreme off-characteristics located on both sides of the scale, whereas the "ideal” characteristic was located near or at the middle of the scale. The authors described the ideal characteristics for the bread criteria as follows: crust color is golden brown, thickness of the crust is medium or slightly thicker, crumb color is creamy or slightly darker, crumb texture is medium open, flavor and taste are pleasant, and.mastication is chewy. For each criterion, an arrow was placed on the scale pointing to a location that should be given had the bread met the ideal descriptions for such criterion. The absolute deviation of the panelist's mark from that of the ideal were summed over all criteria to obtain a relative rating of the quality. Using this evaluation procedure, the lower the value the better was the bread. Bread baked from flour with no additives (oxidant and malt), using a straight dough method, was better than that baked using continuous methods or when the dough was treated (Mousa et al 1979). 42 According to Mousa et a1 (1979), the optimum crust color is golden brown, but the color may range from pale to dark brown. Layer thickness was evaluated as the ”crust character" and had a range from thin to thick with an optimum value that was located at the middle of the range slightly toward the lower side of the range. Crumb color ranged from white to brown with the creamy color at the middle of the range. However, the brownish creamy color is the optimum. El-Minyawi and Zabik (1981) conducted a sensory evaluation test on baked Balady bread using 6 trained Middle Eastern panelists. Bread was evaluated for crust color, crumb color, flavor, texture, aroma, and general acceptability. A seven-point descriptive scale was used. The crust color scale ranged from 1 (very dark brown) to 7 (light tan), and crumb color scale ranged from 1 (greenish dark yellow) to 7 (oatmeal color). The scales of the other characteristics were similar in that each ranged from 1 (very poor) to 7 (excellent). Panelists comments were also considered by El-Minyawi and Zabik (1981). Faridi and Rubenthaler (1983b, 1984) used the following criteria for sensory evaluation of Balady bread: degree of separation of top and bottom crusts, thickness of top and bottom and their ratio, crumb characteristics (soft, white, and moist), and crust characteristics (shiny with brown spots). The scoring was made on a 1 to 10 numerical basis, *where 1 meant very poor and 10 meant excellent. The mean value of each factor was converted to descriptive categories, namely: excellent (9-10), satisfactory (7-8), questionable (5-6), and unsatisfactory (less than 5). Faridi and Rubenthaler (1983b) indicated that crust contributes significantly to the’overall quality and that pocket formation is critical for Balady bread. Other characteristics of the bread are equal thickness of upper and lower crusts. The crust should have a uniform, desirable color. The crumb should be soft, uniform in texture and grain, and light in color. 43 . Morad et a1 (1984) used bread puffing and layer separation as the only subjective criterion for evaluation of Balady bread. Evaluation was done by the authors themselves. Finney et al (1980a) used a panel of 10 untrained Egyptian students to evaluate Balady bread baked from wheat flour or wheat flour mixed with 0t to 30% ungerminated faba flour, for the following characteristics: taste, color, puffing and layer separation, and crust to crumb ratio. ‘Acceptable Balady bread*was produced from‘wheat flour replaced with up to 20% decoated faba bean flour. Mohsen et al (1986) used wheat flour of 87.5% extraction to study the effect of adding lipase on the staling of Balady bread. Balady bread baked from untreated and lipase-treated flours was organoleptically evaluated for color, taste, and crumb texture as well as for freshness after 24 hours from baking. Fresh bread made from treated and untreated flours scored the same by the panelists, but breadlmade from flour treated with lipase scored better by the panelists after 24 hours storage. Objective Evaluation: Loaf diameter, volume, weight, and specific volume are some of the objective measurements used for evaluation of Balady bread. Shehata and Fryer (1970) and El-Samahy and Tsen (1981) reported 5.46 and 5.78 cc/g, respectively for Balady specific loaf volume. Higher values up to 12.0 cc/g were reported by Mousa et a1 (1979). El- Shimi et a1 (1977) found that specific loaf volume increased as wheat flour strength increased. Faridi and Rubenthaler (1983b) indicated that the loaf volume of flat bread is not the crucial criterion in bread evaluation as is the case for pan bread. El-Samahy and Teen (1981) found that the loaf weight decreased and specific volume increased as the loaf baking temperature was increased at a constant baking time. Those authors gave the baked bread an extra heat treatment (149°C for 10 minutes) to harden the loaf before measuring its volume by the seed displacement procedure. Mousa et al (1979) mentioned that in order to measure loaf 44 volume by rapeseed displacement, bread was left to dry out at room temperature for one day in order to harden the surface. Mousa et a1 (1979) stated that large loaf volume is desired for Balady bread, but the Egyptian Food Administration requires constant loaf weight. Baking the bread at high temperature reduced loaf weight and increased loaf specific volume. The temperature-time combination should be controlled to maintain legal specification and to produce quality Balady bread. The texture of Balady bread was evaluated subjectively using different equipment. El-Minyawi and Zabik (1981) used the Instron to evaluate bread tenderness. The Instron was equipped with a single blade tenderness test cell. The shear force required to cut through a 5 cm sample slice was used as an index for bread tenderness. Faridi and Rubenthaler (1983b) used a Fudoh Rheometer fitted with a 0.29 mm diameter wire to cut through a 1 cm bread slice. Pressure measured in 9/cm was used as an index (rheological value, RV) for bread texture. The higher the value the tougher the bread. Bread having higher RV was also ranked lower in crumb texture by the panelists and was described as rubbery. Mohsen et al (1986) used a modified Instron method to test Balady bread strength. The method measures the force in pounds required to compress 1 cm height samples. Bread made from untreated flour was stronger than that made from flour treated with lipase. The reduction in bread firmness, brought about by the action of lipase, was related to the partial hydrolysis of mono- and diglycerides from‘wheat oil. The test was also used to follow bread staling. Bread made from flour which had not been treated with lipase showed higher Instron values after 48 hours of storage than those made from treated flour. The Instron force at 0, 24 and 48 hours storage indicated that staling rate was slower in the first 24 hours after baking than in the next 24 hours. The color of bread crust and crumb was given great attention during Balady bread evaluation objectively and subjectively. El-Samahy and Tsen 45 (1981) measured the color of the top and bottom crusts using an Agtron multichromatic abridged reflectance spectrophotometer (585 nm; yellow). when baking time was kept constant, top crust color values decreased, i.e. became darker, as baking temperature was increased. Color values of the bottdm layer followed the same trend. The top crust color values showed greater variation than those of bottom crust. The color values of high quality bread were 51.8 and 48.5 Agtron units for top and bottom crusts, respectively. Faridi and Rubenthaler (1983b) also used the Agtron test to evaluate the color of the 82% extraction flours milled from different wheat classes. However, color of Balady breads baked from these flour was not evaluated objectively. Morad et a1 (1984) used a Gardner Color Difference Meter adjusted with the standard tile (L - 77.3, a - -1.7, and b . 22.8). The L value (degree of lightness) of the Balady bread baked from 100% and 72% extraction flours were 48.2 and 68.9, respectively. They mentioned that white color is not required for quality bread but this color is preferred. Ultrastructure of Dough and Bread Systems Electron microscopy has wide applications in the area of cereal science and technology. Several studies had been conducted to study the ultrastructure of wheat components, their interaction, and functionality. Studies on wheat kernel structure (Evers and Bechtel 1988), milling of wheat into flour (Davis and Eustace 1984), and transforming the flour into dough and bread (Rhoo et a1 1975; Fretzdorff et a1 1982; Bechtel 1985) have revealed structural differences among wheat varieties, wheat components, dough, and baked bread. Differences in the milling pattern among wheat classes, for example, were revealed by scanning electron microscopy (SEM) of flour milling fractions. Davis and Eustace (1984) reported that soft wheats showed 46 different milling pattern in comparison with hard wheats. The endosperm of soft wheats separated easily from the bran and milled rapidly into fine flour. The SEM provides a three-dimensional view of the topography of specimen surface structure, whereas the transmission electron microscopy (TEM) supplies detailed information regarding specimen internal structure. The TEM requires sample fixation, dehydration, embedding, and thin sectioning. Regular SEM requires sample fixation and/or dehydration, however, the low-temperature SEM (Cryo-SEM) does not require such steps because samples are examined in their hydrated state. Cryogenic preservation of the structure through cooling the specimen in liquid nitrogen slush and viewing under Cryo-SEM at -160 to -170°C was used for studying dough systems (Lorimer et a1 1991; Berglund et al 1991) and wheat gluten (Freeman et al 1991). While samples are in the frozen state, they may be fractured and coated with gold to reveal the interior structure. In another electron microscopy technique, replicas of freeze-fractured surfaces of the frozen dough samples are made and examined using the transmission electron microscope (Fretzdorff et al 1982). Techniques of sample preparation for the electron microscopy studies have a great impact on the preservation of the original structure and clarity of fine details of the sample (Pomeranz 1987). Pomeranz (1987) indicated that chemicals used during fixation and dehydration of dough and bread samples are known to alter the protein matrix leading to disclosure of the starch granules that were enclosed within the matrix. The author also indicated that the freeze-fracture technique minimizes the number of possible artifacts particularly when chemicals normally used in sample fixation and dehydration are avoided. Scanning electron microscopy (SEM) of dough structure: The ultrastructure of flour-water dough was studied by Evans et al (1981) using SEM. Doughs mixed for the optimum mixing time showed even 47 distribution of the starch granules through the dough surface. ‘The gluten formed a continuous veil-like structure in which the starch granules were embedded. The protein film was thinner in areas covering the starch and was thicker in other areas. The gluten surface contained small pores (<1.5 pm in diameter) and were thought to be locations of lipids or volatiles. Difference in the ultrastructure among flour-water doughs (El-Minyawi 1980), and of gluten protein (Freeman et al 1991) were found as a result of using different sample preparation techniques. Techniques which included chemical fixation, dehydration, and critical point drying introduced profound effects on dough structure as was seen by SEM (El- Minyawi 1980). The protein films were discontinuous, fibrous, and thick, and contained some air vacuoles. The starch granules were not completely covered with the protein matrix. The difference in the two micrographs was explained by possible denaturation of dough proteins during sample preparation. The other preparation technique used by El-Hinyawi (1980) included freezing the sample in liquid nitrogen followed by freeze-fracture and freeze drying. Micrographs of flour-water doughs showed thin protein films that were smooth and continuous, and were enveloping the starch granules. The later technique was also used by Belitz et al (1986) to study gluten preparations using SEM. Belitz et al (1986) reported that micrographs of wheat gluten exhibited porous and continuous web-like structure. The reticular pattern in the protein network was evident. Role of mixing on the ultrastructure of flour-water dough was also studied by Evans et a1 (1981). Micrographs of undermixed the dough indicated incomplete development and discontinuity of the gluten structure. Starch granules were irregularly grouped in some areas and were partially covered with gluten. Overmixing showed evidence for gluten break down» Micrographs of the overmixed doughs indicated that the gluten became discontinuous and was pulled away from starch granules. The later 48 were no longer attached tightly to the gluten matrix and were surrounded by large gaps. The effect of imposing stress on the flour-water dough was also studied by Evans et a1 (1981). Upon stretching the dough, gluten formed thin fibrils that were oriented in the direction of stretch. The ability of gluten to form fibrils increased during proofing the dough (Evans et a1 1981). 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I In 5505: soon 5055: 5555555> -uuun----uuuuuuuuuuuuuuuuuuuuuu .5555: oceum Assam loan escaueooa oranueooa usueque> neceucoo cueuoum «55555555> 5555: 555553 5555 55555 or» 50 55555 or» 50 555553 55505 as. ousuu5ox .ocs ocean ususqus> or» o» eeusnuuucoo unequsooa .sco—ueeoa ocuzouu .cueuoum necuex ease: N manta 60 Inc. Appropriate changes were made on the mill settings so that the normal flour extraction rate which averages 73% would increase to the highest extraction rate possible. The changes are noted on the Miag flow sheet (Figure 1). The original roll spacings were 508, 127, and 76.2 micron for the three break rolls, and 114.3, 88.9, 63.5, 38.1, and 38.1 micron for the five reduction rolls. The roll spacings for the break rolls were changed to 381, 76.2, and 38.1 micron. The screens used for normal sifting were kept the same except for the first pairs of screens on top of the sifter boxes located below the three break rolls and the first middling (reduction) rolls. The original pairs of screens below the first, second and third break rolls were of 869, 787, and 716 micron, respectively. These were replaced by pairs of screens of 1041, 1184, and 1359 micron, respectively. The original pair of screens below the first middling rolls were of 470 micron. The top one was replaced by a 119 micron screen, while the one next to it was removed without replacement so that the materials would not go back to the third break rolls. After the adjustment, the yield ranged from 83.4% to 86.0% with an average of 83.9% for the eight SWW varieties (Table 3). Table 3 shows the data provided by Mr. L. C. Andrews, (SWQL) regarding the mill fractions (expressed as percentage of total mill yield) obtained from the Miag mill. These fractions represent shorts, bran, and extracted flour. As the goal was to get 90t extraction, the bran was passed through the sixth break rolls of the Allis-Chalmers mill (24 corrugations per in., roll spacing of 12.7 micron), then, was sifted over a 54 mesh screen. The coarse bran fraction was discarded and the final bran fraction was combined with the shorts fraction from the Miag mill, and subjected to further particle size reduction through the sixth break rolls of Allis Chalmers mill and sifted over a 60 mesh screen. 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New. 2: .5-... 5;; 3; m5. 555 r; .Nm 55. -ew. {xi} .3... m ; 3.5M... .5... 5H fig :2 swap .- 55 @Pd: .Kdn Qua: 93b 9 .DH 5:. 5... 3.5 5.5 5... _...5 .=. 5 5.. . ..||: qluwl 5555:: 555:: 62 TABLE 3 Milling Data of the Eight Soft Winter Wheatsa Whole Finalb Wheat Kernel Feed Flour Extr. Variety Moisture Rate Bran Shorts Extracted Rate (*) (lb/hr) (*) (*) (*) (%) Red Varieties Adena 12.8 103.8 1.53 14.48 83.99 90.0 Auburn 13.3 111.5 1.95 14.47 83.58 90.0 Caldwell 13.5 111.3 1.81 14.54 83.65 90.0 Charmany 12.8 85.7 2.61 14.01 83.38 90.0 Hillsdale 12.8 100.7 2.19 14.21 83.60 90.0 White Varieties Augusta 13.3 89.4 3.09 13.11 83.80 90.0 Frankenmuth 13.8 91.1 3.03 13.55 83.43 89.9 Tecumseh 13.0 ___¢ 0.99 13.02 85.99 90.0 D’D Data were supplied by the Soft Wheat Quality Lab., Wooster, OH. The final extraction rate (90%) was made possible by adding to the flour (extracted by the Miag mill) the proper amounts of the bran and shorts fractions (after reducing their particale size through milling on Allis Chalmers mill and sifting over a 60 mesh screen). Not determined. 63 to be added to the original flour extracted by the Miag mill to make up for the 90% extraction sought. Rheological Study Methods Farinograph studies The AACC constant dough weight procedure (AACC 1983, Method 54-218, Approved April 13, 1961) was used to study the flour-water dough rheological characteristics and to prepare dough samples for the ultrastructure study using the Scanning Electron Microscope. The Farinograph model PL-2H (C.W. Brabender Instruments, Inc., S. Hackensack, M.J.) was equipped with a Dynamometer (type Pl—lH), a 50 g mixing bowl (type S50), and a Thermobath (type P60-B). The mixing bowl temperature was kept constant at 30 t 0.1°C. The amount of flour used for each test varied according to flour moisture and the amount of water required to center the curve on the 500 Brabender Unit (B.U.) line. Curve adjustments for all eight SWW flours were made according to the AACC Table 54-28 A (AACC 1983) so that the final dough weight of each of the eight SWW flours was a constant 80 9. Preliminary tests were made for each flour to pick up the proper water absorption necessary to center the curve at the point of maximum dough consistency on the 500 B.U. line. After the water absorption was determined, the test was replicated twice. Flour was weighed to the nearest 0.1 g, transferred into the mixing bowl, and allowed to premix for 1 min after which the appropriate amount of water was delivered‘within 20 sec while mixing continued at 63 rpm. The Farinograph curves were evaluated according to the following measurements: Water absorption, arrival time, peak time, stability, departure time, mixing tolerance index and breakdown time. ' 'The Farinograph was also used to study the dough characteristics when mixed at the water absorption optimized for Balady bread baking (Table 4, in the Balady bread baking section). These later curves were run without 64 adjustment to the 500 B.U. line as would be done in the conventional Farinograph test. Three replicates were made. In this case, all previously mentioned measurements were made on the curve after drawing a horizontal line parallel to the 500 B.U. line passing through point of maximum consistency of the curve. Curve height was also noted. Mixograph Studies The purpose of this part of the study was to evaluate the mixograph rheological properties of flour-water dough of the eight SWW varieties. The AACC procedure 54-40 [Approved April 13, 1961] (AACC 1983) was applied using a Mixograph (National Mfg. Co., a 35 g mixing bowl model) equipped with a mixograph strip paper recorder. The optimum water absorption required to produce the AACC conventional mixograph trace for each of the SWW flour samples was decided in consultation with Dr. P. Finney, SWQL, Wooster, OH, after inspection of mixograms made by running preliminary mixograph tests at the SWQL, Wooster, OH utilizing a 10 g flour samples at different water absorption levels (Finney and Shogren 1972). Mixograms also were obtained using the conventional AACC procedure, using the water absorption optimized for Balady breadmaking '(Table 4, Balady bread baking section), and using three fixed‘water absorptions (60, 65, and 70%). Mixograms were evaluated for the following measurements: Peak height, peak time, height at 8 min, and area under the curve. At each water absorption level, two replicates were made except for the water absorptions optimized for Balady breadmaking; three replicates were made. Back-extrusion study The purpose of this study was to explore the usefulness of the back- extrusion test (Morgan et al 1979) in assessing some of the rheological properties of the eight SWW*wheat flour-water doughs. The test was run at three different shear rates in order to study the effect of shear rate on the measured properties. A split-plot statistical design was utilized in 65 this study. The eight wheat flour-water dough samples were prepared in two replicates and two subsamples per replicate. Dough preparation for the back-extrusion test: Flour-water doughs at 65% absorption were mixed to optimum in a 3009 bowl mixograph. The amount of flour and water used as well as the time of mixing varied depending on flour type and moisture. Flour weight and water volume for each dough were calculated so that 2359 of final dough weight would be obtained. Dough optimum mixing time was determined according to Finney and Shogren (1972). This is the point at which dough mobility reaches its minimum during mixing and the pull on the mixograph pins revolving through the dough reaches its maximum. Had the mixing gone beyond that point, dough breakdown would have taken place which would appear from a continuous decrease in dough resistance to mixing. After mixing, the mixograph bowl was emptied on a wooden board lightly dusted with about 5 g of flour. Dough pieces which weighed 50 t 2 g were cut and packed into test tubes, 250mm height, 22.8mm i.d. while gentle vacuum of air was applied to avoid the possible formation of air pockets within the dough mass or between the dough and test tube walls. Dough specific density can be calculated by dividing dough weight by its volume. After packing the dough into the test tube which normally required 0.5-1.0 min, the tube opening was covered using Saranl wrap to minimize dehydration of the dough surface. A rest period of 25 minutes was given to the packed dough to relax and to release any energy stored during the packing process. Tubes were held vertically in a water bath kept at room temperature (211 2°C) during the rest period. Testing procedure: The Instron Universal Testing Machine equipped with IEEE-488 interface (Model 4202, Instron Cbrp., Canton, Massachusetts) was used. A 5 kg (50 Newton) compression load cell (A512-13) was attached to the Instron cross-head and a plunger; an 66 aluminum rod (45cm x 2.1cm o.d., a flat end) was hooked to the cell. The test tube containing the dough was aligned concentrically with the vertical movement of the plunger. The moving plunger was allowed to penetrate 15mm through the dough. The back-extrusion test was run under the following conditions: 1. Cross-head speed of 10, 20, or 30 mm/min which ‘ shear correspond to 3.14, 6.27, and 9.41 sec' rates, respectively. 2. Plunger radius 10.05 mm, 3. Test tube inside radius 11.4 mm, and 4. Maximum penetration of plunger 15 mm. Figure 2 shows an example for a back extrusion force-distance curve. Parameters such as curve height, slope, and area can be measured directly from the curve. Also, the Instron can be run and data can be collected manually. However, a HP-Basic programiwritten by Lever (1988) was used to control the Instron and to acquire data points from the IEEE interface every 123 milliseconds and save the data to a floppy disk. The program also calculated and printed out measurements such as the area under the curve and force at the peak, as well as slope of the curve before the peaks Dough viscosity index and apparent elasticity were calculated using the mathematical equations that were developed by Morgan et a1 (1979) and Hickson et al (1982) for the back.extrusion. Dough relaxation time is the time from the peak until curve height reaches 33% of its value at the peak. Baking of Balady Bread Baking Procedure: A micro baking technique used by Faridi and Rubenthaler (1983b) to evaluate flour performance in Balady bread baking was modified and used for the evaluation of the eight soft wheat flours. The test is simplified so that a small amount of the flour is utilized and enough bread material 67 (NEWTON) l FORCE DISTANCE (mm) OR TIME (SOC) Fig. 2. Back extrusion curve of the flour-water dough. B is the point at which the plunger movement was ceased, F1 is curve height at the peak, ABC is peak area, F2 is curve height at 30 sec from the peak, BCED is area of 30 sec after peak, and Tan 9 is the slope. 68 can be produced for subjective and objective evaluations within the shortest time possible. The Balady dough formula was: Flour 100.0 9, Yeast 0.5 9, Salt 1.0 g, and Water variable. Preliminary baking experiments were done on each of the eight SWW flours to determine the optimum amount of water to be added and the proper mixing time to be used so that suitable Balady dough is obtained from each wheat flour. During the determination of Balady baking absorption, using the 300 g mixograph, attention*was focused on increasing flour absorption to the maximum possible degree to get a dough of reasonable handling properties and well developed gluten. Such dough should also be able to withstand the bread. making process till successful baked bread is obtained. Baking water absorption and.mixing time of the eight SWW flours are shown in Table 4. These values were calculated so that final dough weight would be 235 9. Yeast suspension was made ten minutes before the test started by adding the active dry yeast to the warm water and the suspension was held at 3211°C. The required amount of NaCl was dissolved in distilled water and solution was kept at 3211°C. The flour was sifted into the 3009 mixograph bowl to which the yeast suspension and salt solution were delivered. An additional amount of distilled water was added to achieve the predetermined water absorption for each of the eight soft wheat flours. The ingredients were mixed to achieve the predetermined optimum consistency of Egyptian Balady bread dough. The resulting dough was transferred to a plastic weighing dish slightly greased with vegetable shortening. A sixty minute fermentation period was given at 32tl°C. Fermented dough was degassed and divided into three dough pieces of 759 each. A ten minute rest period was given. Each of the three dough pieces was molded gently by hand to a pancake-shape of approximately 15cm in 69 TABLE 4 Levels of Water Absorption and Mixing Time Used in Balady Dough Preparation for Baking of the Eight SWW Flours Wheat Flour Water Mixing Flour Water Variety Moisture Absorptiona Time Weight Added (’H (%) (min) (9) (ml) Soft Red Varieties Adena 10.63 60 1.2 140.0 94.1 Auburn 10.38 64 3.0 136.3 98.7 Caldwell 11.16 63 2.0 138.3 96.7 Charmany 11.14 61 1.8 140.0 95.0 Hillsdale 10.75 59 2.0 141.1 93.9 Soft White Varieties Augusta 10.19 62 1.8 137.6 97.3 Frankenmuth 10.45 60 1.5 139.7 95.3 Tecumseh 9.81 63 2.2 136.2 98.8 a Calculated on 14% moisture content. 70 diameter and 0.5 to 0.75cm in thickness. Occasionally, about 1-29 flour were used in dusting dough surface lightly during the flattening process. A 30 min proofing time (32i1°C, 88% r.h.) was given. Loaves were baked at 465 210°C (850—900°F) for 9013 seconds in an electric kiln oven (model 18FL, Olympic Kilns; Haunen Manufacturing Inc., Atlanta, Georgia). The oven was equipped with a removable double Pyrex glass door fitted in an arch to conserve heat and to allow visual observation. The oven design was suggested by Dr. G. Rubenthaler, Dept. of Food Science and Technology, Washington State Univ., Pullman, WA. Preparation of Bread Samples for Objective and Subjective Evaluations The baked loaves of bread were left for 20-30 minutes to cool down to room temperature. Then, radial cuts were made to divide the loaf into 6 equal pieces. Loaf subsamples (18 subsamples) from the three loaves of each replicate were wrapped in Saranl wrap; randomly mixed, and coded for flour and replicate numbers. Representative subsamples of each replicate were introduced to the panelists (within 2-3 hours from baking) for subjective evaluation. Other subsamples were used for objective evaluations such as puncture test, and color measurements. Other subsamples were used for further chemical analyses and ultrastructure evaluation using Scanning Electron Microscopy. Bread subsamples for chemical analyses were frozen, freeze dried and milled to pass through a 0.3 mm mesh screen after which kept frozen at about -209C. Sensory Evaluation Balady bread samples were evaluated for the following characteristics of the bread: Bread upper layer, bottom layer, inside, aroma, taste, and texture (mastication). A score card and a description sheet (Appendices A and B) were prepared to describe the excellent criteria of each of those characteristics and to collect panelists' scores of their acceptability. The test was done in accordance with the taste panel protocol and research 71 proposal entitled ”Eastern U.S. Soft Wheat in Egyptian Balady Bread- Making: Performance and Acceptability" which has been approved by the University Committee on Research Involving Human Subjects (UCRIHS) On June 1, 1987. A copy of the approval letter is included in the appendices (Appendix C). The taste panel room had individual booths equipped with a source for daylight lightening. The panelists eva1uated bread samples under daylight light and marked their evaluation values for each characteristic on an open scale 10 cm line. The left end of the scale was labeled unacceptable, the right end was labeled excellent, and the middle point on was labeled acceptable. Panelists were recruited from among the graduate students at Michigan State University. More than twenty persons attended a group meeting that was arranged to describe the project goals and objectives, to familiarize the panelists with the baked bread, to explain the evaluation procedure and scoring technique, and to present the test schedule. About thirteen individuals showed appreciable interest for participation in the test. These individuals attended the preliminary training'phass~of bread sensory evaluation. The preliminary training program extended over four panels. Balady bread samples were prepared.to cover a wide range of bread characteristics and‘were presented.to the panelists with explanation. These bread samples were prepared from a whole wheat bread flour which was bought from the local retail market, a cookie flour which was bought from Michigan State University General Store, two soft wheat flours of varying quality which were donated by Dr. P. Finney (SWQL, Wooster, OH), and some of the eight SWW flours of the actual study. The whole wheat bread flour was sifted to varying degrees in order to remove some of the bran and to provide flours of a reasonable range of extraction. Complete loaves of breads made from flours of different levels of extraction, water absorption, and baking time were presented to the 72 panelists in order to provide an idea about the range of bread criteria. Also, faulty breads werermade and.presented in order to explain cases such as incomplete puffing and layer separation, burnt surfaces, uneven color distribution, and abnormal texture. Also, bread subsamples of a size similar to that in the actual study were presented to the panelists for evaluation using the score card. Reference samples that presented excellent quality characteristics were included during the training program along with other bread samples for comparison. During the preliminary training program, panelists were allowed to evaluate these samples and ask questions. The esthetic properties of Balady of Balady bread which were addressed to the panelists can be summarized as follows: For bread appearance, the loaf should be of wide diameter and symmetrically round, and evenly distributed golden brown color with some pin points of brown spots, and have a completely formed air pocket that separates the loaf into two layers of nearly equal thickness with the least amount of crumb. For bread texture, the loaf should be soft in texture, slightly elastic and less plastic so that it does not tear very easily, however, it should not be tough, rubbery, nor leathery. Upon mastication, the piece of bread should moisten easily, and be lightly chewy, but not crumbly nor gummy. The loaf should smell nice with no off or burnt flavor. It should taste slightly sweet, not salty, yeasty, doughy, nor floury. After the panelists became familiar with the product and the evaluation procedure, four bread samples per each setting which were selected according to the statistical balanced incomplete block plan # 11.10 of Cochran and Cox (1957) were introduced. Marks on the 10 cm lines were converted into numbers from 0 to 10. Also, a combined score that describes the overall quality of the bread was calculated by adding panelist scores of all bread characteristics. About eleven panelists attended the actual tests regularly. However, five of these volunteers did not show up at some days because of unexpected events. Therefore, 73 data from the six panelists completed all the sensory evaluations were subjected to the balanced incomplete block statistical analysis following the procedure outlined by Gill (1978). The Scanning Electron Microscopy Study Preparation of Dough Samples The procedure described by El-Minyawi (1980) was applied with the exception that no further fixation or dehydration was done after freeze drying dough samples. Dough samples were prepared in duplicates using the farinograph. The freeze-dried, freeze-fractured dough pieces were mounted on aluminum stubs, and sputter coated with a thin layer of gold coat. Different areas of the samples were viewed and examined. Representative micrographs were collected and studied. Preparation of Bread Samples Two subsamples were randomly chosen from each of the seven replicates of the bread baked from the eight flours and were subjected to the ultrastructure evaluation using the SEM. Two different methods were used in the preparation of bread samples. In the first method, no chemicals were used for sample treatment and samples were just freeze dried, fractured, and viewed using the SEM secondary electron detector. The second method was intended to enhance the electron density of the bread specimens in order to improve their viewing images and to use the back- scattered electron (BSE) detector of the SEM. The BSE technique enables processing images based on the topography as well as variation in the electron density of the sample surface. Method #1: Imediately after the baked bread cooled down to room temperature, small thin strips from each loaf representing the upper and lower layers were frozen, then freeze dried and fractured. IRepresentative 74 samples from the top and bottom layers were mounted, and then treated similarly to the mounted dough-strips. Method #2: The freeze dried bread samples (about 8 m3) were fixed in 4% glutaraldehyde solution (0.1 M Sodium phosphate buffer, pH 6.7) for 4 hours. The samples were washed three times with the phosphate buffer (0.1 M, pH 6.7) to remove the excess glutaraldehyde. Samples were dehydrated using a series of acetone-water solutions (25, 50, 75, and 100% acetone). Dehydrated samples were treated with.l% acetyl ferrocene solution (Donated by Mr. H. Ali, Chemistry Dept., Michigan State University) for 8 hours. Samples were washed with acetone several times before replacing the acetone in the sample with ethanol using a series of 33, 50, and 100% ethanol. Then, samples were dried using the Balzers (model CPD010) critical point dryer. Dried samples were then mounted on aluminum stubs and carbon coated. The scanning electron microscope (JEOL JSM-BSC) was used for viewing the specimens. The secondary electron detector was used to process images from all samples, whereas the backscattered electron detector was only used to process images of bread samples prepared using method #2. Different areas of each specimen were viewed and examined at 15 RV and different magnifications. Representative micrographs were collected and studied. Chemical Analyses of Flour and Bread Samples Chemical analyses of flour and bread samples were the same except that bread samples were freeze dried, dry-milled to approximately 0.3 mm mesh, and kept in capped jars at about -20W: until their analyses were carried out. Only flour samples were subjected to the determination of Alkaline water retention capacity, damaged starch, and total pentosans contents, while both flour and bread samples were subjected to all other chemical analyses. All chemicals and solvents used were of an analytical 75 or reagent grade. The active dry yeast was from Food Star (Universal Foods Corporation. Milwaukee, Wisconsin). Alpha-amylase (heat stable enzyme, Sigma I XII-A), pepsin (1:1000, Sigma I P7000), and Pancreatin (Porcine, Grade IV, Sigma I P1750) enzymes from Sigma (Sigma Chemical Company. St. Louis, Missouri) were used. Damaged Starch Data for damaged starch were provided by Dr. J. R. Donelson, SWQL, Wooster, OH. The damaged starch content of wheat flour was determined directly after the milling process. The enzymatic procedure developed by Donelson and Yamazaki (1962) was used. Flour damaged starch content was calculated from the reducing sugars produced by enzymatic hydrolysis of the damaged starch and evaluated as to maltose value (Table 14.01; AOAC 1980) after correction for inherent flour reducing components was calculated from a sample blank. The maltose value is then multiplied by 1.64 as a correction factor that represents the reciprocal of the mean percentage maltose yield from the autoclave hydrolysis of three starch suspensions. Alkaline Water Retention Capacity (AWRC) of Flour Samples The AWRC of the flour was determined by the method of Yamazaki et al (1968) to evaluate soft wheat flours. This procedure was approved on Oct. 8, 1986 by the AACC (AACC 1983, Supplemented Method I 56-10). A 1.0009 flour sample was weighed into a tared 85 x 15mm culture tube. A 5.0 ml 0.1 M sodium bicarbonate solution was added. The tube was capped, and shaken vigorously by hand to get complete suspension of the flour. Tubes were then shaken every 5 min for a total period of 20 minutes. Tubes were then centrifuged using a general laboratory centrifuge (Sorvall, model Glc-l) at 1000 x g for 15 minutes. The tubes were tilted to drain the excess liquid before reweighing. The weight gained was then expressed as a percentage of the flour (on 14% m.b.) or as 9/9 of flour proteins. 76 Total Pentosans of Wheat Flour Samples The method used was that applied by Hashimoto et a1 (1987) which utilized the color reaction of pentoses and the orcinol reagent (Albaum and Umbreit 1947) in measuring pentosan content in baked products. The procedure allows acid-hydrolysis of wheat flour complex carbohydrates followed by removing the glucose by yeast fermentation. The total free pentoses were then measured by a colorimetric reaction with the ferric chloride-orcinol reagent. Pentosan content was calculated by multiplying pentose content by 0.88 as a conversion factor. Moisture Content The AACC method 44-40 (AACC 1983) was used to determine moisture content of flour and bread samples. One gram of the sample was weighed in a predried and.weighed aluminum dish. Samples were dried in a hotpack.#633 vacuum oven at 90°C under 25m Hg vacuum. Protein Content The micro-Kjeldahl procedure of AACC method 46-13 (AACC 1983) was followed to measure the total nitrogen content (N%). Protein content was calculated by multiplying the 8% by the factor 5.7. Crude Fat Content Lipid content of flour and bread samples was determined gravimetrically as crude fat employing the petroleum ether extraction procedure of AACC method 30-25 (AACC 1983). Ash Content The AACC Method 08-01 (AACC 1983) was followed to determine the ash content of flour and bread samples. A two-gram sample was incinerated in a preweighed porcelain ashing dish using a Temco muffle furnace at 575°C until constant weight. 77 Total Dietary Fiber Content The total dietary fiber content of flour and bread samples was determined using the enzymatic gravimetric method of.Asp1et al (1983) with a slight modification of the enzyme system used. The alpha-amylase (heat resistance) was used to solubilize the sample starch, while the proteolytic enzymes, pepsin and pancreatin were used for digestion of sample proteins. The procedure simulates the human digestion process. The undigestible residue was then treated with 78% ethanol to precipitate the soluble dietary fiber. The weight of the total dietary fiber was calculated as moisture, protein, and ash free, then, expressed as percentage of flour on dry basis. Physical Measurements of Balady Bread An objective evaluation of the baked Balady bread samples included measurements of thickness, color, and the texture of the loaf top and bottom layers. Three subsamples each of which represents one-sixth of.a loaf were picked up in random from each replicate and were subjected to the following tests. The average of three measurements represented the mean value for each replicate. Thickness of Balady bread Top and Bottom Layers The thickness of loaf top and bottom layers was measured by a caliper. The thickness of bread layer is expressed in millimeters. Texture of Balady Bread Layers "Puncture Test” The Instron Universal Testing Machine equipped with IEEE- 488 interface (Model 4202, Instron Corp., Canton, Massachusetts) was used. A 5 Kg compression load cell (AS12-13) was attached to the Instron cross- head and a probe of 1/8” (3.1mm) in diameter was hooked to the cell. The cross-head speed was set at 50mm/min. A cork.bore #9 (16.4mm id) was used 78 to cut a disk from the bread layer to be used in the puncture test. The sample was placed over a metal base that had a circular hole lined concentrically with the freely moving probe. The probe was allowed to punch through the sample completely. As the probe penetrated the sample, the force-distance rheogram was recorded on a chart recorder. The height of the peak represents the maximum force (N) required to puncture the sample. Area under the curve (H mm) represents the total work required to punch through the sample. Three subsamples of each of the top and bottom layers of bread from each replicate were used. An average of the three readings represents one replicate. The puncture test was chosen to resemble the action of the tooth on the bread. Peak height and area may represent the force and.work required by the tooth to penetrate the bread. Measurements can be expressed per unit of sample thickness. Force- Distance curve is plotted at crosshead speed 50mm/min; max extension 5 12mm; load range 50% of full scale; recorder time 0.5 minute; and x-axis time - 2. Color of Balady Bread Tep and Bottom Layers Color of the outer surface of the upper and bottom layers of each of the three subsamples of the baked loaves was measured using the Hunter Color Difference Meter Model D25M/L-2 colorimeter (Hunter Associates Lab. , Inc., Reston, Virginia). The instrument was standardized using a calibrated standard white tile (L c 92.35, a - 1.2, and b - 0.5) prior to analysis. Representative samples of constant surface area (the bread subsample had an area of about 25 cmz) were used. The specimen was placed in a transparent cylindrical glass cup and centered on the instrument opening. The extraneous light was avoided by covering the cup and the opening of the instrument with an inverted white can. When values for L, a. and b were recorded, the cup containing the specimen was rotated 90%: 79 and another three readings were noted. The values of the two readings at the two specimen positions were averaged to represent the specimen color. Statistical Designs During the course of this project, several statistical designs were selected, planed, and used to achieve proper accuracy, to assure validation of the tests used for comparisons among treatment means, and.to isolate the effects of nuisance factor(s) that were expected to have some involvement in increasing the experimental error. Most of these designs were chosen in consultation with Dr. J. Gill of the department of Animal Science, Michigan State University. This section presents these designs, their mathematical models, number of replications, and factors (treatments) considered, as well as the restrictions or conditions that demanded the use of a particular design. Complete Randomised Design (CRD) Complete randomized designs were used in the experiments for which no constraints, restrictions, or nuisance factors (such as fluctuation of room temperature or relative humidity) were expected to be involved, and when all of the eight soft winter wheat varieties could be tested altogether in an appropriate number of replications. These experiments included: flour and bread proximate analyses, flour damaged starch determination, and farinograph and all mixograph tests except for mixograph tests at three fixed. water absorptions. Unless otherwise indicated, two replications were made. Tests of expected inherently high experimental error, as was shown by preliminary tests or was known from prior experience, were performed using more than two replicates. Measurements of flour protein, ash, and lipid contents, farinograph and mixograph at baking water absorptions, and, bread protein, TDF, and lipid 80 contents were ran in triplicates, whereas four replicates were’made in the measurements of flour TDF. Runs to be made (total of eight wheat varieties times the number of replications) were assigned random numbers and, thereafter, tests were carried out in that randomized order. The mathematical model for CRD is Y” I p + Wi + 36);“ (Gill 1978) where: Yi is the observation made on replicate j of wheat i, J u a constant; the true mean of the distribution of Y for a population defined by the experimental conditions as a whole, 'W. is the fixed effect of wheat i. W takes values from i I 1 to t I 8 wheat varieties, and E is the residual error. (in Complete Block Design (CBD) This design was used when prior knowledge suggested the involvement of some nuisance factors which could not be eliminated or controlled by practical means. These nuisance factors may be internal to the experimental unit, such as uniformity in size for example, or may be external to the'experimental unit, such as temperature, relative humidity, or time of testing (Gill 1978). It is recommended then to separate the experimental units into uniform groups ”blocks” according to their size or working conditions so that differences within the groups are much smaller than those among groups. The treatment or treatment combinations are then assigned to these groups or blocks. Each treatment or treatment combination will appear once in each group (block or ”replicate”). CBD was used in the measurement of flour AWRC and total pentosan content. The eight wheat flours were evaluated altogether as a group at a time. Four groups ("replicates" or blocks) were carried out. In the AWRC test, the centrifuge capacity was eight tubes which mandated 81 variation in the holding time before centrifuging. Such variation was expected to affect AWRC measurements and presented a restriction on the selection of the statistical design. .Also, during total pentosan determination, it was found that color intensity varied depending on the elapsed time between.development of the color and color measurement. That variation, also, presented.a restriction.on the number of runs that can be carried out at a time. Therefore, the eight wheat flours were tested together in four groups (blocks) of eight runs per group. ‘Wheat varieties were randomized within each block and the four blocks were also carried out in a random order. The mathematical model for CBD with t treatments and r replicates (blocks) is 2.. 5 p + wi + 0’. + E (0111 1978) 1) (ii) where: Yij is the observation made on wheat i of block j, Dj is the random effect of block j (jI 1 to jIr), and E is the residual error. (ii) Balanced Incomplete Block Design (BIBD) The use of a BIBD was necessary for the baking test and bread evaluation. During the preliminary baking tests and evaluation of the baked Balady bread, three restrictions were encountered. First, it was impossible to bake breads from all of the eight flours in one day. Second, panelists' judgement is expected to be impaired when number of samples to be evaluated in one setting is large. Third, conditions such as temperature, relative humidity, and barometric pressure in the baking laboratory were fluctuating to the degree that day- to-day variation was found significant during the preliminary baking tests. Therefore, a BIBD arranged in complete replications (Plan 11.10, p. 573, Cochran and Cox 1957) was recommended by Dr. J. Gill, Department of Animal Science, Michigan state University. Breads from the eight SWW 82 flours were baked and evaluated according to a fourteen day plan, of which two consecutive days, i.e. two incomplete blocks, form a complete replicate, i.e. a complete block, giving a total of seven replicates at the end of the test. The design efficiency was larger than 0.86 (Cochran and Cox 1957). The design was balanced because all blocks were of the same size (four treatments per block) and all pairs of treatments appear in the same block the same number of times (lambda I 3). Under these conditions, pairs of treatment means are compared with the same precision. The mathematical model for the objective measurements made on the Balady bread according to a BIBD of tI8 treatments (wheat varieties), bI14 blocks (days), KI4 treatments per block (four wheat flours are tested per day), and lambda-3 (the number of times any pairs of treatments meets in the same block) is Yi' (U) (Gill 1978) where: Y3] an observation made on bread from wheat i of block j, Bj the random effect of block j (j I 1 to j I b), and 2(U) is the intrablock error. After the calculation of wheat and block sum of squares in the regular manner, wheat means were adjusted to eliminate the effect of blocks on wheat means. The adjusted sum of square of wheats and blocks were calculated according to (Gill 1978). When sensory data were to be analyzed, additional terms were included in the model to represent the main effect of the panelists as another factor (P) and its possible interactions (WP and BP) with wheats and blocks. The model in this case is Yijk ' l‘ * ”i " a]. * Pk * ”mi: * (BP)): * Emu) where: ‘YUk the observation made on bread from wheat i in block j by panelist k, 83 Bj the random effect of block j (j=1 to jI14 blocks), Pk the random effect of panelist k (kIl to kI6 panelists), (WP) and (BP) are the two-way interaction of Wheats x Panelists and Blocks x Panelists; respectively, and, E is the intrablock error. (ijk) Calculations proceeded as in the case of objective measurement, however, additional terms were incorporated to the equations to account for panelist effects (Gill 1987, personal communication). Yates (1940) indicated that types of BIBD in which blocks are arranged in complete replications can be analyzed as if they were CBD and the overall treatment means can be compared without any bias. CBD can be also used to analyze the data of BIBD when block effect proved insignificant (Gill 1978). Therefore, whenever block effect was negligible (P>0.05), blocking was ignored and the data were analyzed according to a CBD of seven replicates (complete blocks). The mathematical models of the CBD are similar to those of BIBD mentioned above, except that adjusted terms are excluded. Split-plot Design (SPD) The back-extrusion test was utilized to evaluate some of the rheological properties of the eight SWW flour-water doughs. Because dough properties are known to be shear rate dependent, the scope of the experiment was extended to study the effect of the back extrusion shear rate on the characteristics of the wheat doughs. The statistical design applied was a split-plot with repeated measurements (Gill 1978, 1986) . The design was selected to assure accurate comparison among shear rates by assigning subsamples from each dough to the three shear rates used in the test. The design helped also to cut down on the rawrmaterials and time needed. Flour-water dough (about 235 9) from each wheat flour was considered the experimental unit "whole 84 plot”, whereas subplots were subdivisions (35 t 3 g each) from these whole plots. Three levels of shear rates (3.14, 6.27, 9.41 sec '1 which correspond to plunger speeds of 10, 20, and 30 mm/min, respectively) were assigned in random and in duplicates to six subdivisions (subplots) from each dough. The whole test was replicated twice. The main factors involved in the design were wheat varieties (eight flours), shear rates (three levels), replications (two replicates), and sub-samples (two subsamples). Subsamples were split over shear rates. _ The mathematical model SPD with repeated measurements (Gill 1978, 1986) has the following form: Yiik - p + wi + RH“. + 3k + ”Si: + Rsmjk + E where: Yin the measured response (i.e. peak load), p the grand mean of the response, Wi the fixed effect of wheat flour-water doughs (iIl to t=8 doughs), RIHJ the random effect of replicates (jIl to rI2 reps.) Sk the fixed effect of shear rate (kIl to mI3 rates), SWH‘ the two-way interaction of wheat x shear rate, RS k the two-way interaction of replicate x shear rate, and, (5” E the residual error. If W x S interaction proved significant, then the comparison between wheat means should be made within each shear rate, and the comparison of means of the three shear rates should be made for each wheat (Gill 1978). Significant interaction indicates that each wheat, i.e. dough made from such wheat, responded differently to different shear rates. In other words, each shear rate produces different response in the dough depending on the flour type from which that dough was made. The analysis of variance (ANOVA) for each particular design was made using the ‘MSTAT statistical software (MSTAT 1985). When the Null hypothesis "Insignificant wheat varietal effect”, H:WVI0 (for all i) was 85 rejected (P<0.05), means of the eight SWW varieties were separated by using the pair-wise comparison method, Tukey's honestly significant difference (HSD) test (Gill 1978) using the MSTAT software (MSTAT 1985). To allow visual judgment of treatment effects, treatment means were graphed using the Graph-statistical Package; Plotit (Eisensmith 1985). Development of the Prediction Equations Mathematical equations that can be used to predict optimum water absorption and mixing time for Balady breadmaking'were developed using the step-wise regression technique of SAS statistical package (SAS 1986) at the Michigan State University Computer Laboratory. Measurements used as predictors included flour data, as well as flour-water dough rheological measurements. Simple correlations between pairs of all measurements were calculated. Multiple correlation between some of those predictors and baking water absorption and mixing time were developed using the following linear regression model: Y I B x . Where, Y is the dependent variable; baking water absorption or mixing time, B is the coefficient vector, x is the matrix of the predictor; independent variables which were selected from chemical, and physical, and rheological measurements. Predictors were included in the model by the step-wise technique depending on their independence and their contribution to the model perfection. Simplest and powerful models, i.e. those having high coefficients of multiple determination; R2,*were selected. RESULTS AND DISCUSSION Milling Data of the Eight Soft Winter Wheat Varieties Because the milling process of wheat grains in addition to wheat varietal and growing condition differences determine composition and quality of the flour produced (MacRitchie 1984), differences among the eight soft winter wheat (SWW) milling will be discussed. Flour yield, extraction rate, and straight grade flour are synonymous to the weight of flour produced from milling of 100 g of wheat grains. Normally, soft wheats have flour yields in the range of 72-79% (Yamazaki and Andrews 1982). Finney et al (1980b) also reported that milling of tempered soft wheats yielded flour in. the range of 71-74%, however, dry' milling increased flour yield to 81-84%. Because Balady bread is traditionally baked in Egypt from flour of high extraction up to 90% (Morad et al 1984), the regular settings of the Miag Multomat mill were modified as outlined in the methods to obtain the highest yield possible. Dry milling data (Figure 3) of the eight soft winter wheat (SWW) varieties were supplied by the SWQL, Wooster, OH. Percentages of bran fraction varied largely among the eight varieties, whereas less variation was noticeable with regard to flour and shorts fractions (Figure 3). Milling Tecumseh produced the lowest amount of shorts and bran fractions and the highest flour yield. However, percentages of extracted flour of the rest of the SWW varieties did not show' much variation among themselves. The higher flour yield of Tecumseh in comparison with yields of other SWW varieties and the small variation in flour yields within those other wheat varieties are in agreement with what had been reported for the straight grade flour yields of these wheat varieties (Everson et al 1988). 86 87 . deem eues must. mmseuuem . :0 .5055003 . 055 5555500 55052 5505 an 5055 oewumuoe es» en Haee assouasz use: es» >s peosooum meeuefiuew usess news“: uuom usmfie esp mo unawuosum msfinuwe sens use .uuuosm uncah .n Oak 3.. ZO_._.O= @8550 . . . . . 0 . h I b > b b D > h D h D D > .00.... 00.00009 .0. O O O O O O O O O O 0.0 O O O a . .fimmm. :eBEso 5.5.2 sceo< >._.w_m<> ._.> =25 I so: I 88 Increasing flour extraction rate to 90\ extraction is expected to affect flour chemical composition and probably its functionality in comparison to the straight grade flour from the same wheat variety. MacRitchie (1984) indicated that the intensity of milling affects flour baking quality as the amount of damaged starch resulted from severe milling will increase flour water absorption and gas producing power. Flour Composition Evaluation of the eight soft winter wheat (SWW) flours of 90% extraction includes the proximate analyses of flour. In addition, damaged starch, pentosans, and flour alkaline water retention capacity (AWRC) are given to relate to the water absorption of the flours. Proximate Analyses of the Eight SWW Flours Proximate analyses of the eight SWW flours milled to 90t extraction are summarized in Table 5. [Analyses of variance which are included in the Appendix showed significant differences (P<0.05) among the eight SWW flours with respect to protein, ash, and lipids (Petroleum ether extract) contents. Total dietary fiber contents did not vary significantly (P>0.05). Comparisons among means or the eight flours were performed using Tukey's BSD test (Gill 1978). Protein contents of the 90% extraction flours.milled from the eight SWW varieties was in a narrow range of 10.71t - 11.68% (d.b.) with an average of 11.21%. Data supplied by the SWQL which are included in the methods for these eight SWW varieties grown at seven locations in Michigan indicated a wide range of 8.6t - 16.8t (d.b.) for whole kernel protein content. That narrow range of protein contents of the milled flours resulted from using selective blends of wheat grains from particular locations for each wheat variety. 89 68233.. B 3:538 :2 £3.33 52138 .38 a. 98 . .cowuoetuxe genus sandstone >5 nec_sceuoe eu.n_. out; o .38. .a so as: 88.: ES»? .32 2 is u .s.m x a u .ceos of 33:33 3 no! 983.2030 .0 3i... 9 .u. gueoctonc: oooe.n a. case goes 9o comue_>on stenceuu 0:» .ansop ...99 neon ow: e.>ex:» >5 cease use as Am9.9xa9 acetoe~_o >9uceu_9_co.m uoc sue teens. else use up peso..ow not e c. aces: e 99.95 99.35 9~.k 99.9» and» 993K Sums 3.9» see: x .9939 3.9 3.9 3.9 3.9 ~—.9 ~9.9 2.9 99.9 .9.9 n 99.9 99¢ N9... 99 Nb; 99< .9.— 2 99... 99 .R.’ 9 95; < ~9.~ 9 99.— cost a .083: N99 ~9.9 99.9 99.9 5.9 «9.9 _.9.9 99.9 9.9 n «9.9 9‘ 9p; 99 Np; < 9~._. 99¢ 3.... 9< 9.... 9 99... 99< 3... 99 -.- coo: a . £2 «96 3.9 -.— 99.9 99.9 95.9 3.- 2.9 .96 c n99 < No.9 ¢ ~9.9 < 59.9 < 99.9 < «9.9 < 99.9 < 99.9— < 5.9 :00: u .099» 2.9 e~.9 3.9 99.9 3.9 3.9 3.9 99.9 .9.m n 99.9 9< 99.: 9 {.9 99 ~p.: 99 3.: 9< 9~.: < 99.: 99 99.9w 9< ~¢.:. see: x .0539... a: dd £9.38» €15.23: 389: 3.3:... 5.6 :338 £32 .53 33:»: 830...; weeps out! Com astute) uses 92. Com 8309.86 999 we 950: “-25 L35: tom use; 05 mo no.3 eeuea 3min: 3.5.8.5 m 39: 9O Flour protein content is both an environmental and heritable traits, but protein quality is heritable only (Pomeranz 1980a,b). All the eight SWW varieties used in this study were grown under the same conditions. Moreover, their grains were blended selectively so that 90% extraction flours of a narrow range of protein content were obtained. Thereby, any differences among these flours in their performance in the breadmaking process might be attributed to the quality of their protein or to other compositional differences. Protein content of wheat grains varies significantly by crop year, wheat class, and growing location (Davis et al 1981). The same report indicated that white SWW varieties in comparison with red SWW varieties, had significantly lower protein contents. Data of protein contents in Table 5 are in agreement with that finding, but were slightly lower than the values reported by Davis et a1 (1981) as a result of flour extraction. Increasing flour extraction increases protein content of the flour. Abu El-Azm (1989) reported protein content of 11.72, 10.34, and 9.70% (d.b.) for 100, 82, and 73% extraction flours milled from the Egyptian soft wheat variety Giza 157. Total dietary fibers (TD!) of the eight SWW flours ranged from 8.57% — 10.30% with an average of 9.36% (Table 5). Data in Table 5 for TDF are in agreement with those of Asp et a1 (1983) as they generally were lower than the reported value for a whole wheat flour (10.3%) and far higher than that of a flour of regular extraction (2.4%). Higher values of TD! were reported by Prosky et a1 (1985) for whole wheat (12.57%) and white wheat (2.76%) flours. A standard error of 0.45 was found among replicates of the eight SWW flours. Asp et al (1983) reported a standard deviation of 0.32% for TDF determinations of 14 samples having an average TDF of 11.32%. Prosky et al (1985) reported from their collaborative study a high coefficient of variation of 9.80% for TDP data of a white wheat flour, whereas that of a 91 whole wheat flour was 5.95%. Those values indicate the inherent error in the determination of TD? of wheat flours. Ash contents was in a narrow range of 1.09%-1.20%. This values are typical to flour of high extraction (Ford and Kingswood 1981). Data in Table 5 were lower than those reported by Cooke (1986) for ash contents of wheat grains of Augusta, Frankenmuth, Hillsdale, and Tecumseh as a result of flour extraction. Again, increasing extraction rate of the flour increases ash content (Abu El-Azm 1989). Ash content of 1.30, 0.95, and 0.60% (d.b.); respectively, was reported for 100, 82, and 73% extraction flours milled from the Egyptian soft wheat variety Giza 157 (Abu El-Azm 1989). Lipid contents of the flours ranged from 1.69% for Adena to 2.02% for Auburn, with an average of 1.84%. The inclusion of large amounts of bran and shorts fractions into wheat flours to make up for the 90% extraction is expected to increase flour lipids. Wheat germ, which is rich in lipids, makes up 3% of wheat kernel and about 85% of the germ goes to shorts fraction upon milling (Lai et al 1989). Abu El-Azm (1989) reported that increasing flour extraction of the Egyptian soft wheat Giza 157 from 73% to 100% increased flour fat content from 0.71% to 1.69% (d.b.). Total carbohydrate contents (excluding TDF) of the eight SWW flours ranged from 75.7% to 77.2% with an average of 76.5% (Table 5). Flour total carbohydrate content correlated negatively with flour contents of TDF (:3 -O.86, P<0.01). Damaged Starch, AWRC, and Pentosan Content Data of the eight SWW flours for damaged starch, alkaline water retention capacity (AWRC), and pentosans are summarized in Table 6. Analyses of variance included in the.Appendix showed significant variation 92 .2 5350?! pose... .. coon goes .6 7...... 5.3.5.. eta—xi... o... .88. :8. 33 8.. .38.... B :32.» see as 39.9... accent... 3.5.0.25... an: o... .030. as... 3.. B 9032...» so. a c. scoot u .3 £332. .53 5:30 .935 Com 2... mo c6338.. ._. .3 3 90:99.... 0...... :3 an... a... .5 note... 9092.... n .50... 3.. 33.5.3 3 to... 32:23.... .6 .385: e K... s... E... .3... co... .m... o... B... a... .. 8.... < ~o.~ < 3.. < 2.... < .3... < 3,... < ..~.n .. 8.». < 2.... E... a £5.35. 8... ~.... 8... 3... ~..... 3... 2... ~.... 6.. .. 8... u 8.. 9. 3.. u n... u on... u. 3.. u 3.. < n... u n... E... 538.. 2. .95.. 8... n... .3... ..~.~ ..~... mm... 8... _ o... a... .. 3... < 8.3 e. 8...... . .3... .. no.8 .. 8.3 < R... .. R... < 9...... S... 6.... a... u .95. 3... o... o... 3... 3... ~..... ~..... .~... 5.... ~ 8... < o... u... R... u... on... u... .n... u. ...... u ~.... 9. on... u... 3... .5... u {.83. ... .2 d... .85... finesse... 38...... 3.8:... .61.... :83... £32. .5.... 33.3... 82...... 3...... 3...... to. 330...; .35 was Com 28.. .92... .35.. to. 2.... .5 .. 23:8 58...... .z. 5...... 8.23... .3... 8...... £33.. 63...... 9 39¢» 93 (P<0.05) among flours with respect to damaged starch and AWRC. No significant differences (P>0.05) were found among pentosan values of the eight flours. Damaged starch data which were supplied by the SWQL, Wooster, OH showed (Table 6) small but significant (P<0.0S) variations among the eight flours. Tecumseh flour had a significantly higher (P<0.05) damaged starch content than that of Charmany or Caldwell flour. In addition, Caldwell flour had also lower (P<0.05) damaged starch content than that of Auburn. Damaged starch contents of the eight SWW flours ranged from 4.12 to 4.59% (14% m.b.). These values are at the upper limit of the range (2.6-4.3$) reported by Finney et al (1988) for flours milled from soft wheats. Damaged starch which is produced during milling, affects water absorption capacity of the flour (MacRitchie 1984). It also has some influence on dough properties, production of fermentable sugars, loaf volume and crumb texture (Pomeranz 1968). The»modification of the regular milling procedure and the extra milling steps made to increase flour extraction up to 90% may be accounted for additional starch damage. Ford and Kingswood (1981) found that increasing feed rate during milling increased the amounts of flour released and damaged starch. 'They recommended that the role speed of the mill be increased to reduce the amount of damaged starch when milling at high feed rate. Alkaline water retention capacity (AWRC) of the flour showed significant variations among the eight SWW varieties, both on 14s m.b. and on g/g protein basis (Table 6). AWRC was expressed per gram protein in order to eliminate variation related to the small differences in flour protein contents among varieties. Thereby, differences in AWRC g/g protein among the eight flours can be related to the hydration capacity of a unit of flour protein and the other flour constituents. Hillsdale and Augusta flours had significant lower (P<0.0S) AWRC‘ values than all other 94 flours except Frankenmuth (Table 6). AWRC of whole wheat flours milled from four wheat classes was found to be in the range 53.8 - 67.8t on 145 m.b. (Abboud et al 1985). When AWRC values were expressed as g/g of flour proteins (Table 6), Auburn and Frankenmuth flours had similar values of AWRC g/g protein which were higher (P<0.05) than those of the other flours with the exception that the difference between Frankenmuth and Charmany flours was not significant (P>0.05). Differences among the other flours were not significant. Flour AWRC g/g protein was found to be in positive correlation (r-O.70, P<0.0S) with flour content of TDF. Wheat flour imbibes water at any pH level, but hydration of flour proteins is limited at moderate alkaline pas (Yamazaki 1953). Major constituents which effect water hydration capacity of a given flour are proteins, starch, and pentosans. Starch in its aqueous suspensions absorbs water up to one-third of its weight and swells up to St of its volume (Hoseney 1986). Starch-water uptake and swelling are greater for damaged starch and partially damaged starch granules than for intact ones (Pomeranz 1968). MacRitchie (1984) indicated that damaged starch produced during milling affects water absorption capacity of the flour. Abu El-Azm (1989) found that water retention capacity increased as flour rate of extraction was increased. Pentosan contents of the eight SWW flours (Table 6) was in the range of 2.92 to 3.44t with an average of 3.25%. A range of 1.94-3.00% (d.b.) was reported for total pentosan content of whole grains of different wheat classes (Abboud et a1 1985). A significant positive simple correlation coefficient (r I 0.71, P<0.05) was found between flour contents of TDF and pentosans. The correlation may be explained by the fact that pentosans are constituents of wheat dietary fibers (Wisker et a1 1985). Although pentosans constitute a small percentage of the flour, they have the greatest capacity to absorb‘water (Bushuk 1966). This capacity is related to their unique structure (Wisker et al 1985). 95 Rheological Study The rheological properties of the flour-water doughs of the eight SWW varieties were studied using the conventional techniques and the beck extrusion technique. 'The conventional recording dough mixers; the farinograph and. mixograph. were 'utilized. to study dough rheological properties at the water absorptions conventionally used by the standard AACC procedures (AACC 1983) and at the water absorption levels used in the Balady bread baking tests. Measurements of Dough Properties Using Conventional Techniques Farinograph test using the standard AACC procedure: The AACC constant dough weight procedure 54-218 (AACC 1983) was used. In this procedure, the dough maximum consistency is centered at the 500 B.U. line of the farinogram trace. .Measurements taken of the farinograms (Figure 4) of the SWW doughs are summarized in Table 7. Analyses of variance included in the Appendix showed small but significant variations (P<0.05) in farinograph absorption, stability, MTI, and break down time were detectable among the eight SWW flours, whereas differences among dough peak time and arrival times were not significant. Farinograph absorption (PA) is the»amount of water required to center the maximum consistency of the flour-water dough on the 500 8.0. line of the farinograph trace. PA of the eight SWW flours was found in a narrow range of 54.3t to 56.5t (14t m.b.). Tecumseh, Hillsdale and Adena had significantly (P<0.05) lower PA than Caldwell and Charmany. Tecumseh had significantly (P<0.05) lower water absorption than all other flours except Adena and Hillsdale. PA for a particular flour depends, among other factors, on wheat class and percentage of flour extraction. PA of 50.5t and 58.8t were reported for 70‘ extraction flours milled from the two Egyptian wheat - Ell/[Iii], i/léll”.- III I W__—. - ::-:-: 777,, _ gihl’ ”ll - H li4?:::::§:35::::::::: -___-.‘- “r“ \\\\i\'\\i‘\'\i\\'i\l\ \M\\\\\\ \“\\\:\ \ \\\\\\\\\\\ \\\\\\ \\\_ _.__;_ \\x.\\\\\._ \_\\\_\_\\\\ :—————'————————_—- E _._AUGUS-A..,___ :3_:_____________——'—:—: HILLSDALE“ CONS I STEBICV (Brabender units) MIXING TIHE(I1D) Pig. 4. Farinograms (AACC procedure) of the eight soft winter wheat flour-water doughs. $97 .8... :8. .8. 8.. .323. .5 £8... .2. .. 8...... 2.28.... 3.88:8: .8 o... touuo. use. as. 50 nose..o. so. o c. «coo: .uoueu..not or. we ouoeo>e oz. a. coo: seem a .ueegu on. co oc.. .0.0 000 oz. .e co.ooc.... oz. toucou o. nouns no: noun: e P.. —.0 0.0 0.0 5.0 0.0 5.0 5.0 .0.0 0.0 0 0.0 000 ~.n 000 0.0 0 ..w 00 0.~ 00 0.0 < 0.0. 000 5.0 coo: c_l .osmh c300 xooen «.0. 0.— 0.0 0.0. 5.5 ..5 0.. 0.0 .0.m 0.0 00 0.00 00< 0.95 00 0.00 < 0.~0. 0< 0.00 00 0.00 0 0..~ 00 0.00 coo: .:.0 .oucoeo.05 0cmxm: 0.0 ..0 ~.0 «.0 0.0 ..0 0.0 0.0 .0.0 ~.0 < 0.~ < 0.. < 0.. < 0.. < 0.. < 0.. < 0.~ < 0.. coo: cm: .oemh soon 9.. 0.0 0.0 0.0 0.0 0.. ~.0 0.0 .0.0 0.0 0 0.0 00 0.~ 00 0.~ u 0.. 00 ..~ 00 5.~ < 0.0 00 0.~ coo: c_6 .05.» >u_._nouw ~.. 0.0 5.0 0.0 0.0 0.0 0.0 0.. .0.0 0.0 0 5.0 0 ..n 0 0.0 0 0.N 0 «.0 0 5.0 < 0.0 0 0.0 coo: c.E .oE.» ocaueoao0 ..0 ..0 ..0 «.0 0.0 ..0 ..0 0.0 .0.m ~.0 < ... < ~.- < 0.. < F.. < 0.. < 0.. < 0.. < 0.. coo: cme .oE.» .o>_ee< —.0 0.0 —~.0 9.0 0.0 0.0 0.0 0.0 .0.0 ~.0 u 0.00 0: 0.00 0< 0.00 00 0.00 < 0.00 < 0.00 0: 5.00 00 ~.00 ncoo: A.n.i Nepu u..on< cone: . N.” iggh Sui-0:50 lugg< 9.80. d m: 5050 ddgdau E§< §< Duszuu( momuo..e> «nos: o..g: mo.uo..o> .ooca toe no..o.eo> woos: noun.) upon use.m or. .o noeanouoga ou<< neoncoum. azoooo .o.oa-.so.. oz. .0 cause gno.ooc..eu 5 wan<5 98 varieties Baladi and Hindi (Refai et a1 1962). More recently, Abu El-Azm (1989) reported higher PA for flours of 82§ and 73% extractions milled from,the Egyptian soft wheat variety Giza 157. Mousa et al (1979) reported PA of 67.3% and 63.6% for 90$ extraction flours milled from two HRS and HRW varieties. El-Minyawi and Zabik (1981) reported PA of 58.7% for a 74.5% extraction HRW wheat flour. Flour water absorption is related to flour contents of intact and damaged starch, protein, and pentosans. These constituents absorb water up to 0.44, 2, 2.2, and 15 g/g of their weight, respectively (Bushuk 1966). The 90$ extraction of the eight SWW flours is expected to increase their water absorption as they contain considerable amounts of shorts and bran and thereby large amounts of pentosans in comparison to similar flour of straight grade. Bran and shorts have high amounts of neutral detergent fibers (Yamazaki and Andrews 1982) which have high water absorption capacity. Tecumseh when milled, required the least amount of fine bran and shorts to make final extraction of the flour 903 in comparison to other varieties. This might explain its low' water absorption. Arrival and peak times of the eight SWW doughs showed no significant difference (P>0.05) among means of the eight SWW doughs (Table 7). Arrival times were in a narrow range of 1.0-1.5 min, whereas peak times were in the range of 1.5-2.6 min. Flour can be classified according to its dough development (peak time) time to short, medium, or long (D'Appolonia and Kunerth 1984). Data in Table 7 indicate that the eight flours are of short dough development time, a characteristic of soft wheat flours. Short peak times of 0.9 and 1.6 min were reported for 70% extraction flours milled from the two Egyptian wheat varieties Baladi and Hindi (Refai et al 1962). Similar values of 1.5 and 1.0 min were reported by Abu El-Azm (1989) for peak times of flours of 82% and 73% extractions milled from the Egyptian soft wheat variety Giza 157. Longer peak times of 5.0 and 4.5 min were reported for 90% extraction flours milled from two 99 HRS and HRW varieties (Housa et al 1979). El-Minyawi and Zabik (1981) reported 3.6 min peak time for a 74.5% extraction HRW wheat flour. Dough departure times of eight SWW flours were found in the range of 2.6 - 9.3 min (Table 7). Auburn dough had the longest departure time (P<0.05). Differences among other flours with respect to dough departure time were not significant (P>0.05). Dough stability is defined as the time difference between arrival time and departure time (AACC 1983). Auburn dough showed the longest stability (P<0.0S). In addition, Tecumseh doughs were of longer stability than Hillsdale dough (P<0.05). Other comparisons among varieties (Table 7) with respect to dough stability did not indicate significant difference (P>0.05). Flours can be classified according to their dough stability into short or long. Soft wheat flours are usually of short stability in comparison with flours of hard wheats (D'Appolonia and Kunerth 1984). Dough stability of 1.50 and 1.75 min were reported by Abu El-Azm (1989) for flours of 82% and 73% extractions milled from the Egyptian soft wheat variety Giza 157. Longer dough stability of 10.0 and 7.5 min were reported for 90$ extraction flours milled from two HRS and HRW varieties (Mousa et al 1979). Mixing tolerance index (MTI) is the difference in B.U. from the top of the curve at the peak to the top of the curve at 5 min after the peak. The higher the MTI value the faster is the break down of the dough after reaching its maximum consistency. Break down time is another farinograph measurement that has been also used as an indicator for dough stability and tolerance to mechanical degradation of dough structure as a result of over mixing. A dough of long stability, low'HTI, and long break down time can withstand large variations in the process of breadmaking. Significant variations were found among varieties with respect to “TI and break down time. Auburn dough had a significantly lower MTI value than all doughs from other varieties except Tecumseh. Adso, Tecumseh lOO dough had a significantly lower HTI value than those of Hillsdale and Charmany. Break.down time, also, showed similar trend. Easter break down was noticed for Hillsdale and Charmany doughs in comparison with ‘those of Tecumseh and Auburn doughs. Other comparisons showed a slight variation. Data in Table 7 for farinograph MTI of the eight SWW doughs were within the range reported for wheat flours that had been used in making Balady bread. El-Minyawi and Zabik (1981) reported a “TI value of 33 B.U. for a 74.5‘ extraction HRW wheat flour. A slightly higher value was reported for a flour of 72‘ extraction which was imported to Egypt for baking Balady bread (named et al 1973). Higher values of 150 and 140 B.U. were reported by Abu El-Azm (1989) for flours of 82% and 73% extractions milled from the Egyptian soft wheat variety Giza 157. Iixograph test using the standard AACC procedure: The AACC procedure 54-41 (AACC 1983) was applied using a recording mixograph of 35 g mixing bowl. The water absorption level for each of the eight SWW flours were those recommended by Dr. P. Finney after inspection of mixograms made at variable water absorption levels (Finney 1985; personal communication). These mixograms were made using a recording mixograph of 10 g mixing bowl of the Soft Wheat Quality Lab., Wooster, on under the directions of Dr. Finney. Dough water absorption ranged form SS.6$ to 59.5t on 14% moisture basis (m.b.) with the absorption of Hillsdale and Augusta being at the lower end of the range whereas that of Adena being at the upper end. Measurements taken of the mixograph traces (Figure 5) which were made using a 35 g bowl mixograph are summarized in Table 8. Analyses of variance which are included in the Appendix indicated that differences among the eight wheat flours were significant (P<0.05) for all mixograph measurements except peak height. Peak time for the doughs of the eight SWW flours ranged from 1.4 to 3.5 min. Auburn dough had significantly longer peak time than those of other doughs except those of Tecumseh and Frankenmuth. Charmany and 101 3 ll'til II '\\1[i\\ l IV. I I In I“ 1C I I / I I I I I I I j I, 'l I I I I I i I I I I I , I I I / ADERA I HIHHHIHHHH \ \\\'\\\l\\j ‘.'\\\\.\‘.\\\\\\\' \\\\\\ I 7 I liill' |l|9|l|9l| HILLSDALE eight soft 'rrcunssu 7L -)llilv(llllal mmxsuuu'rn f- ///’/«'/III I ‘I: ill! ggl lil ll (min) A If .I I .’ I :/ I lllll 3H AUGUSTA: ; I : 1 I I 7 '1 :1.»ij / I . Ira: “llcwl ’H’l/r j... \\‘.\~ '1 III I! lilll'lllil \ (AACC procedure) of the I l I / ‘\\ -'/ ‘/t'///I//// HHHIIIII “\‘~\\\\‘\‘\fi. MIXING TIME .'/. / 'l \ i)!!! 3 d I I ‘ I / winter wheat flour-water doughs. '19. 5 . 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".8; ~.o a... ~.o .6 n6 a... ~.o «.o ~.° .o.m 2 o.~ 3 n.~ a n.~ u i. u o; a n.~ < n.n 8 ~.~ So: 5... .2: an: 0.3 can can n.nn Mon «.8 min 9% n 82908.. 3:5 .md $9.32 535%.: 389.. 283:: 5.5 .3338 £33 .83 33.32 320...; «3.5 325 8mu0m50> nabs 00¢ 2.30....) :25 53:5 Com 23m 05 no .3339... uu<< Egumv 2.93 53.3-5.8: 2: no .33 £298.; 0 36¢.— 103 Hillsdale doughs had similar peak times that were significantly shorter than those of other doughs except that of Adena. A value of 3.7 min was reported by El-Minyawi and Zabik (1981) for peak time of HRW wheat flour of 74‘ extraction and 58.7t absorption. Peak height ranged from 3.3 to 4.0 MU (Table 8). Soft wheat flours produce mixograms of less peak height than those of flours from hard wheats. A value of 6.8 min was reported for mixogram peak height by El- ninyawi and Zabik (1981) for a HRW wheat flour of 74t extraction. No significant difference (P>0.05) was found among the eight doughs with respect to peak height. Curve height after 8 min of mixing showed significant difference among the eight doughs. Height at 8 min of mixing, when compared with height at the peak, may indicate tolerance of dough to mixing. Hillsdale dough had the lowest 8-min height of any of the doughs except that of Frankenmuth. On the other hand, Tecumseh dough showed a high value for 8- min height which was significantly (P<0.0S) higher than those of other doughs except for that of Auburn. Comparison among means of Auburn, Adena, Augusta, Caldwell, and Charmany doughs showed no significant difference (P>0.05). Doughs of Tecumseh and Auburn had slower break down in comparison with those of Hillsdale and Frankenmuth. The slower break down of Auburn and Tecumseh doughs in comparison to that of Hillsdale was concluded earlier from the farinograph study. Area under the curve showed few significant differences (P>0.05) among mixogram areas of the SW varieties (Table 8). Hillsdale dough showed significantly (P<0.05) smaller area under curve than those of Tecumseh, Adena, and Charmany. This indicates less work was required for mixing of Hillsdale dough than those needed by doughs of the other varieties. Values of mixogram areas in Table 8 are typical for soft wheat flours. El-Hinyawi and Zabik (1981) reported a value of 81.86 cm3 for mixogram area of a HRW wheat flour of 74.5t extraction and of 58.7t absorption. 104 Dough stability is the length of the line drown on thermixogram curve at the center of the peak and parallel to the base line. The dough stability values had the range 3.2-7.6>min (Table 8). Tecumseh and Auburn doughs showed similar stability that was significantly higher (P<0.0S) than those of other doughs. Differences in mixogram stability among means of Hillsdale, Adena, and Charmany or among means of Caldwell, Frankenmuth, and Augusta doughs were not significant (P>0.05) . However, mixogram stability values of Hillsdale, Adena, and Charmany doughs were significantly (P<0.0S) smaller than those of doughs of other varieties except Augusta. It can be concluded that Tecumseh and Auburn doughs required longer mixing time and were relatively stronger and more stable to mixing beyond their peak time. In contrast, Hillsdale dough had shorter mixing time and was weaker and of less stability than other doughs. Because the eight SWW flours had a narrow range of protein contents (Table 5), differences in their mixograph measurements can be related to the differences of the inherited protein quality among the eight varieties (Finney 1989). Finney and Shogren (1972) discussed the relationship between dough handling properties and mixing requirements (using the standard mixograph procedure). Dough of short mixing time (1.5 min) is more likely to be less stable, less elastic, and more extensible than another one of longer mixing time. They also indicated that dough extensibility decreases as dough mixing time increases, whereas stability, elasticity, and mixing tolerance increases. But, as mixing time become far longer (>4-5 min) the dough becomes ”bucky" as the appropriate degree of elasticity and extensibility disappears. Kunerth and D'Appolonia (1985) reported typical mixograms of flours from different wheat classes (HRS, HRW, SWW, SRW, and durum). Those mixograms were made at water absorptions optimized by the farinograph. The mixogram of SAW, in comparison with that of SWW, showed a lower peak height, a shorter mixing time, and a slower rate of 105 dough break down after reaching the peak (as was shown by curve height at the end of mixing). Comparison between rheological measurements made using the two standard farinograph and mixograph procedures: Water absorption measured by the standard farinograph procedure was in a narrower range (S4.3\-56.5t, Table 7) in comparison to that measured by the standard mixograph procedure (55.6-59.5‘, Table 8). Consistently, Farinograph absorption was lower than that of the mixograph for all the eight flours. Miller et al (1956) indicated that the farinograph absorption is highly correlated with flour strength and protein content. Miller et al (1956) studied the correlation between farinograph, mixograph, sedimentation, and baking tests made on hard red winter wheat flours used in pan bread production. They mentioned that farinograph and mixograph supplied similar types of information, however, both apply different mixing action (Pomeranz 1987). Peak time as measured by the farinograph showed no significant difference (P>0.05) among the eight flours, however, differences in peak time as measured by the mixograph were significant (P<0.0S). Both instruments showed that doughs of Tecumseh and Auburn were of longer mixing time, and those of Hillsdale and Charmany were of shorter mixing time relative to other doughs. Miller et al (1956) showed that both the farinograph and mixograph mixing time to correlate well with baking mixing time of pan bread, but the mixograph mixing time correlation was stronger. However, both mixing time of the farinograph and mixograph were poorly correlated. In the farinograph procedure, dough consistency (peak.height) is kept constant (by centering the curve at the 500 8.0. line) by adjusting the amount of added water, whereas in the~mixograph procedure dough is allowed to show its actual strength. Nevertheless, the eight doughs showed similar dough strength as was indicated by insignificant difference 106 (P>0.05) in dough height among varieties. Pomeranz (1987) pointed out to the effect of fermentation period on dough consistency. By the end of fermentation some doughs become weaker (slacker) whereas others become stronger (tighter) than what they were at the end of mixing. That was encountered during dough. manipulation through out the baking test. Therefore, baking absorption and mixing time were adjusted for each dough to achieve better performance. fleasurenents of Dough Properties Using Unconventional Techniques Farinograph study at balady bread baking absorptions: In this study, the farinograph was utilized to evaluate the rheological properties of the eight SWW flour—water doughs at the water absorption levels which have been optimized for making Balady breads. The intention during the determination of Balady baking absorption, using a 400 g mixograph, was focused on increasing flour absorption to the maximum possible to get a dough of reasonable handling properties and well developed gluten. Such dough should also be able to withstand the bread making process until successful baked bread is obtained. Faridi and Rubenthaler (1983b, 1984) have used a 200 B.U. line constant dough consistency to simulate Balady bread baking absorption. These researchers chose to maximize water absorption for optimum Balady bread dough handling characteristics using the farinograph and then determined the rheological properties of these doughs using the mixograph (Faridi and Rubenthaler 1983b). In the conventional standard farinograph procedure which has been used previously, all measurements were made on the farinogram for which dough maximum consistency was kept constant by centering the curve on the 500 3.0. line (AACC 1983). In this study, the consistency of the dough which was indicated by the peak height of the curve had the freedom to vary. After obtaining the farinograms, a horizontal line was drawn at the point of dough maximum consistency. Then, measurements were made as if that‘line were the 500 8.0. line usually used in the conventional method. 107' This might enable understanding of dough properties at the water absorption levels used in the Balady bread baking study. Measurements made of these farinograms (Figure 6) are summarized in Table 9. Analyses of variance of these measurements which are included Appendix established significant variation (P<0.0S) among means of the eight SWW varieties with respect to dough arrival time, departure time, stability, peak time, peak height, and height at 10 min. Arrival time values for the eight SWW flour-water doughs mixed at Balady bread baking absorptions (Table 9) showed an extended variation (0.644.8 min) among varieties and followed the same trend shown earlier when the standard AACC method was used (Table 7). Tecumseh and Auburn doughs had similar arrival time that was higher (P<0.05) than that of doughs made from the other varieties. Doughs of Hillsdale and Frankenmuth had similar values for arrival time which were lower (P<0.0S) than any of the other doughs except that of Adena. Differences among means of Caldwell, Augusta, and Charmany doughs and among those of Augusta, Charmany, and Adena doughs were not significant (P>0.05). Departure times of Auburn and Tecumseh doughs were similar and were longer than those of other doughs. On the other hand, Hillsdale dough had the shortest (P<0.05) departure time. Significant differences (P<0.05) for departure time for dough from the eight SWW flours were in descending time: Auburn =- Tecumseh > Adena :3 Caldwell = Charmany 8 Augusta > Frankenmuth > Hillsdale. Dough stability values of Tecumseh and Auburn doughs were similar (P>0.05) and were greater than (P<0.0S) those of the other doughs. In contrast, Hillsdale dough showed lower stability (P<0.0S) than other doughs excluding those'made with Adena and Augusta flours. Differences in dough stability among Caldwell, Charmany, Frankenmuth, Adena, and Augusta doughs were not significant (P>0.05). The poor stability of Hillsdale dough in comparison to those of Tecumseh, Frankenmuth, and Augusta can be explained by the (Brabender- uni t5) CONS I STENCY W \ j X ‘r' + \ \\_lLL‘ k4 .\_ \ \ \ Y _ \ \‘ \ \ \ , \ ‘ ‘ \ \ \ . \ \ 3 ‘ §< ‘ . ._L . . 3 x ’ \ ‘ \ \ ~., \ \ \._\ ‘ \ i L . ~\ \\\ k \ ( \\ \\ .. \\ ‘ \‘r ‘ \ \ ' V ~ ‘ \ \ \ ‘ \ ‘ \ ~ \ ‘ \ \_L \ \ \ \ ‘ \ fl ‘\ \‘ \\ \‘ \ \ . \ - \ ‘ \ ~ \ x -“\——Vv \'. k \ \ 3 \\ \ \\ \ \\ \ \ \\AA-lis . \ \ ‘ \ \ L \ \ \ a \ \ \ > \W—\i\\ \ \\ \\ x \\ x \ K \6 \ ‘ \ \ \ \ \ ‘ ‘ ‘ \ ‘ ‘0‘ \ \‘—\_¥ . 0‘ o a H Q I! o h a O n 0‘ n n v to o h I .-.-vo MIXING TIME (min) Fig.6 . Fa-rinograns of the eight soft winter wheat flour- water doughs made at baking water absorption levels. 1139 .u_mon otoum_os u .n.e “mucosa >oe.en we co_ustenecn see one: co_untomne tea-s eo u.e>e. new age ones» .5950. ..moo anon on: a.>sx:» so cross as: as .mo.ovao ucotoee_o >.uceu_»mceme a sec can guess. uses ecu >5 peso..ow not s cm aces: .aousu_.noc soggy we oesto>e as» a. can: zoom 0 n .t m a T p o o a.» n 9 new. a in u 8... a 2n ‘ on». u 8~ u m3 a 2... is. .3... .5... 2 3 fit... o m n N o n a n 66 ~ g 8~ u 3». m .8... < in a 8n a .8... 2 an 9 mnn 50.. 5.. .232. so: ~.o .2. n6 ~.o ~.o to ~.o to 4...... to < o6 a m.~ 8 o.~ u o; u ~.n a a; < n6 8 9n 5...: 5.. .2: an: o... a; o... to m... .3 ~._ 9. 6.... .3 < a.» a he 8 n.n u n.~ a .5 . ~.m < he 8 .3 c3: 5.. 523.3 a... a; m... n... .2. «a n; m6 .9.» «a < 3. u n.n . in a o.~ a as a .2 < 3: a 9m So: 5... .2: 23.33 ~.o to ~.o to n... to ~a a... 5.... to < m... o to 8 o; a o... 8 E a ~.~ < a... 8 ~.. 5...: E... is: if: no 8 3 on 3 no 3 8 n.n... a: .x 8.580.: is... .w.m £0300.— zuiuoxcok. luau-03¢ odaezmx Ego-U 30.6.00 E§< g Ouameuut smuflmhfl> 0005 Hum-s eo_u0_ue> uses: use co_unuomb< acumen posse >oeds¢ us pex_x «canoe touex-t:o.u 0:» .0 sense gnesoocmceu o man0.05) and was longer than (P<0.05) any of those of the other doughs. Caldwell dough had shorter peak time (P<0.05) than that of Tecumseh or Auburn, but it was longer (P<0.0S) than those of the rest of doughs. In contrast, Hillsdale dough showed the shortest peak time (P<0.0S) among the eight doughs. In addition, peak time of Frankenmuth dough was also shorter (P<0.0S) than those of Caldwell, and Charmany. Differences in peak time among Charmany, Adena, and Augusta doughs were not significant (P>0.05). Peak height of the eight doughs ranged from 282 B.U. for Tecumseh to 374 B.U. for Hillsdale. The higher the peak height, the dryer and more viscous is the dough. Peak heights of doughs from seven varieties differed significantly (P<0.0S) and can be arranged in descending order as follows: Hillsdale > Charmany > Frankenmuth > Adena > Augusta > Caldwell > Tecumseh. The peak height of Auburn dough ranked between those of Tecumseh and Caldwell and did not vary significantly (P>0.05) from either. A relatively stronger dough was made from the Hillsdale flour when its water absorption was reduced relative to those selected as optimum for other flours so that successful Balady bread could be baked from the flour of Hillsdale by reducing its stickiness. Finney et al (l980b) reported that slight reduction of the amount of water and mixing time used in preparing Balady bread from flours of high levels of field sprouting 111 helped in reducing dough stickiness and enabled baking of acceptable Balady bread from these flours. Height at 10 min ranged form 280 to 310 B.U. for the eight doughs. Charmany dough had the highest value (P<0.0S) among all doughs. Differences in curve height at 10 min of mixing for Adena, Frankenmuth, and Hillsdale doughs were not significant (P>0.05). Also, no significant difference in curve height at 10 min (P>0.05) was found among Caldwell, Augusta, Auburn, and Tecumseh doughs, however, any dough from this group had significantly lower (P<0.05) curve height than those of the previous group. It can be concluded from this farinograph study at Balady baking absorption that Tecumseh and Auburn doughs required relatively longer mixing time to reach maximum dough consistency (peak of the curve), and they were relatively the most stable and tolerant to mixing beyond the peak. On the other hand, Hillsdale and Frankenmuth followed by Augusta and Adena doughs were of relatively shorter arrival time, dough development (peak) time, and departure time. In addition, Hillsdale, Augusta and Adena doughs possessed shorter stability and broke down much faster. The simple correlation coefficients between pairs of the farinograph measurements made on the SWW flour-water doughs at Balady baking absorption are shown in Table 44 in the Appendix. Farinograph arrival time correlated significantly (P<0.00l) and positively with Peak time (r80.95, n=24), stability (r20.84, n824), and departure time (r=O.95, n-24), but it correlated (P<0.00l) negatively with height at 10 min (r--O.65, n824), and peak height (rs-0.81, n-24). Parinogram peak height showed highly significant (P<0.00l) negative correlation with stability (r--O.73, n=24), departure time (rs-0.80, n=24), and peak time (rs-0.85, nt24), however, peak height was positively (P<0.00l) correlated with curve height at 10 min (rsO.88, n=24). 112 Comparison of the rheological measurements of the farinograms made at the standard AACC absorption (Table 7) with those»made at Balady baking absorption (Table 9) showed that as water absorption was increased, arrival time, peak.time, departure time and stability increased except for Adena, Hillsdale, and Frankenmuth. Their arrival time were shorter. Hillsdale peak time and departure time were almost the same. In both studies, Hillsdale dough broke down faster than those of Tecumseh and Auburn. Ilixograph study at balady bread baking absorption: The water absorption used for each flour was that determined by the Balady baking test. The 35 g bowl mixograph was used to evaluate the flour-water dough rheological properties. Measurements taken of these mixograms (Figure 7) are summarized in Table 10. Analyses of variance which are included in the Appendix indicated significant variation (P<0.0S) among the eight varieties with regard to peak time, peak height, height at 8 min, and area under curve. Peak time of Tecumseh and Auburn doughs was similar (P>0.05) and was significantly longer (P<0.0S) than those of other doughs. Caldwell dough had longer (P<0.05) peak time than those of Charmany and Frankenmuth; while Hillsdale dough had the shortest (P<0.0S) peak time of all doughs. Differences in peak time among Adena, Augusta, Charmany, and Frankenmuth doughs were not significant (P>0.05). Peak height showed also some significant variations among doughs of the eight flours. .Augusta dough‘was significantly (P<0.05) stronger, i.e. having higher value for peak height, than Frankenmuth, Tecumseh, and Auburn doughs. Charmany dough was also stronger (P<0.05) than Tecumseh and Auburn doughs. However, difference in peak height among Augusta, Charmany, Adena, and Hillsdale doughs or among those of Frankenmuth, Tecumseh, and Auburn were not significant (P>0.05). 113 l! .9 11 E 3 S n it i. D X AUGUST): 1” ' I i " I I f «It " Z I" I 0 . 7‘ . H -—-——__= . -. ill //’/.I///I/////I///,I.///:'//// I ‘mnmLIIIIIIIIII ' I I II {H HUI" “acumen . "i. HIXIN. TIME (min) Pig. 75.. flixograns of the eight soft winter wheat flour- water doughs made at baking water absorption levels. 1J14 .a_esn otsue_oe u .b.s "unseen xoedeo eo co_uetsnoan toe on»: co_untoene tones yo a.o>o. new use ones» ...:.: o. u o.uon .dseo some: snstooxmx u_ .=.: u b .xnso. ...u. sacs am: a.>os:» in axes» no: a. .mo.ovao scotutttu >.uceo_emcome was «an sous». also 0:» >5 peso..oe not a c_ «coo: .mouou_.not oases mo oeeuo>s new a. can! seem a n.. n.n e.o «.o ~.o m.. n.n ... .a.m 0.: a e..s < o.om < n.nm < e.em < n.em < ~.~n a m..e « o.nm coo: use .o>.:u tone: aot< ..c ..o p.c ..° ..° ..o ..c ..o .o.m ..o n< ~.n a ..n < e.m a s.n < e.n < n.n a ,.n a< ~.n cam: .=.x .c_e a so scu_o= ..o ..o ..° ..c ..o ..o ..c ..c .°.m . F.o cu ~.n no. n.n < n.n un¢ e.» m< m.» uo< e.m o ..n ua< q.» coo: 9.3.x .ugotox .aoa o.o e.o ~.o ~.o o.° ~.o ..o m.o .o.» n.o < a.~ u e.e um F.m a n.n u o.e a ..o < a.» on n.n coo: c_¢ .oe_s soon no as ~o on .o no so as n.n.e no. .u co_satoma< toga: .m.m sausage» guascoscati osmaaa< n.nua..,= enact-go ..o:o..u ctana< scone tao.i zoos: eo_uo_se> uses: ou_;3 mo_uo_tu> snug: so“ co_uosoob< oc_xsm as oox.: agmsoo toue3-aso.u one »o sou-o snetmox_: o— wan0.05) among Charmany, Augusta, Caldwell, Tecumseh, and Adena doughs as well as among Tecumseh, Adena, Auburn, Hillsdale, and Frankenmuth doughs. However, each of Charmany, Augusta, and Caldwell doughs had larger values for peak height than those of Auburn, Hillsdale, and Frankenmuth doughs. Area under the curve ranged from 41.4 to 54.4 cmz. Tecumseh and Auburn doughs had similar values (P>0.05) for curve area which were the smalleet (P<0.0S) among the eight doughs. Differences in curve area among other doughs were not significant (P>0.05). The simple correlation coefficients between the mixograph measurements made on the SWW flour-water doughs at Balady baking absorption are shown in the Appendix. Mixograph peak time correlated significantly (P<0.0l) and negatively with area under curve (rt-0.87, n-24) and peak height (rs-0.59, n-24). Such correlation indicates that the shorter the peak time the stronger the dough will be. The mixograms made at conventional (Figure 5, Table 8) and at Balady absorptions (Figure 7, Table 10) showed that as water absorption was increased, peak time largely increased, whereas curve height at 8 min showed no or a slight decrease. Peak height and area decreased for all doughs except for that of Hillsdale which had a slightly higher peak height and area. Difference in the results of the farinograph and those of the mixograph may be related to the difference in the type of mixing action imposed on the dough by these instruments (Pomeranz 1987; Kunerth and D'Appolonia 1985). Results from both instruments showed that relatively longer mixing times were required by the doughs of the white varieties to achieve the point of maximum consistency. Under the predetermined water absorption levels for baking Balady bread, both groups possessed similar dough stability as indicated by stability time of the farinograms and similar curve height at 8 min of the mixograms. 116 The simple correlation coefficients between pairs of the farinograph and mixograph measurements made on the SWW flour-water doughs at Balady baking absorption are shown in the Appendix. Farinograph mixing time and mixograph peak 'time ‘were highly and ‘positively correlated (r20.94, P<0.001, n-24). Miller et al (1956) reported poor correlation between those two measurements for flours from strong wheats when the conventional AACC procedures were used. Farinograph curve height and mixograph peak height were also positively correlated (r-O.43, P<0.05, n-24). Mixograph study at 60, 65, and 70‘ water absorption: This study was design in order to compare the mixograph rheological properties of the eight doughs when mixed at fixed water absorption and to study the effect of changing water absorption. The recording mixograph of 35 g mixing bowl was used to study dough rheological properties at 60, 65, and 70% water absorption levels (Figure 8). This part of the rheological studies was intended to cover the wide range of soft wheat absorption for Balady bread making as measured earlier. The analyses of varianceIwhich are included in the Appendix indicated significant differences among flours and among levels of water absorptions as well as their interaction for the measured mixogram peak time, peak height, height at 8 min, and ll-min area. The significant interaction indicates that dough rheological properties as measured by the mixograph vary differently depending on the type of flour evaluated and the level of water absorption used. Therefore, means of the eight flour doughs should be compared within each level of water absorption and means of the three levels of water absorption should be compared within each wheat flour. That is because dough responded differently to the changes in water absorption levels depending on the flour type. 'Peak.time: Data in Table 11 indicated that doughs of Charmany, Adena, Augusta, and Frankenmuth had similar peak time (P>0.05) which was significantly shorter (P<0.0S) than that of Tecumseh dough at any 117 ADENA——e AUBURR l I I o AUGUSTA .;.4 . \ l j . l I ramxsunu'ru +1 - . CHARHANY cnovsu. n -0.- i1! Y—T' Lssnass; i I -1- -i M' @344 1.1.! .\ ) ‘ I ::E$:)HI Y \ ,.;w 1;. aura! ling-3 [FIG H we... \A \._'. \ \ \ . I’ I .- I . i . i L L l \ I If» i; .‘l'lv‘i .- , u .o \ I‘l-\ . I I. ‘--v\s , .w m 1’ l' .I I4“ in I ._ . \’ .v‘l Vid- X ’1‘. a. . e t - 1.1.; -i-‘ " - '*;V—‘x . ‘1 _» v) r , TICUHSBH 1 I a .111 HAW: - .- _. I .‘A. 1.! ..._.\ I“ 1. l "I 17.1" i . I 65 ' \ S_. um. ‘ ? *lli ‘ WI 7”? (7.) WATER ABSORPT I ON Pig. 8. Hixograes of the eight soft winter wheat flour- water doughs node at 60, 65, and 70h absorption levels. 118 >.uceo.e_cu~o use use Loose. omouaoso. use» on» >9 u0b_aouton:e ce:.oo e c. scene .oo.< .hmoc u new.mv it 0.3 $0 LOLLU Quin” .Amo.ovao «cotoee_o .32: ES :3 8.. n.>ox:» so cross on: as “mo.ovav acetoew_o >.uceu.e_ce_u so: use cause. sees ego >9 peso..oe sot e c. scoot ~ ..o>o. co_unaoooe tease goes cmgu.: use.ensou use: «some uses: .ocomosogu .co.unaoebe sous: pco assoc: courses co_uostouc. assumemce_a pesos» ouco_ts> eo nos>dec< F .aco_ue>aoeno ozu eo senses- ogu a. can: zoom n... n... ~... o... m... to m... n... a.“ < a»... u 13 8 .3 u .3» 8 and a .~.o < on... 8 a: Es. a o... n; F... o... ~... ~... in. o... P... d.» < a...» .. un.n a 33.. ._ «n.n a sea a as... ... no.» 9.1.6 53.. a S o; ~.o ~... P... to n... q... to .9... < god 9 a~.~ 8 god 9 n2 8 at... 8 on... e. on... 8 {a ~52. a 8 £838» glass... 33!... 2.8:... 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0.05) which were longer (P<0.05) than those of the other doughs at 65 and 70% levels of water absorptions. At 60% absorption, peak time difference between Auburn and each of Caldwell, Charmany, Adena, and Augusta doughs was not significant (P>0.05). Peak time increased as level of water absorption was increased (Figure 9). For many of the eight flours, the increase in peak time was greater as water absorption was increased from 60 to 65‘ than from 65 to 70$. The degree of increase was smaller for Hillsdale and Adena (Figure 9). Peak height data in Table 12 show that doughs prepared from Hillsdale and Frankenmuth had similar (P>0.05) peak heights, but their peak heights were significantly (P<0.05) lower than that of Adena or Tecumseh doughs at any of the three absorption levels. Also, Augusta dough had lower peak height (P<0.0S) than that of Adena or Tecumseh doughs at all the three absorption levels. It is evident from Figure 10 that peak height decreased progressively as water absorption was increased. Tecumseh, Augusta, and Charmany doughs showed a smaller decrease in peak height as water absorption was increased from 65‘ to 70% than from 60% to 65%. Data of curve height at 8 min of mixing are summarized in Table 13 and are depicted in Figure 11. Consistently at all the three water absorption levels, differences in 8-min height among doughs of Tecumseh, Adena, Charmany, and Caldwell were not significant (P>0.05). Also, doughs of Augusta, Frankenmuth, and Hillsdale had similar 8-min curve height (P>0.05). Adena dough had significantly (P<0.05) higher 8-min curve height than those of Hillsdale and Frankenmuth doughs. Figure 11 shows that the 8-min curve height of Tecumseh and Auburn doughs decreased progressively as water absorption was increased specially from 65% to 75%. Doughs of the other varieties showed similar trend but with less intensity. 120 .n~o>o~ couuouonnm nous: doe 0cm .mo .oo us some ncmsov noumznusouu your: sauce: uuou scams or» no 06‘» goon Ssuooxu: .m .uuu E 8.3.82 as... on we om . - _ _ o M 52.8.: .m: W. 225:: .4. m easement. no. % €3.25 ux. W =38 1m. m 229.... i... a 5.5.2. .+. ml. 2.22 1.: mun mmzmtg $2.3 1J21 333.:ch use 0... Loose. 33.8.6. «in oz» 3 3209.09» 533 e c. scene .3: .po.o u “.m.mv sees ezu we gotta oceuceum .Amo.ova~ acoeoewmo .852 .28 :3 8: e.>ozs. xn csozo on: so Amo.ovao acozoem.o >.uceu.»_co.o soc use tease. use» oz» so oesozzoe sou e c. scoot ~ .eco_ue>toezo or» mo seats). ozu a. case zuow ._o>o. co_untooze sous: zone c.zu.s poem-nice egos scene aeoz: .osoeozozu .co_unaoeze sous: one sneeze cassava co_uoetouc_ aceo_»_ce.o ossoza ouce_ze> eo eoo>zec< . ..o 9.: ..o o.o ..° ..o c.o ..o .a.m < z..n a uo.~ u. ao.~ a uo.~ n< na.n on oo.~ no uo.~ < u..m coo: u o. o.o c.o ..o o.o ..c o.o c.o o.o .o.m a z~.n a no... 8 no... a no... on a; 8.. a; 8n 6..» < an.» is. a 3 ..o a.o ..o o.o o.o o.o ..c ..o .o.m a< .m.n u o~.n u o~.n u .~.n a .e.n a o¢.n u o~.n a ao.n ~coox a co sou-:90. zen-cogent. azmaaa< o.aua...= ecu-cozu ..uao.ou ctana< scone co..atooz< toe-a oo_u0_ce> ueoza ou_z: ueom no..o...> .ooz: you seem oco_untoez< sous: no» use .mo .oo zo_s pot-note ozosoo cause-t:o.e ueoz: touc_: aeom uzo.w oz» eo .mestoox_z oz» we A.:.:v uzm_o: zooa ~— ubn

o~ cozumuonnm nous: flow can .mm too as can: nzusoc 53.8.... 2255: noussausonu booze nous; buon use—o oz» no “Em—oz zoom esuoox—z .096: E 5.3.8.... as... 2 mm on . q .H q -_ mum“ H a .a a H _L 5:55.32... $2.55 .5630 2823 5.52 252 32...... .855 ++*¢*M* (Sillfl fldV!DOXIH) 1J23 .Naoa n Aowomv 60‘ 08H *0 LOLLO thin” ..m:.:va: »coto.._u >.»coo.».co.o »oc one to»»o. oooozoso. oeso oz» >n ooz_tuozonso cl:.ou e c. oceoe .oo.< .Anso— .._oo »oo» em: .33.... B 52.: a... 8 $99.: 222.... 3.83:8... .8 2. .33. o... ..:.» B 3.8:... :2 o c. 28.. N .eco.»e>coobo on» eo oosuo>o oz» o. coo! zoom ..o>o. co_»nzooze to»es zoeo cmz».3 poz_eneoo ouos oceoe »eoz: .osomocoz» .co.»nzoozo so»os use o»eozx coos»on co_»oeco»c. »ceo_»_ce.o posozo ooce_uo> eo ooo>.oc< . :.: :.: :.: :.: :.: ..: ..: ..: .:.m 9. «:4. u: in... 2 and. :: l.~ 2 no.~ 2 no.~ : zo.~ < no... 5...... a E ..: :.: :.: :.: ..: ..: ..: :.: .:.: < a..n :nno.~ :nzo:.~ : ::.~ :< ::.n ::< no.~ :< a:.n :< n..n coo: a mo ..: :.: ..: ..: ..: ..: ..: ..: .:.m < :n.n : a:.~ :u u:.m : no.~ :< :~.n :< :~.n u: :..n :« on.n ~cao: u :o zoo-.8. 5:535... 88:3 383.... 6:82: 396.8 533. 20...... 82983.. to»en no.»o_so> »eoz3 o».z: »»om oo_»o_zo> »soz3 no: »»ow ace.»ncooz< to»e: nos oce .mo .oo z»_s potenota ozmsoo to»os-cso.e »ooz: to»c_: »»om »zm_w oz» eo .mestoox_z oz» eo A.:.:v :.: m »o »zo_ox n. mza

o~ cozuauonnm nous: woe 0cm .mo too as semi nzmsov wouszuusouu uses) mobs.) buon uzouo as» no azoaoz czflue Convex—z . pp.o_h E 5:28.... as... 124 5:58.... 282:: 5:58:32... $2.35 .3328 2:33 5.52 ::::< 3:29. .855 ++*¢*M* om mm on . ‘ - ........ e em .......... .. mm ........... 1 NM.“ ($31!“ IJUIDOIII9 JLFQEDJEEBFQ 125 Table 14 sumarizes the data for area under the mixograph curve (mixograph area) for the eight SWW flour-water doughs mixed at the three water absorption levels. It is noticed that differences among varieties tend to increase as water absorption level was increased. Charmany dough had significantly larger curve area (P<0.05) than those of Auburn and Augusta at 60 and 70% absorption. In, addition, Charmany’ dough had significantly higher area than the dough of Augusta at 65% absorption. .At all absorption levels, no significant difference (P>0.05) in curve area were found among doughs of Adena, Hillsdale, and Frankenmuth nor among doughs of Augusta, Auburn, and Tecumseh wheat varieties. In general, curve area decreased as water absorption was increased (Figure 12). It can be concluded from this study that as water absorption was increased, mixogram peak time increased, whereas peak height, B-min height, and curve area decreased. The change ‘was greater as water absorption was increase from 60% to 65% for these measurement except for curve area which showed the larger change when absorption was increased from 65% to 70%. Tecumseh and Auburn doughs required longer mixing time than other varieties. Tecumseh and Charmany dough peak height declined rapidly as water absorption was increased from 60% to 65% but their curves leveled off thereafter. These findings were in agreement with those of Kunerth and D'Appolonia (1985) who reported a significant positive correlation between water absorption ranging from 60% - 80% and peak time (r - 0.935) and mixograph area (r -O.860), whereas mixograph peak height was negatively correlated (r - -O.991) with absorption. Kunerth and D‘appolonia (1985) indicated that both farinograph and mixograph supply valuable information regarding wheat flour quality as related to mixing requirements, however, other tests of wheat quality including baking test are necessary to provide a complete picture of the overall quality for a given variety. 12€5 >_»ceu_e_ce.o »oc ous so»»o. ooeotoso. oeoo oz» >5 oo5.zuotonso clszoo e c. oceos .oo.< .ee.o u ..m.mv coo: oz» we Lotto sconce»m .amc.cvnv uc05o>>mv .Anho— .._uv use» am: o.>ox:» >5 csozo on: so amo.ovav »coto-_o >.»ceu_w.ce.o »oc one to»»o. oeoa oz» >5 oozozzo» so: o c. scoot ~ ..o>o. co_»naooze to»os zuoo c.z»_s poemsnsoo oto: aceos »eoz: .otoeotoz» .co_»ntoo5e to»os ace m»oozs cooa»o5 co.»oeto»c. »cou.e.ce_o sosozo ouce.ae> we ooo>5ec< . .oco.»e>soo50 or» we ooeuo>e oz» a. ceoe zoom P.e m.e o.o 0.0 o.~ n.o ~.o N.» .o.m no uo.s¢ on oo.em cum 5N.nm o< 50.>m < 50.no um oo.em o uo.oe o< 50.00 coo: x as 0.0 «.9 ~.o ~.p n.~ m.o o.» n.n .o.m :2 no.8 “.2 5...... u no.3 8<8~.$ 9. an...» o: 5...: :: no.8 < and: 52. a 8 5.0 m.¢ p.o n.c m.» N.» ~.p m.e .o.w 2 ohm. o... and. : .98 : 1.8 < «:.:. e. and: : 1...: 9. ..:.fi ~52. a 8 zone-8o» 53855.: 3263 ozone. 5 .2 S05 326.3 5211 scone co. »n..o05< to»e3 oo_»o_to> »ooz: o»_z: »eom oo_»o_ze> »sozn soc »»ow oco_»ntoo5< so»e: ups are .mo .90 z»_s pot-note ozosoo to»os.cso.u »ooz3 so»c_a »eom »ze.w oz» eo .osotuox_x oz» eo “use. o>tsu soec:.oot< e. mzm<» 127 .338... um. 2:85: ..:r 5:55:32... .o. 22.35 ..X. .3325 ..mT 2:32 i... 5.5:... IT :53. in 832...; .855 .n~o>o~ couuouonnm sous: to: use .mo .oo us some nzmsoe sooesausouu booze sous»: anon 550.0 oz» no sous suing» essmox_: .- .o_h E 8:282 .2... :. m: :: - u q ow M W om 6. E m N. a e 1...... w PM. om 128 Ioasurooonts of dough proportios using the back-oxtrusion: The rheological properties of the eight SWW doughs were evaluated at three different shear rates; 3.14, 6.27, 9.41 sec" using the back- extrusion. The force-distance curve obtained by the back-extrusion test (Harper et al 1978) of each dough was evaluated for the following measurements: Curve slope during the extrusion phase (slope), curve height at the peak (peak height), curve area before the peak (peak area), curve height at 30 sec after the peak (P30), curve area of the 30 sec after the peak (A30), percentage of P30 to peak height (Fdrop), and the time elapses till peak height drops to 37% of its value (relaxation time). Also, dough viscosity index and apparent elasticity were calculated using the computer program developed by Lever (1988) in accordance to the mathematical equations reported by Hickson et al (1982) for back.extrusion devices. Back.extrusion curves at 9.41 sec“'shear rate for the eight flour doughs are shown in Figure 13. Height at the plateau of the back extrusion curve was used by Schweingruber et al (1979) as an index of consistency of instant mashed potato. The authors reported a high positive correlation between back extrusion force and values of apparent viscosity measured by a Brookfield viscometer and yield stress measured by a rotational coaxial viscometer. Area under the curve was used by Schweingruber et al (1979) as a measurement of total energy required for extrusion. Slope of the back extrusion curve‘was recommended as an index for sorghum dough cohesiveness by Subramanian et al (1983). The authors found a relationship between curve slope and subjective measurements of cohesiveness of sorghum doughs. They also reported that force, slope, and area of the back extrusion curve increased as dough cohesiveness increased. Analyses of variance which are included in the Appendix showed, for all of back-extrusion.measurements, that differences among the three shear rates were significant (P<0.05) which indicated that these measurements are shear rate dependent. Significant differences were found among the 129 "n ‘- nlt:!l'9°-oom "0 .- .u‘.nso~. or“ so >- go.- . Adena r 1 Charmany 20)- ”- ‘ L _ IO - .o- r- 25 S O 7 8 '00 123 0‘ use _ II- no» a gol- 30 )- 3 L Auburn _ Frankenmuth a 10k ‘0:- g ' I k U: . i I . v n . l 7: voo 125 :5 so 79 :00 Y :25 "I Iona I 2 30 r- 30 - 2 Augus.a _ Hillsdale zoLb / :o p "Dr )0 i- / g. -/ L . . :00 12: 2: so *3 too :2: '0' cons ‘ "I out so .- act- L CaldweH , Tecumseh 20 I- 20 r- 1 r L '00- 10 h '35 23 so 7: .60 :23 0- one I- 0‘ mm ( SECOND) rig. 13. Back-extrusion curves of the eight flour-water doughs prepared at 65% water absorption and tested at the 9.41 sec‘1 shear rate. 130 eight doughs with respect to all of the measured curve parameters except PdrOp (0.10>P>0.05), and relaxation time. It should be noted here that the wheat x shear rate interaction can not be neglected if it is significant at P<0.25 (Gill 1978). The interaction between the main treatments; wheat variety and shear rate was negligible (P>0.25) for all of the curve measurements except for peak height, Fdrop, and A30 which showed considerable wheat x shear rate interaction (P<0.25). .Under the condition of considerable treatment interaction, comparisons among means of each treatment should be made at each level of the other treatment (Gill 1978). The significant interaction indicated that different doughs responded differently to the change in shear rate. In other words, changing the shear rate>brought about different effects in the dough depending on the characteristics of each particular dough" When the interaction is negligible, the overall means over the three shear rates can be used in the comparison among the eight SWW flour-water doughs. Analysis of variance of the measured slopes indicated significant difference among doughs (P<0.01) and among shear rates (P<0.001), whereas their interaction was negligible (P>0.25). Comparisons among the overall slope means of the eight SWW flour-water doughs (Table 15) indicated that slope of the curve of Adena was significantly higher (P<0.05) than those of Hillsdale and Tecumseh. Differences among doughs of all varieties excluding Adena with respect to the slope of the back-extrusion curve were not significant (P>0.05). The curve slope ranged from 1.45 N/mm to 2.35 N/mm. Comparison among curve slope means of the eight SWW varieties for three shear rates (Table 16) showed significant differences (P<0.05). The average slope for the eight doughs increased significantly as shear rate was.increased. Analysis of variance of peak height measurements indicated significant differences (P<0.001) among doughs and among shear rates. 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0.05) to those of doughs from the white SWW varieties. However, the peak height value of Hillsdale dough was lower (P<0.05) than those of the other red SWW varieties except Caldwell (Table 17). As shear rate was increased, peak height also increased. The significant interaction indicated that the increase in peak height for each flour-water dough followed a different pattern. When.peak.height was plotted against shear rates for each variety (Figure 14), most of wheat flour-water doughs showed traces of a convex pattern with variable skew, with that of Auburn showing slightly larger skewing. .Augusta and Hillsdale showed a concave pattern which means that increasing shear rate from 3.14 to 6.27 sec“I had relatively lower effect on peak height than the increase in shear rates from 6.27 to 9.41 sec”. Analysis of variance of peak area measurements indicated significant difference (P<0.001) among doughs and among shear rates, whereas their interaction was negligible (P>0.25). Comparisons among averages of the peak areas of the eight SWW doughs are shown in Table 18. Peak area varied largely among doughs and ranged from 117 to 209 N mm. Adena and Auburn doughs had significantly higher values of peak area than Augusta, Tecumseh, and Hillsdale doughs. The latter had significantly lower peak area values than Adena, Auburn, and Charmany doughs. Comparisons among the overall means of the three shear rates for peak area (Table 16) showed significant differences (P<0.05). Peak area significantly increased as shear rate was increased. 1434 .38. :5. 33 8.. «38.3 3 $5..» an: as “mo.ovav acouoee_o >.uceo_»_cu_u use at. t0uu0. «sea on» xn peso..oe not a c. «coo: n .~p._. u .w.w 583-2030 .53 we 099.96 05 3 cans room .3... gauge gone :23: “09:03.3 9.0: 9.38. «out: .ouoeouogu .eoueu tees» use snooze coosuon Am~.ovau comuuotouc_ aceu_e_ce_e oozoga euce_te> e0 eon>.ec< o ~m.~ -.p mc.~ oo.o -.~ n~.p nm.~ om.n .o.m u o~.o~ on oo.n~ on oo..~ u o..o. n< o..o~ a o¢.¢~ a oo.m~ < eo.~n coo: moe.o .5.. o~.~ «o.~ so.o mm.o co.o 3s.. n4.n .a.m nu. No.0. a< on.o~ no o..m. a no.np ¢ .~.- u< ~o.o~ < o~.e~ < oo.m~ coo: o-.o oo.n so.— oo.o oo.o 4a.. no.. as.— «o.~ .o.m on o..~. um ~m.n. on so..p u am.o a< no.m. on< m«.«. n< o~.o. a e~.o. acne: mn..n sausage» goazcoxcati nomauac o.oua.._= atostogu ..osu..o ctana< ocot< ..-0ouo ease geese oomuomue> uses: mums: atom mo_uo_te> «00:: use atom «goose touea-u:o.u uses: touc_3 umom u¢o_u use *0 amount ueogm vote» as «stag coisatoxm soon to Acooaoz. uga_o= ..oa a. mo¢

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Comparisons among F30 values of the eight doughs (Table 19) showed extended variations among the SWW ‘varieties. Hillsdale dough had significantly (P<0.05) lower value for F30 than Auburn, Adena, and Charmany doughs. Auburn dough had significantly (P<0.05) higher F30 value than those of Hillsdale and Frankenmuth.doughs. The F30 values ranged from 2.57 N for Hillsdale dough to 5.23 N for Auburn dough. Comparisons among means of the eight SWW doughs for the three shear rates (Table 16) indicated significant difference in F30 between the two shear rates 3.14 sec‘1 and 6.27 secq. However, the F30 of the 9.42 sec” showed an intermediate ‘value' of 3.97 N ‘that was not significantly different (P<0.05) from either of the other shear rates. The decrease in F30 at higher shear rate can be explained by the shear-thinning characteristic of wheat flour doughs which resulted from structural breakdown (weipert and Pomeranz 1986) or by the orientation of gluten fibrils (Evans et al 1981) and strands (Belitz et a1 1986) in the direction of stress. Percent drop in force after 30 sec from peak (Fdrop) is an expression of F30 as a percentage of the maximum force measured at the peak; peak height. High Fdrop values indicate minimum energy loss and slow relaxation. Analysis of variance of Fdrop data showed significant difference (P<0.001) among different shear rates. It also showed considerable interaction (P<0.25) between wheat variety and shear rate. However, differences among wheat varieties were marginal (0.10>P>0.05). Figure 15 showed that Charmany and Tecumseh doughs had exceptionally higher Fdrop values than doughs of the other varieties only at the lowest shear rate; 3.14 sec“t. These high values decreased dramatically as shear 1J38 .eco.ue>toeno ~— we soon or» e_ ooeto>e seem ..osop .._uv unou am: e.>ox:» so csoge no: no amo.ovav «coco»e_o >.uceu_m.ca_e use ote touuo. use» ogu so ooze..oo sou e c. eooeuo>< a flute-tau 2!. no»: .323 :e ..o>o eceos ueoi .otoeouog» .eouet goose use eueog: coosuoo am~.oxav comuoeuouc. uceu_o_eu_e o: noses. ouce_te> es eoe>.ec< e nn.o one no.» on nn.n one om.n u sm.~ me no.m use so.e o n~.m me ~o.m nooeuo>< ~o.o o~.o on.o we.o no.0 om.o o~.o nn.o .o.m oofi «n.n 8.n cm.~ :.e ~03 :.m use coo: 3.10 8.0 mné No... 00.: ~0.— as... am... ON; .a.m hofi $.n 005 :.n 33 as; -.o «n.n coo: 2&6 3.— no.9 .66 3.: on... :.o m...~ 07— .o.m ~n.e mo.~ ~P.n oo.~ ms.m pe.n sn.e eo.e coo: mn..n . m.w segue.— gugoxcet eunag< Benn. . 3. Sean 30353. $5.13 9.0.3 :.ooev oueu Leora ao_.o.ta> onus: oo_;: seam ao_oo_..> snug: to. soon nausea coues-tso.a woos: coucm: boom u:o_w osu we enouea ueocm ootgh ue commstuxw xuee *0 “one. xeoa ogu Loewe ooe on ue Accuses. «sumo: or man: 139 .oueu noose uo eno>ou sous» us ecosoo woueslusOHH ueocs houses uuoo anode on» «0 025.5 caesuuxonxoen no anode: xeom no omeucoouoo e no xeon nouns 000 on as wages o>uso ea .9: 2.. omfl mic m0.05) relaxation.time (Table 21). However, differences in relaxation time among the shear rates were highly significant (P<0.001). All doughs showed the same trend of change in relaxation time when shear rate was changed. This was evident from the negligible interaction between wheat varieties and shear rates. Relaxation time continuously and significantly (P<0.05) decreased as shear rate was increased. This indicates that the larger the amount of energy stored in the dough during the phase of plunger movement, the faster the loss of that energy. Differences among the eight SWW varieties and among the three shear rates with respect to dough viscosity index were significant (P<0.001). Also, ANOVA.established that wheat x shear rate interaction was negligible (P<0.2S). Comparisons among Viscosity index values of the eight SWW doughs are shown in Table 22. The dough of Adena variety showed large value for viscosity index which was significantly higher (P<0.05) than those of the other varieties excluding Auburn. In contrast, Hillsdale dough showed a significantly lower (P<0.05) value than those of Adena, Auburn, Caldwell, and Charmany. Dough viscosity index continuously and significantly (P<0.05) decreased as shear rate was increased. 141 .oueu noose uo o~o>o~ ooucu an ecosoo uoueslusoau noon: uou:«3 uuoo acoqo one no oo>uso sawosuuxolxoen uo xoom nouns com on All couaoz. eoue o>uso 2.. $3 NEE mcoecezo .3263"... 5.5.2 H*M++* ecoo< 32:; 32:5 CD 0 N 0 v D (D O 00 00.. our 0:; on .eue (W'-u UOIMaN) )Wad W085 339 08 HBidV VBHV .83. :6. «no» 8.. use...» so 665 oer ee amo.ovao aceto»s_o souceu_~_cm_e use oce touuo. ones on» so nose..os sou e cm eceo: o .nn.o u .w.m .ocomue>toeoo use» we oeeuose oou e_ zoos seem .oueu ueooe oueo c_ou_x ooc.eosoo otos eceos ueoo: .otooouoou .eoueu goose use eueoga cooauoo smN.ovav comuoeuouc_ uceo_s_co_e oosooe ouce_te> oo eoesdece e 1142 NP 0 s p— NN up n n- .a.m nu ma nun No coo No 9 ms ( QNP un< oo— o: app < sN— coo: moe.o o 0 or o NN NN s mp .o.m 0 km on «e um '0 0 mm un< on on: as < «a a: co coo: osN.o s e n o «p n o o .o.m < on < «N < 0N < or < we < sN < mm < co oceo: mnp.n i858» guesses: 339.. 3.3. . r. 52:5 32.38 533 .53 .78: eyes ueoom eo.uo.te> woos: oumoa use» oo_uomte> aeooa soc awom nausea touea-uso.g ueoo: coucma.uoom use_m oou we enouee teoom oouos ue o>uso co_estoxw xuee we xeoa touoe com on *0 Ass couxozv eoue o>tsu ON moo

uoeoo N— .0 cool oou a. ooouo>e ooom .uoumeaeou otos eoue. .eooe ..o toss ecoos ueoo: .ocomouoou .eouou teooe use eueoos coosuoo smN.oxa9 co.uuotouc_ aces—o'co_e o: ooeooe ouce_.e> we eons.oc< e m9.9 <99; («9; <3; (09% (00.9 <09... (9.... <09; oouooo>< «9.9 3.9 3.9 N9.9 09.9 n9.9 N9.9 3.9 .9.m sm.9 n.n..9 8.9 9.99 no.9 0.9.9 8.9 and coo: Bio N9.9 09.9 NN.9 N9.9 2.9 2.9 9...9 2.9 .9.» 8.9 8.9 M9... no.9 3.9 00.9 no.9 no.9 coo: 9sN.o no.9 N9.9 3.9 3.9 sm.9 N9.9 s9.9 09.9 .9.m on; no; as; 3... mm... so; ms; :4 coo: mn—.n .m.m come-goo.— guiloxcecu 38.6.3 332:: Fences :ozgou $59: ocoo< :.uoov ouee .eogm oomuomuo.’ uoos 3:5 Com oomuomco> goof tom tom noose: toues-.:o.a woos: tout.) noon «ou_u oou we co_es.uxw goon so eeouox ueoom oo.os we soon. on.» co_uexe.o¢ FN won: 1Jl4 .aco_uo>co¢no Np co cool ocu a. oooco>o snow .83. 3.8 :3 8.. «1.8.2 .5 So... no: no “no.9va9 ucocowwmu >.ucou_w_c9.n uoc oco couuo. ocou ozu >5 uo:o..o~ soc o c. monoco>< 3 69.3989 9.2. «3!. .52.» :o .26 «cool woos: .oco»ococp .oouo. cooga uco «woos: cooauon Am~.oacv co_uuo.ouc. acou_..cu_n oc oozes» ouco_co> co noo>.oc< o o.¢m 99 p—op 99¢ ~59. no ppcp a who no ~m~P um «opp 9< non— < som— noaoco>< 00 he om— up pop on on amp .o.m mnn 9no 9mm .05 one emu 999' oc~p coo: m9¢.o no ~9~ ms? 00 co «9. «cm mo~ .a.m ~90 now. 099 won 00.. «nap «on— 9—«— coo: os~.o pnn 99~ «9 co os— ~9~ pup o—o .o.w ~9~p «oer 9~n- ~09? pump Fpmp hoop ~99~ coo: mnp.n .w.m coguo» cuicoxcocm 332.2 Bonn. . m: 32:26 326.8 53¢ 3&2 “.383 ouoc coocm nowuo_co> woos: ou_:: “com oomao_co> woos: toe atom «canon couo3-c:o.u woos: coucma awom acu_w ocu we comaacuxm goon co oaouoc coocm oocgh uo Aoomonv xouc_ >ummoua_> ~N w490.25). Comparisons among apparent elasticity means of the eight SWW doughs are shown in Table 23. Dough of Adena had a larger value for apparent elasticity (P<0.05) than those of other wheat varieties excluding Auburn and Charmany. Hillsdale had lower (P<0.05) dough apparent elasticity than Adena, Auburn and Charmany doughs. Increasing shear rate from 3.14 sec'1 to 6.27 sec” brought about a significant increase (P<0.0S) in the average apparent elasticity of the eight doughs. However, increasing shear rate from 6.27 sec'1 to 9.41 sec‘1 was accompanied by a drop in dough apparent elasticity to an intermediate value that was not significantly (P>0.05) different from those at the two lower shear rate (Table 16). When the values in Table 23 for dough apparent elasticity were expressed in Newton per square meter (N/mz), they were in the range of 2.8- JJGG .83. :.8 $3 8.. «33.3 B 52.. no: no “no.9va9 «cocowe.c >.ucou_w_ce_u uoc oco couuo. econ oz» x: pose..ow sec o c. cousco>< n .uco_uo>cooao ~P mo cool use a. oeoco>o zoom .poc_onoou ocoa mouoc cooco ..o co>o econ: woos: .ocoeocogp .eouo. Loose uco ouooc: cooxuon Am~.9xa9 co_aoocouc. acou.»_ce_u oc cosoco oucomco> co ooo>.oc< o 9¢.9 99 po.e 99 os.e 99 ~0.n u «o.n 9: op.m on o¢.e 9: oo.m < 9p.h noooco>< 0.9 n.9 ~.— ~.9 ~.F ~.9 «.9 n." .o.m —.c o.e 9.e ~.¢ p.m 9.m e.m 9.0 coo: moe.o 5.9 m.— m." 0.9 m.« o.— 0.. —.~ .o.m —.m F.o P.e n.n n.n o.m ~.~ ~.~ coo: os~.o ~.~ o." 9.9 e.~ 0.9 ~.~ m.9 ~.e .9.m o.e ¢.n o.~ 9.n o.¢ 9.~ p.m 0.5 coo: mnw.n .w.m cooszuo» gualcoxcocu ouo393< odovnddwz >coicozu ..oxtdou ccana< ocov< np.uomv ouou coocm oo_uowco> uooca ouwcn umom oomuomco> woos) no: anon «cocoa couox-.:o.u uooc: Loucmz aeom acu_w ozu we comoacuxw soon .0 ououoe coosm oocch uo Aneochuxoxv >u_u.umo.m acocodo< MN w49

0.05) for the eight SWW doughs as was indicated form the measurement of Fdrop, and relaxation time. These results are in agreement with the generally larger mixograph area (Table 10) and higher farinograph peak height (Table 9) reported early for the red varieties, when doughs were mixed at Balady baking absorption levels. Both indices; mixograph area and farinograph peak height indicated that doughs prepared from flours of the red varieties generally were relatively stronger than those doughs made from flours of the white varieties. The relatively higher values of viscosity index and apparent elasticity of doughs prepared from soft red varieties in comparison to those prepared from soft white varieties (Table 22 and 23) agree also with the general applications and usage of soft wheats. Soft red wheat is preferred to soft white wheat in making cracker sponges, cake donuts, and soup thickeners, whereas the later is preferred in making pie doughs and high-spread cookies (Loving and Brenneis 1981). Positive correlations were found between peak height of the mixograms made at 65‘ absorption and the back extrusion peak height, peak area, viscosity index, and apparent elasticity (r-0.73, 0.71, 0.73; a<0.0$, and 0.81; a<0.01, respectively). Also, the 8-min height of those mixograms was in a positive correlation with the back extrusion averaged curve height at 30 sec after the peak and with Fdrop and curve area of 30 sec 148 after the peak at the 3.14 sec'1 shear rate (r=0.79; a<0.02, 0.77; a<0.03, 0.81; a<0.0l, respectively). The back extrusion technique has some advantages over the traditional techniques in measurements of dough properties. It provides useful rheological indices such as apparent elasticity and viscosity. The test can also be run at different shear rates in comparison to only one used by the traditional dough mixers. This provide a variety of shear rates that can be selected according to the appropriate applications. Moreover, it enables detection of smaller differences among doughs. The back extrusion technique can be used to assess rheological properties of dough pieces sampled at different stages of the bread making process starting right after mixing till before baking. Nevertheless, the traditional techniques; farinograph and .mixograph are indispensable as they provide needed information about dough proper water absorption and mixing time. Subjective and Objective svelustion of Balady Breed Made free the light 8“" Plours The eight soft wheat flours of 90% extraction were baked into Balady bread according to the statistical plan of a balanced incomplete block design (3180) arranged in complete replications (Cochran and Cox 1957). The 8180 was applied so that four breads could be baked and evaluated subjectively and objectively each day (block). Each two consecutive days formed a complete replicate. A total of fourteen days were necessary to complete seven replicates for all the eight SWW flours. Many panelists performed the sensory evaluation, however, only six panelists completed the test with no absence or withdrawal. Subjective scores and objective measurements were subjected to 8180 statistical analyses and, whenever block effects were found significant, treatment means were adjusted to block effects, otherwise, incomplete blocking was ignored, and the data were treated as a complete block design 149 of seven replicates. The comparisons among treatment means were done using Tukey's Honestly Significant Difference (880) test (Gill 1978). Subjective Evaluation of Balady Bread The baked bread was evaluated for the following characteristics: Appearance of top layer, bottom layer, and bread inside as well as bread aroma, taste, and mastication (chew). The panelist marked the score for each of these characteristics on a straight scale; starting from very poor to acceptable to excellent. That scale has been equated later to 0, 5, and 10 respectively. Copies of the score card and the descriptive sheet are included in the Appendix (A and B). The scores of these bread attributes given by a panelist for each sample were summed and the total (sensory combined score) was considered as an index for the quality of that sample. Sensory data are summarized in Table 24. Analyses of variance are summarized in the Appendix and showed significant variations (P<0.0$) among the baked breads for all the attributes evaluated by the panelists, except for bread taste (0.10>P>0.05). The effects of day-to-day variation on the baked breads were not significant (P>0.05) as was shown by insignificant block (day) effects in the analyses of variance. This may reflect the reproducibility of the test and the successful control over the working conditions. In contrast, variation among the panelists were highly significant for all the quality aspects. However, the statistical design enabled separation of panelists' effects, and thereby, valid comparisons among means of the main treatment; the eight wheat flours were possible. Generally, all breads scored acceptable or above for all the traits (Table 24) with the exception of the Hillsdale bread which scored slightly lower than acceptable for chewing score (4.70). Panelists described Hillsdale bread as tough, too chewy, and of dry texture. 15K) 0.0.ou .co:— ..m9.9xa0 acou.e_ce.u ocos ouooeeo xuo.o no auooeuo goo.o ou pouusqoo ocos .>u...ooudoouo .o udouxo wouao.cuue noose ..o .0 mocouo uc_ooo >9 noose cuoo to. poo-_au.eu ees ocean paces-cu u .eouou..eoc co>oe ace euu._ocoe n.n >o ones eco.ue>coeoo ~¢ we eoeco>o oz» 0. o:.o> room A .aouou_.do. s «o A.o.mv co_0o.>oo ocoocoue ocp ..950— _..90 aeou on: e.>ox:. >3 cause no: no .m9.9va0 acoco»0.p >.acou.>_ce.a uoc oce couuo. osee ecu >5 uoeo..o. so. e c. «coo: o .n.. 00.~ .0.. mm.~ ~..~ ~0.. .0.n n..~ .0.0 3.. .. 2.8 0.. 3.3 9. 2.: u 3.2 09. 8.00 0.. 3.9. u... 9.00 02 8.00 So... 0280 8:380 0..0 05.0 0..0 ~0.0 50.0 00.. 00.0 05.0 .0.» 0~.0 00 05.0 00 .n.m 0 ~o.0 a 0..0 .< 00.0 0< .0.0 00 00.0 00 ~0.0 coo: 1000 00.0 no.0 00.0 n... 00.0 00.0 n~.0 00.0 .0.0 .~.0 < 00.0 < ~0.0 0 00.0 < 0~.m < 50.0 0 o~.m < 0~.0 < m..0 can: 0.0.. 00.0 ~0.0 00.0 .0.0 o~.0 00.. 00.0 .0.0 .0.0 0..0 00 00.0 0 00.0 < ...0 0< ...0 00 00.0 00 o0.0 0 ~o.0 00 .o.0 coo: 050.0 .0.0 00.0 .0.0 -.. 00.0 00.. 0~.0 ~0.0 .0.0 00.0 00 00.0 0 50.. 00 ~..0 0 o0.0 00 n..0 00 No.0 00 .o.n 00 .~.0 coo: «0.0:. 00.0 o..0 ~0.0 ...0 n..o .n.. -.0 00.0 .0.0 n~.0 00 .~.0 0< 05.0 0 ~n.0 00 00.0 00 ~>.0 0 0~.m 00 o0.0 0 n~.0 :00: .o>o. lasso. ~..0 00.0 ~0.0 00.0 05.0 00.. no.0 00.0 .0.0 R... < 3.0 0.. 00.0 02 3.0 00 00.0 8.. ...0 u 3.0 0.... 3.0 09. 3:0 ..:-oz .2... no. .0... ..:-:8. 538.23... 3390 0.60:... >515... :83... £3... 2.3 33...... acute no.0o.co> goes: ou.g: «com .0......> .00.: no. 0.00 :3: .02... to... 2.0.0.»... :2. .03.... .58.. .60.... .o .3... >328 0... 0...... 151 Appearance of Balady bread top and bottom layers has a great effect on the overall acceptability of the loaf. Bread top layer of excellent characteristics should possess an evenly distributed golden brown color with some pin points of brown spots. Bread top layer should be free of burned or cracked surface and flour particles. Excellent characteristics of bottom layer are similar to those mentioned for top layer except that top layer should look shiny and feel smooth. Bread baked from the Tecumseh and Frankenmuth flours received similar scores for top layer characteristics which were significantly better (P<0.05) than that of Caldwell bread. In addition, top layer of bread baked with Tecumseh flour was significantly (P<0.05) more acceptable than that baked with Hillsdale flour. With regard to bottom layer characteristics, bread baked with Augusta flour received the highest score among others and was significantly higher (P<0.0S) than those breads baked with Adena or Caldwell flours. Inside characteristics of bread baked with Frankenmuth flour was significantly more acceptable to the panelists than that baked with Hillsdale flour. Excellent Balady bread should taste slightly sweet, not salty, yeasty, doughy, nor floury. The fresh loaf should smell acceptable and possess pleasant aroma. Both dough fermentation and bread baking steps contribute to the formation of the desirable flavor compounds of the bread (Pomeranz 1987). Taste was scored as slightly acceptable for all the breads and did not differ significantly among the flours used. Bread aroma was scored from 5.8 to 6.7 for the eight varieties; moreover, significant differences (P<0.0S) were established for aroma scores for breads prepared from the eight SWW flours. Panelists scored the aroma of breads prepared with Augusta or Frankenmuth flours significantly higher (P<0.05) than that of bread prepared with Auburn flour. Panelists noted small but significant differences (P<0.0S) among the Chew or mastication characteristics of the eight breads. The bread prepared with Hillsdale flour received a lower score for bread chew 152 (P<0.05) than the bread prepared with Augusta flour. A study by Zabik and Tipton (1989) showed different fractionation patterns of the gluten separated from straight grade flours of these two particular varieties. That study indicated that the gluten form Hillsdale had, in contrast to that of Augusta, higher amount of the gliadin rich fraction and lower amount of the glutenin rich fraction. In comparison to the gluten fractionation pattern of Hillsdale and Augusta, the gluten of Frankenmuth and Tecumseh showed an intermediate value of both gliadin-rich and glutenin-rich fractions. Gliadin proteins contribute fluidity and extensibility to the gluten, whereas glutenin proteins contribute strength and elasticity (Pomeranz 1985). Panelist's scores of all characteristics for each sample were summed to produce a combined score which can be used as a quality index for the overall acceptability of the bread sample. Analyses of variance showed significant variations (P<0.0S) in sensory combined scores among the baked breads. Bread prepared using Tecumseh flour showed higher quality index (P<0.0S) than that of bread prepared with Caldwell or Hillsdale flour (Table 24). Also, the bread prepared using Frankenmuth or Augusta flours had significantly (P<0.0S) higher quality index than the Hillsdale bread. It can be concluded from this subjective evaluation that breads of acceptable quality can be prepared from the 90% extraction flours milled from the eight SWW varieties with the exception of Hillsdale variety. Bread prepared from Hillsdale flour was less than acceptable mainly because of its chew characteristics. Bread prepared from Hillsdale flour was of lower quality in comparison with the bread prepared from Tecumseh, Frankenmuth, or Augusta flour. The higher quality index of bread prepared from Tecumseh flour in comparison with that made from Caldwell or Hillsdale flour can be also related to the differences in bread top layer characteristics. 153 Objective Evaluation of Balady Bread The objective analyses of the baked Balady included the measurement of bread upper and bottom layer thickness, texture, and color. Thickness of the top and bottom layers of the bread was measured by a caliper. Texture of the bread layers was evaluated by the Instron using a puncture test. Color of the outer surface of the bread top and bottom crusts was evaluated using a Hunterlab calorimeter. Bread layer thickness: Values of layer thickness are presented in Table 25. The analyses of variance which are in the Appendix showed no significant differences (P>0.05) among varieties with regard to thickness of top or bottom layers. In general, bottom layers of all breads were relatively thicker than their corresponding top layer. Photographs of cross-sections in Balady loaves which were reported by Mousa et al (1979) and Faridi and Rubenthaler (1983b) showed also that bread bottom layer was thicker than the top layer. Since the bread top layer is exposed to larger amounts of heat during baking, more water loss and less thickness is expected. Thicknesses of top and bottom layer were positively and significantly correlated (r s 0.55). This indicates that thickness of both layers was affected equally, within each loaf, by pocket formation and the expansion of the loaf under the pressure of the developing steam during the first stages of baking until the expanding structure sets. After baking, bread top layer had less crumb attached to the crust than that of the bottom layer. It is desired for Balady bread to have a small amount of bread crumb (Morad et a1 1984). If the formation of the air pocket during baking is complete and the loaf reaches the maximum expansion before the structure is ”set” by the high baking temperature, less crumb is obtained. Further heat will result in more water loss 1154 .moueu_.aet s sot» peuedcu.eu use: co_uo_>op pentosan use are coo: n .mceee ucoee peso» as: Amo.ova0 eucoceeemp aceowe_cemu o: e ~... 0.0 0... 0... 0.0 0... 0... 0.0 0.0 5.0 ..:. 0... 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Color of bread crusts: Color of the outer surface of bread top and bottom crusts was evaluated using the Hunterlab colorimeter which measures color as lightness, redness, and yellowness. Hunterlab color values for bread top and bottom crusts are shown in Table 27. Analyses of variance included in the Appendix showed significant differences (P<0.05) among varieties with respect to the three parameters of color for bread top and bottom layer measurements. The values for top and bottom layers followed approximately the same trend. 1'. values (Degree of lightness): Bread crusts showed high significant differences among varieties regarding degree of lightness. 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Frankenmuth :- Tecumseh > Hillsdale > Caldwell z Charmany I Auburn - Adena. The bread prepared with Adena flour had darker (P<0.05) top crust than that prepared with Caldwell flour. The degree of lightness of bread bottom crust showed less variation among varieties in comparison with that of the top crust (Table 27). Augusta, Frankenmuth, and Tecumseh are white wheat varieties, whereas the other five are red wheat varieties. Both the color layers and the pigment strand (which are part of the wheat seed coat structure) have red to brown pigments in the case of red wheats. White wheat varieties lack these pigments (Evers and Bechtel 1988). Therefore, lightness was associated with wheat type. Because all flours were of 90‘ extraction which resulted in incorporation of large amounts of wheat grain outer layers. L values for bread top and bottom crusts were relatively low (Table 27). Degree of lightness of bread top crust ranged from 47.2-55.7. The degree of lightness or grayness as measured by reflectance and differential tristimulus colorimeters is known to be correlated with flour contents of bran (Kruger and Reed 1988). a values (degree of redness): Comparison among a values of bread crusts (Table 27) indicated that top crusts of breads prepared using the white wheat varieties, i.e. Augusta, Tecumseh, and Frankenmuth were significantly less red (P<0.0S) than those of breads prepared using flours of the red varieties. Bottom crust showed similar trend with the exception that differences in a values of between breads made using Tecumseh and Caldwell flours or among breads made with Frankenmuth, Auburn, Caldwell, and Charmany flours were not significant (P>0.05). The higher a values of bread baked with the flours of red varieties may be also attributed to the presence of the red to brown pigments naturally exist in the outer layers of their wheat kernels (Evers and Bechtel 1988). White wheats lack such pigments. 159 I’vslues (degree of yellowness): b values of bread top crusts ranged from 14.3-17.3 (Table 27). Again, bread crusts of Frankenmuth, Augusta, and Tecumseh (white wheats) tended to have significantly higher values indicating greater degree of yellowness than those of other varieties. One exception was that top crust of bread made with Tecumseh flour had a degree of yellowness similar to that of bread made with Caldwell flour. In general, the top and bottom crusts of bread made from the white wheat varieties were lighter in color, less red, and more yellow in color than those of breads produced from the red wheat varieties. Less variation in color parameters were noticed for breads baked from flour of red wheats than those breads baked from white wheat flours. Within the red wheat varieties, bread baked with Hillsdale flour had significantly (P<0.05) lighter top crust color than bread baked from other varieties. Bread baked from Caldwell, Charmany, and Auburn did not vary significantly with respect to degree of lightness of top crust color. Caldwell bread top crust was significantly lighter and more yellow than that of Adena, whereas differences among others were not significant. The color parameters of bread bottom crusts did not show any significant variation among the red wheat varieties. Pomeranz (1987) listed the variables that affect the browning of conventional pan bread. These variables are dough sugars, pH, and moisture, oven rH and temperature, and time of baking. Browning can.be reduced, however undesirable, by cutting down the amount of added sugar in the formula, by increasing the fermentation time, by reducing dough pH (which affect the availability of the aldehyde groups of the reducing sugars), by decreasing oven temperature and baking time, by increasing the rH of the oven, and by increasing the moisture of the baked product (Pomeranz 1987). In the present study, no sugar was included in the bread formula, and bread from all the eight SWW flours were baked under the same conditions. The only variables that are expected to affect different 160 browning of the breads are the amount of reducing sugars originally in the flours and the moisture contents of the doughs. Kruger and Reed (1988) described flour pigments and factors that affect the color of wheat flour and pan bread crumb. Wheat pigments responsible for the yellow color of wheat flour are carotenes, xanthophylls (mostly lutein and its mono- and diesters), and flavones (mainly tricin). Xanthophylls are hydroxylated derivatives of carotenoids. They are light-sensitive compounds and can.be>easily oxidized to colorless products. Flavones are a group of yellow to brown pigments which exist in trace amounts in refined f1our but are found in larger amounts in bran fractions. Wheat germ contains more of these pigments than bran, whereas the endosperm contains the least. The color of bread crust is controlled mainly by two types of reactions; Maillard and caramelization that occur during bread baking (Kulp 1988). Haillard or browning reaction brings about its effects on crust color as a result of the reaction of the amino groups of free amino acids or of proteins and the reducing sugars remaining after the fermentation process. Caramelization reaction is induced by heat resulting in complex chain reactions of sugars that cast the crust with the desirable golden color. By the end of fermentation, therefore, the remaining amount of endogenous and exogenous sugars in the dough controls the color of bread crust (Rubenthaler et al 1963). Proximate chemical analyses of Balady bread: Table 28 presents a summary of the proximate analysis results of the major components of the bread prepared from the eight SWW flours. Composite bread samples for each of the varieties were prepared from the seven replicates obtained from the baking test and were used for the proximate analyses. The representative composite samples were chemically analyzed for the major components; protein (total nitrogen x 5.7), total dietary fibers, lipids (petroleum ether extracts), and ash. .oucoco...p 00 nouo.:0.oo .00. 0c.0o.oxo. oouocuxsoacou .000. 0. 0:0 . 00.000086 coguo 530..qu >0 08.838 oco: 03.... oo... o .0000.. 0touo.o .000. 0. 00. o .0.0 x : 0 cool o...» 3300.00 3 too: 30.03.3000 .0 con-5: o u. 30.0 0o0o.0 0. coos gooo .0 co..o.>oo ocoucouo oc. .0000. ...0. 00o. 00: 0.0oxo. 00 c3000 00: 0o .00.0v0. acoco...o >..coo...c0.a 00c oco couuo. osoo on. 00 00:0..0. :00 o c. ocoo: o 1(51 0..00 0..00 00.00 00.00 .0.00 00.00 06.00 00.00 coo: R .0020 00.0 0~.0 No.0 0~.0 .0.0 o..0 0..0 0..o .0.0 0 0..0 ¢ 00.0 < 00.0 ¢ ~0.0 < 00.0 < ~0.0 < 00.0 ¢ 00.0 < 00.0 coo: x .oonmnm. 00.0 .0.0 .0.0 .0.0 .0.0 No.0 00.0 No.0 .0.0 ~ .0.0 0 00.. 0 ~0.. < .0.~ 0 00.. u 00.. 00 00.. 0< 00.. 0< 00.. coo: x .:m< 0..0 ~0.0 .0.. 00.0 0... 00.0 0~.0 0~.0 .0.0 0 00.0 < 00.0 < 00.0 < .0.0 < 00.0 < 00.0 < o..0 < 00.0 < 0~.0 coo: a .000. 0..o 00.0 0~.0 00.0 -.0 .~.0 00.0 00.0 .0.0 0 N~.0 0< 00.~. 0 .0... 0< 00.~. 0c 00.~. 0< 00.~. 0< 00.~. 0 00... < 0~.0. coo: R .oc0o0000 a: .0.0 0001300. cualcoxcocu ouoaua< o.ono...x 0colcocu ..osv.ou ccans< ocov< ouanmcuu< not—30o) .025 out.) .000 0o..o...o> .025 Dog 0.00 0030...; 0005 0305 :00 to: 05 ..0... 09.00 10.3 0020 000.00 .0 00000 0.00.05 8000.000 0... 32. 162 Analyses of variance included in the Appendix showed significant differences (P<0.05) among breads baked from these flours with respect to protein and ash contents. Differences in lipid (petroleum ether extract) and total dietary fiber (TDF) contents among bread were not significant (P>0.05). Differences in protein contents of the bread prepared from the eight SWW varieties were not significant with the exception that Adena bread had significantly (P<0.0S) higher protein content than those of Auburn and Frankenmuth (Table 28). Bread baked with Augusta flour had higher (P<0.0S) ash content than those made with flours of the other varieties except Adena and Auburn. Charmany bread had lower (P<0.0S) ash content than breads of the other varieties except Caldwell. Total carbohydrate contents (as determined by differences) ranged from 77.1-78.5t (Table 28). Generally the baked bread (Table 28), in comparison to its original flour, was found to contain relatively higher protein and ash contents, and lower content of lipids and TDF. The increase in protein and ash contents of bread is due to the inclusion of yeast (1%) and table salt (0.5%) in the baking formula. The lower contents of lipids in bread possibly resulted from binding of some of the flour free lipids by wheat proteins as a result of gluten development during mixing and manipulation of the dough (Frazier 1983: Chakraborty and Khan 1988a). Thus, less free lipids were extractable by petroleum other which only extracts the free lipids. The comparison of bread composition with flour composition also showed that variation in bread protein contents among varieties (Table 28) follows the same trend found in their original flours (Table 5). The drop in TDF contents in bread (Table 29) was much higher (30‘ of that in the original flour) for Charmany and aillsdale breads, whereas only 10$ drop was found in Augusta bread. The average drop in TDF of all varieties after baking was 22‘. 163 60:30.30 .5 03030.00 20. 3.3.0.8. 030000500000 .003 o... 0. 0.8 o 50.000088 0050 50.0300 k. 0050:0000 0.5: 00.0.. 00.: 0 .300: 0.0.30 .33 of 0. no. 0 .0.0 x z 0 0.. 0.. 0.~ ~.0 0.~ 0.~ ~.~ 0.n m.0 0020 TR- 0.0L. 0.0L. 0.0L- T8- ..0... fit. TE- ~00- 08.0... m.00 0.n0 0... m.00 n.00 0.0m 0.». 0... ..00 50¢ 0.-- ...~- n..~- 0.0.- m.0~- 0..n- n.m~- 0.m~- ~.0~- 0.0. 0... 0.0. 0.0. 0... ~... 0.~— n.0. ..0 ..0. 00.00000 ouoto>< 0000000. 000000.000. 0000000 0.000...= >cautogu ..o:0.au 0.00:0 0:000 0000.0000 «00...: 0.3.0 no.0».to> 0.0;: «..:: 0.00 mo_uo_ta> anus: 00¢ ..om .50.. e.gtouofi c. 0005 5.: 8.020900“. 0. 000.5 05 .0 38.890“. 00.3: 0..» 5 0.0.3 00:05 0:09.00 0N 30¢. 164 A greater drop was found in bread lipid contents (averaged 75‘) from the original amount in the flour as a result of the breadmaking process (Table 29). Bread baked with Hillsdale flour showed the largest drop in lipids, whereas that made with Charmany flour had the least percent drop. Prediction Equations for Balady Bread Optimum Baking Water Absorption, and Mixing Time The stepwise regression procedure (SAS 1986) was used as a.mmdel building technique to develop mathematical equations that can be used to predict baking water absorption, and baking mixing time. Predictors were those measurements made on the eight soft winter wheat flours: Protein, total dietary fiber (TDF), lipid, total carbohydrate, damaged starch, and pentosan contents as well as AWRC t and AWRC g/g protein, and, the rheological measurements made on the flour-water doughs using the standard farinograph (Prg) and mixograph (ng) procedures, and the back extrusion test at three shear rates. The Instron is a very expensive machine and might not be available for some cereal technology laboratories, therefore, the stepwise»procedure was used twice for each dependant variable. In the first run, the back extrusion data collected using the Instron were included among other independent variables. In the second run, the instron data were excluded in order to get other useful prediction models that can be utilized under different conditions. In each run, predictors having F-statistic of a-O.5 or lower were introduced to the model one after another. A predictor stays in the model if its F-statistic is significant at a-O.2 or lower, otherwise it is removed. Although the stepwise procedure may provide a large number of useful and best fit models, only simple and efficient ones were selected. 165 1. Prediction of baking water absorption (WA) of Balady bread l.e. When the Instron data were included: The first candidate predictor was mixing tolerance index (MTI ) as measured by the standard Fro farinograph procedure. The one predictor model containing MTIml explains 75s of the variation in WA. The regression model is significant at a<0.006. Farinograph arrival time (ArrT) and flour protein content were the following predictors to be introduced into the model. The three predictor model is WA 8 60.0 - 0.08 III". - 4.46 "a". + 0.97 protein (1). The model explains 98.5t of the variation in WA and is significant at a<0.0004. Larger models were suggested by the stepwise procedure by incorporating additional predictors to model (1) . The contribution of these new predictors to the model was very small. Model (1) is recommended because of its simplicity and enough efficiency. Prediction of water absorption for baking Balady bread requires doing only two tests; the protein content and the farinograph. 1.b. When the Instron data were excluded: The best fit simple model was typical to Model (1) mentioned above. The stepwise procedure expanded the model to include mixograph dough stability, farinograph peak time, AWRC (%, 14$ m.b.), and AWRC (g/g protein) as additional predictors, however, model (1) was considered only for its simplicity. 2. Prediction of baking mixing time of Balady bread 2.a. When the Instron data were included: In a similar manner of developing the best fit model as mentioned above, the three predictor model that can be used to predict for baking mixing time (MxT) was found to be: m - 9.17 + 0.26 stability".- 0.16 aream+ 0.03 rag-op, (2). The model has R2 of 0.981 and a<0.00l. Dough stability as measured by the standard farinograph procedure accounts for 72$ of the variation in baking 166 mixing time among the eight flours while the mixograph area predicts an additional 20: of that variation. Only 6‘ of the variation is associated with the back extrusion percent drop in curve height after 30 sec from peak measured at the shear rate 3.24 sec". 2.b. When the Instron data were excluded: The best fit and simple prediction equation became M II 7.29 + 0.29 stability"..- 0.10 aream- 0.77 ArrT". (3). The model is significant at a-0.001 and explains 97.63 of the variation in mixing times used for baking Balady bread from the eight SWW flours. Farinograph stability, mixogram area, and farinograph arrival time associated with 72, 20, and 6% of the variation, respectively. Mixograph peak time was the following predictor to enter. The four predictor model is significant at 080.0003 and explains 99.8% of the variation in baking mixing times. The new model is: MxT 8 6.77 + 0.36 stability". - 0.08 area" - 0.71 hrrTfm - 0.22 peakti-em (4). Both models can be used and both require measurements made using the farinograph and mixograph tests. However, because mixograph peak time associated with only 2‘ of the variation in mixing time, Model (3) may be utilized in predicting mixing time without much loss in prediction efficiency. It can be concluded from these prediction equations that flour protein content associates with baking water absorption. Prediction of baking absorption requires measurements of farinograph arrival time and mixing tolerance index, and flour protein content. Mixing time for baking Balady bread can be predicted by using farinograph stability and mixograph area along with either percent drop in height of the back extrusion curve or dough arrival time of the farinograph. 167 Ultrastructure Study of Dough and Bread Systems Flour-water dough systems Ultrastructure of the flour-water doughs prepared with the eight SWW flours was studied using the scanning electron microscope (SEM). Micrographs of the freeze-fractured, freeze-dried dough samples are shown in Figures l7A-D and 18A-D. Inspection of all intact dough surfaces using the SEM showed the continuous veil-like pattern of the protein covering the dough surface. Such a patternxmasked any details regarding the dough interior. Therefore, these micrographs are not included in the dissertation. Fractured surfaces (Figures 17 and 18) revealed, however, that gluten proteins extended through out the dough mass in the form of both web-like (PW) and sheet-like (PS) structures. These two protein structures were evident for all the eight doughs, but in different proportions. Starch granules of various sizes were found evenly distributed and embedded within the protein matrix. Under the effect of fracturing the frozen doughs, some of the starch granules may be cleaved leaving portions of the granules which possess elliptical contours (Figures 173,C and 183). In other micrographs (Figures 170 and 180,0) some of the starch granules, particularly larger ones were completely dislodged from thermatrix leaving mantle- ”pock-" like locations, which were pointed to using arrows, within the matrix. The fractured starch granules showed solid interior structure (Figure 183). The contours of the cleaved granules were connected with the surrounding protein matrix with thread-like protein filaments indicating a possible interaction between the proteins and surface of starch granules (Figure 17C and 183). Micrographs of the doughs prepared with Adena (Figure 17A) and Hillsdale (Figure 18A) flours showed predominance of the sheet-like (PS) over the web-like (PW) protein structure. It is noticed from these two 168 Fig. 17. Micrographs of freeze fractured, freeze dried flour- water dough samples made from A, Adena: 3, Auburn: C, Caldwell; D, Charmany flours. Some of starch granules (s- intact; SF- fractured) are disclosed from the thick strand- (P8) or web-like (PW) protein network. Bar- 10 um. Arrows . A, protein filaments; B, the solid interior of cleaved starch granules; C, great affinity of the protein to the starch surface: 0, mantel-like locations where starch granules were dislodged. 170 Fig. 18. Micrographs of freeze fractured, freeze dried flour- water dough samples made from A, Hillsdale; 3, Augusta: C, Frankenmuth; D, Tecumseh flours. Some of starch granules (s- intact; SF- fractured) are disclosed from the thick strand- (P8) or web-like (PW) protein network. Bars 10 pm. “Arrows-.A, reticulated protein structure; 3, great affinity of the protein to the starch surface: C and D, mantel-like locations where starch granules were dislodged. 171 172 micrographs that protein strands in the dough made with the Hillsdale flour (Figure 18A) were discontinuous and generally had smooth edges. In contrast, the protein strands (P8) in the dough made from Adena flour (Figure 17A) were apparently continuous and had more filamentous "finger- like” projections which bridges among parted edges of the protein strands themselves and among the’protein thin layers covering the starch granules. Similar observations were reported by Lorimer et al (1991) for flour-water doughs prepared from a hard spring wheat flour. These observations may indicate the relatively more elastic property of proteins of the dough made with Adena flour in comparison with those of the dough made with Hillsdale flour. The web-like (PW), reticulated protein structure was also evident in the micrographs of the two doughs. The reticular pattern of the protein network has been reported for low-temperature-SBM micrographs of fractured dough surfaces (Berglund et al 1990, 1991: Lorimer et al 1991). Berglund et al (1991) attributed reticulation to the formation of ice crystals during thawing of frozen pan bread doughs. Freeman et a1 (1991) proved, however, that wheat gluten exhibited the reticular sponge-like structure in both the untreated fresh or frozen states. The SEM.micrograph of isolated wheat gluten reported by Belitz et a1 (1986) also showed the porous, web-like nature of the gluten network. The structural differences between the doughs prepared with Adena (Figure 17A) and Billsdale (Figure 18A) are in agreement with their rheological properties measured using the back-extrusion and mixograph tests. The dough prepared with the Adena flour had higher values of apparent elasticity and viscosity index in comparison with that made with Billsdale flour. Also, the higher value of the curve slope of the dough made with Adena flour, in comparison with that made with Hillsdale flour, indicated a relatively more coherent dough. Also, the standard AACC mixograph test indicated that the dough made with Adena flour was relatively stronger, i.e. having a larger value of curve area, and more 173 tolerant to overmixing, i.e. having a larger value of 8-min curve height, in comparison with that made with the Hillsdale f1our. Micrograph of the dough made with Caldwell f1our (Figure 17C) showed both the web-like (PW) and sheet-like (PS) structures of the protein matrix. The sheet-like structure took the form of strands that extended throughout the dough mass. These strands were solid in some areas and fibrous or filamentous in other areas. However, the web-like protein structure was the predominant and was extending from the surrounding protein strands. The web-like protein structure (PW) was also seen in. micrographs of the doughs made with Charmany (Figure 170), Frankenmuth (Figure 180), and Tecumseh (Figure 180) flours. Few areas of PS were also seen within these doughs (Figure 18 C,D). The protein matrix in the micrograph of Frankenmuth dough (Figure 18C) looked more discontinuous and showed more broken fragments which indicated a relatively weaker dough. These doughs, in comparison with those prepared with Auburn, Caldwell, and Augusta flours (Figures 17 B,C: 18 3), showed relatively fewer cleaved starch granules and some of thermantle-like locations within the protein network as the result of complete dislodging of the granules. The ease of dislodging of the granules may indicate a relatively looser binding between the granules and the protein network. In contrast, micrographs of the doughs made from Auburn (Figure 173), Caldwell (Figure 17C), and Augusta (Figure 183) flours showed, in comparison with those of the other doughs, more of the cleaved starch granules. This may indicate greater affinity and interaction between the protein and starch granules in the doughs made with flours of these three wheat varieties. Comparisons among these six varieties with respect to their dough rheological measurements made by using the standard AACC farinograph and mixograph procedures indicated similar properties with few exceptions. These exceptions were related to dough stability and tolerance to overmixing. Doughs made with the flours of Auburn and Tecumseh were 174 relatively more stable than those»of Frankenmuth and Charmany doughs. The dough made with Charmany flour was less tolerable to»overmixing and showed faster break down in comparison with Auburn and Tecumseh doughs. The dough made with the Frankenmuth flour also was less tolerable to overmixing than that of Auburn as was indicated.by higher farinograph MTI, and than that of Tecumseh as was indicated by lower mixograph 8-min curve height. The ability of dough proteins to withstand the increase in water content can be demonstrated from the comparison between Balady bread baking absorption and the farinograph absorption of the eight flours. Baking absorptions were determined subjectively according to the handling properties of the doughs. These absorptions were found to be higher than those measured by the standard farinograph. The percentage increase in absorption averaged 10.6% and showed a wide range of 7.1%-16.0%. Four of the six flours mentioned above, namely, Tecumseh, Auburn, Caldwell, and Augusta were at the upper side of the range and recorded 16.0, 14.9, 11.5, and 11.1% increase in absorption, respectively. This indicated more ability of their protein structure to support the increase in the water content of the dough. In contrast, flours of Frankenmuth and Charmany showed lower values of 7.14 and 8.3%, respectively which may indicate a relatively less ability of their protein structure to hold more water and still be able to possess satisfactory dough handling properties and to produce quality bread. Two observations that were made during preparation of doughs for baking Balady bread are noteworthy. First, dough prepared with Hillsdale flour was relatively more wet, weak, and sticky than the other doughs regardless of its lower water content in comparison with other doughs. Therefore, the dough made with Hillsdale flour needed special attention to avoid breakdown during flattening and manipulation steps. Secondly, the dough prepared with Augusta flour was more elastic and apparently'drier than the dough prepared with Hillsdale flour. The Augusta 17S flour dough also required special care during the flattening step as it did not respond easily to flattening, being so elastic it was returning to its previous diameter. The dough required slower hand strokes than the other doughs for flattening to achieve the desired dough diameter; On the microstructure level, fractured surface of Augusta dough indicated that the starch granules were firmly imbedded in the protein network. Upon fracturing the frozen dough, this firm binding reduced the number of dislodged granules in comparison with the cleaved ones. In contrast, protein strands of the dough made from Hillsdale flour looked weak, discontinuous and had smooth edges. Fractures in the dough made with Hillsdale flour occurred through the protein strands which may indicate a less coherent dough with increased ease of slippage between the protein layers. A previous study reported different fractionation patterns for the gluten proteins extracted from Augusta, Frankenmuth, Tecumseh, and Hillsdale flours (Zabik and Tipton 1989). In contrast to the gluten extracted from Augusta flour, gluten extracted from Hillsdale flour produced higher amounts of gliadin-rich and lower amounts glutenin-rich protein fractions. This finding indicated that gluten of Hillsdale was less viscous and less elastic than the gluten of Augusta. Extraction patterns of the gluten proteins of Tecumseh and Frankenmuth flours were intermediate to those of Hillsdale and Augusta gluten proteins. These facts confirm with the weak characteristics of protein structure of Hillsdale dough and the relatively highly elastic protein structure of Augusta dough. Doughs made of Frankenmuth and Tecumseh flours showed structure similar to that of Augusta dough, however, the web-like protein structure looked less continuous and fragmented in some areas. Also, a smaller number of cleaved starch granules and a larger number of dismantled granules were seen in the micrograph of Frankenmuth and Tecumseh doughs. 176 Balady bread systems Ultrastructure of Balady bread baked with the eight SWW flours was also studied using the SEM. Bread samples were examined as such or after the treatment with the iron containing compound: acetyl ferrocene. Micrographs of bread top and bottom surfaces and interior of the loaves were obtained using the secondary'electron (SB) and backscattered electron (BS) detectors of the SEM. Selected images were chosen and will be presented to show differences in the ultrastructure among and within the breads. There is no available information in the literature regarding the ultrastructure of Balady bread. In comparison with white pan bread, Balady bread is made with flours of higher extraction and is baked at higher temperature for shorter time. Balady dough contains higher water content and no added shortening or sugar. These differences in dough formulation and breadmaking process are expected to introduce differences in the ultrastructure between the two types of breads. Inspection of the Balady bread specimens indicated that the baking process has introduced extensive changes in the protein and starch structures previously described for the eight doughs. The web-like protein structure that was seen previously in the flour-water dough micrographs (Figures 17 and 18) has disappeared in those of the baked breads. The protein at the surface of the bread samples had a sheet-like structure which covered the starch granules. This sheet-like protein structure was continuous for some samples (Figure 193) and was discontinuous for others (Figure 19A,C). The ability of wheat proteins to form the strand-like structure increases after dough manipulation and proofing (Evans et al 1981). The protein sheet-like structure was the prominent in the doughs made from complete formula (Fretzdorff et al 1982). Khoo et al (1975), using the SEM, reported that proteins in baked 177 Fig. 19. SEM micrographs of top layers of untreated Balady breads made with A, Tecumseh; B, Hillsdale; C, Frankenmuth flours. Images were collected using the secondary electron detector. (Sc starch: P- protein: 3- gelatinized starch exudate). Bars 10 pm. Arrows- A, C folded and distorted starch granules; B, gelatinized starch exudate leached from a weak point in the surface. 179 breads changed little in their appearance in comparison with those in the dough. TEM studies of bread structure agreed with these SEM findings (Bechtel 1985). Electron micrograph of the exterior surface of the top layer of the bread made with Hillsdale flour (Figure 193) showed a dull surface which lacked details as the result of the presence of large areas of sheet-like protein structure covering the starch granules. Near the middle of Figure 193, some of soluble starch which had diffused from the granules, i.e. starch exudate (B) leached out through a crack in the surface. The starch granules did not show remarkable changes in their original contours and shapes which indicates their limited degree of gelatinization. In contrast, more advanced degrees of gelatinization were seen for some of the starch granules located on the exterior of the top layer of Tecumseh bread (Figure 19A) which looked distorted in shape and folded. This might be attributed to the relatively higher baking absorption of Tecumseh bread; 63% in comparison with 59% for Hillsdale bread. SEM micrographs of the exterior surface of the top layers of bread made-with Frankenmuth (Figure 19C) and Tecumseh (Figure 19A) flours showed a similar appearance. The protein at the surface looked disrupted and discontinuous. This may indicate that the protein layer was originally thin and more extensible. Starch granules in both images showed some evidence of gelatinization, i.e. they were distorted in shape. A higher degree of shape distortion and surface irregularity of starch granules of the exterior surface of top layers of these two types of bread in comparison with that of Hillsdale bread suggested a higher degree of starch gelatinization for the exterior of the top layers of these two breads. The limited starch.gelatinization and continuity of the protein layer covering the surface in the micrograph of the exterior of top layer of Hillsdale bread may explain the relatively tough texture and low acceptable scores of Hillsdale bread top layer. Sensory evaluation of the 180 baked breads has indicated that top layers of bread made with Tecumseh and Frankenmuth flours were equally acceptable and were significantly better than that of the bread made with Hillsdale f1our. Also, the puncture test indicated that top layer of Hillsdale bread, in comparison with that of Tecumseh bread, was relatively tougher and required a slightly higher puncture force (0.10>P>0.05). In most bread samples, the leached gelatinized starch fused with the protein structure forming layers of irregular shapes which masked the underlying details. Treatment with acetyl ferrocene was necessary to increase density of the sample and to improve its contrast. It also helped in revealing more sample details by washing out the leached soluble gelatinized starch which was coverihg the surface. Figure 20 shows SEM micrographs of the exterior surface of the top layers of breads made from Hillsdale (A) and Frankenmuth (B) flours and treated with acetyl ferrocene. Images were collected using the back- scattered electron detectors of the SEM. This detector provides information based on topography and electron density of the surface, whereas the secondary detector reflects information related to sample topography. The micrograph A (Figure 20) showed the compact structure of top layer exterior of bread made with Hillsdale flour in comparison with that of Frankenmuth bread (Figure 203). Micrographs of the bread made of Hillsdale flour (Figure 20A) showed limited shape deformation and surface irregularity of the starch granules which reflect their limited degree of gelatinization. The granules maintained their original conformation except for a few that showed slight surface irregularity. This is in agreement with has been observed in top surface of the untreated Hillsdale bread (Figure 193) which showed a limited degree of starch gelatinization. In contrast, the exterior of the top layer of the Frankenmuth bread treated with acetyl ferrocene (Figure 203) showed slightly more shape distortion and surface irregularity of starch granules 181 Fig. 20. SEM micrographs of top layers of Balady bread treated with Ferrocene. Samples were made with Hillsdale (A) and Frankenmuth (B) Flours. Images were collected using the Backscattered electron detector. (s- starch; P- protein). Bar- 10 um. Arrows- A, protein matrix having smooth edges; 3, folded and distorted starch granules. Numbers- 3, l- slightly swollen, 2-swollen, 3-expanded. (with. surface irregularity); B, 4- surface indented, 5- collapsed, 6- flexibly folded starch granules. 182 183 which reflected more advanced stages of gelatinization. Treatment of bread samples with acetyl ferrocene which included the submerging of the sample in buffered glutaraldehyde solution and dehydration with ethanol has introduced some artifacts (Figure 20A,B). These artifacts are denaturation and disruption of the proteins at the sample surface, washing’ out of 'the soluble» gelatinized starch, and loosening of starch granules from their locations in the protein matrix. However, more information becomes attainable after removing the leached gelatinized starch covering the surface. Given that bread samples had received the same treatment, comparison among them with regard to the remaining protein matrix may provide useful information. The exterior of the top layer of the Frankenmuth bread treated with acetyl ferrocene (Figure 203) indicated the filamentous nature of the remaining strands of the protein matrix at the surface. The starch granules in the bread.made with Hillsdale flour (Figure 20A) looked less loose and more confined within the protein matrix which had a smooth appearance. These differences in bread structure match those differences reported earlier for the structure of doughs of these two varieties. Figure 21A, 3 showed back-scattered electron micrographs of the exterior of the bottom layers of Frankenmuth and Adena breads treated with acetyl ferrocene. Both images indicated the expected disruption of the protein layer covering the starch granules as the result of chemical fixation. Exterior of the bottom layer of Adena bread (Figure 213) showed that the starch granules were more confined within the protein network. The later possessed strand-like structure in some parts of the image. These observations reflect stronger structure of bottom layer of Adena bread in comparison with that of bread made with Frankenmuth flour. Bottom layer of Adena bread received a lower sensory score and required more puncture force than that of Frankenmuth bread, however, the differences were not statistically significant. 184 Fig. 21. SEM micrographs of bottom layers of Balady bread treated with Ferrocene. Samples were made with A, Frankenmuth and B, Adena Flours. Images were collected using the Backscattered electron detector. (5- starch; P- protein). Barle pm. Arrows-B A, loose binding and 3, firm binding of starch granules within the protein matrix. 185 186 Starch granules in the exterior of the bottom layer of the baked bread appeared to pass through more stages of gelatinization than those of the corresponding top layer. This was evident from the micrographs of the exterior of top (Figure 20B) and of bottom (Figure 21A) layers of Frankenmuth bread that were treated with acetyl ferrocene. Evidence for' more advanced stages of gelatinization of starch granules can be seen in Figure 22A-C for micrographs of the inside of untreated bread made with Auburn, Charmany, and Caldwell flours. These micrographs showed a similar appearance. The leached gelatinized starch was completely fused with the protein matrix forming a new phase that is responsible for the waxy appearance of the crumb of the Balady bread. The Breads of these three varieties had similar sensory scores for bread chew and combined score. However, crumb of Caldwell bread (Figure 22C) looked a slightly more compact than that of Auburn (Figure 22A) or Charmany (Figure 223) bread. Pores of microscopic size were seen at surfaces of the protein-starch exudate phase in the bread crumb (Figure 22). These microscopic pores are not in the micrographs of exterior surfaces of the upper or lower layers of the bread. Pomeranz and Meyer (1984) reported also the presence of microscopic pores in the crumb of white pan bread. Evans et a1 (1981) showed also that the gluten surface in the flour-water doughs contained small pores of less than 1.5 pm in diameter and were thought to be locations of lipids or volatiles. Bechtel (1985) indicated that these vacuoles which were seen within the protein strands of the doughs and the breads at the early stages of baking, have disappeared by the end of baking. Micrographs of crumb of bread made with Hillsdale (Figure 23A,B) and Adena (Figure 23C,D) showed differences in the protein structure comparable with those observed in the micrographs of the flour-water doughs made with flours of these two wheat varieties (Figures 17A and 18A). The protein matrix looked smooth and continuous in the case of 187 Fig. 22. SEM micrograph of areas having highly gelatinized starch in the crumb of untreated Balady breads made with A, Auburn: B, Charmany; C, Caldwell flours. Bar- 10 pm. Arrows- ultramicroscopic pores within the surface of the new phase resulted from fusion of the gelatinized starch exudate' and the protein matrix. 188 189 Fig. 23. SEM micrograph of the interior of Balady bread treated with Ferrocene. Samples were made with A and B, Hillsdale; C and D, Adena flours. Images were collected using Secondary (A, C) and Backscattered (B, D) electron emission. (Sc starch; P- protein). Bar- 10 pm. Arrows= A, a flexibly folded gelatinized starch granule: B, smooth protein structure; C, filamentous protein structure. 190 191 Hillsdale crumb (Figure 23A,B), whereas it looked filamentous in the case of crumb of Adena bread. Starch granules in both micrographs showed various degrees of gelatinization, i.e. looked intact, distorted, folded, flexible, or collapsed. Crumb of Hillsdale bread showed, however, more of the intact, small starch granules. Bread made with Hillsdale flour received low sensory scores for its inside and chew characteristics by the panelists. It can be concluded from this study that the degree of gelatinization of starch granules vary depending on the location within the baked loaf. This is in agreement with the findings of Varriano-Marston et al (1980) who reported that the extent of gelatinization of starch granules in different location within a baked product followed the gradient of moisture distribution within that product. Shape deformation, elongation, swelling, and folding of the granules was maximum at the center of the baked product. The authors attributed the limited gelatinization and swelling of starch granules of the crust to the lower water availability as the result of water evaporation from the surface of the baked product. SUMMARY AND CONCLUSION The main objective of this study was to evaluate some Eastern soft winter wheat (SWW) varieties in their performance in baking Egyptian Balady’ bread. In order to achieve this objective, five soft red varieties- Adena, Auburn, Caldwell, Charmany, and Hillsdale and three soft white wheat varieties- Augusta, Frankenmuth, and Tecumseh were selected. The 90% extraction flours milled from these eight wheats were evaluated for their chemical composition, dough rheological properties, and Balady bread baking quality. The rheological studies were performed using the farinograph, mixograph, and back-extrusion techniques. The baked breads were evaluated subjectively for their acceptability, and objectively for their layer thickness, texture, and color. Linear regression analyses were performed in order to obtain mathematical equations that can be used to predict baking absorption and mixing time. Ultrastructure of the flour-water doughs and breads baked from these varieties were evaluated using the scanning electron microscope (SEM). Evaluation of the chemical composition of these eight flours indicated, on a dry weight basis (d.b.), a narrow range of protein (10.7- 11.7%), total dietary fiber (8.6-10.3%), ash (1.1-1.2%), lipid (l.7-2.0%), and total pentosan (2.9-3.4%) contents. Damaged starch contents of these eight flours were evaluated by the Soft Wheat Quality Lab. (SWQL) personnel, Wooster, OH and were found in a narrow range of 4.1-4.6% on 14% moisture basis (m.b.). Alkaline water retention capacity (AWRC) ranged from 61.0 to 64.8% (14% m.b.), and from 6.4 to 6.9 g/g protein. In comparison to flours of the white varieties, those of the red varieties 192 193 had generally higher AWRC% which may be related to their slightly higher contents of total dietary fibers. The standard AACC farinograph study indicated a narrow range»of water absorption (S4.3-56.5%) for the eight flours. All the flours had similar dough arrival times (1.0-1.5 min) and peak times (1.5-2.6 min). Auburn dough showed the highest stability; The stability time of both Auburn and Tecumseh doughs was significantly longer than that of the dough prepared with Hillsdale flour. Differences in stability among other doughs were not significant (P>0.05). Differences ianixing tolerance index and break down time among the doughs were similar to those found for the stability measurements. The standard AACC mixograph study showed a slightly wider range of 55.6-59.5% for water absorptions in comparison with those measured by the farinograph. Mixograph peak time varied significantly among some varieties and ranged from 1.4-3.5 min. The dough prepared with the Auburn flour showed longer peak time than those prepared from the other flours except Tecumseh and Frankenmuth. Peak time of the Tecumseh dough was also longer than those of Hillsdale and Charmany doughs. All the eight doughs showed similar peak height (3.3-4.0 MU; full scale-10 MU). Curve height at 8-min of mixing was in the range of 2.9-3.5 MU. The doughs of Tecumseh and Auburn had a similar 8-min curve height which was higher than that of the dough prepared with Hillsdale or Frankenmuth flour. Area under the mixograph curves was in the narrow range of 51.4-58.7 cmz. The dough prepared with the Hillsdale flour had a smaller mixograph area than those prepared with Auburn, Tecumseh, or Adena flours. Doughs of Tecumseh and Auburn had the highest values for dough stability. In contrast, the doughs prepared with Hillsdale, Charmany, and Adena showed the lowest stability values. Other comparisons were of lower magnitude. The farinograph study'of the»eight flour-water doughs at their baking water absorption levels (59-64%) indicated that doughs of Auburn, Tecumseh, and Caldwell had longer arrival, departure, and peak times than 194 Hillsdale and Frankenmuth doughs. The Hillsdale dough was of shorter stability than Tecumseh and Auburn doughs. Peak height was in the range of 282-374 Brabender units (BU). The ascending order of the eight varieties with respect to their dough peak height was Tecumseh < Auburn - Caldwell < Augusta < Adena < Frankenmuth < Charmany < Hillsdale. Peak height of the eight doughs followed the same order of their values of baking absorptions. The mixograph study of the eight doughs at their levels of baking water absorption showed that Tecumseh and Auburn doughs having the longest peak times. In contrast, the dough prepared with Hillsdale flour had the shortest peak time. Frankenmuth, Tecumseh, and Auburn doughs had similar peak height. The later two doughs had lower peak height than that of Augusta or Charmany dough. Doughs prepared with Auburn and Tecumseh flours also had ‘the smallest. mixograph areas of thel eight doughs. Differences among the other six doughs were not significant. The mixograph peak time negatively correlated (P<0.01) with curve area (r8- 0.87) and with peak height (rs-0.59). In addition, the mixograph peak time correlated (r-0.94, P<0.001) with the farinograph peak time. Also, the farinograph peak height was found in a positive correlation with mixograph peak height (r20.43, P<0.05). The effect of using fixed water absorption levels (60, 65, and 70%) on the rheological properties of the eight doughs was also studied using the mixograph. The eight flours responded differently to the change in water absorption as was indicated by a significant interaction between wheat type and water absorption level. Tecumseh and Auburn doughs required longer mixing time than other doughs. At all water absorption levels, Frankenmuth and Hillsdale doughs showed similar values of peak height which were lower than those of Adena and Tecumseh doughs. Also, Augusta dough had lower peak height than Tecumseh and Adena doughs at the three absorption levels. Area under the curve showed significant variation among the eight doughs at all water absorption levels. Differences in 195 area among varieties tended to increase as water absorption level was increased. Generally, as water absorption was increased, peak time increased, whereas peak height, area, and B-min curve height decreased. The Instron back-extrusion test was done at three shear rates (3.14, 6.27, and 9.41 sec") on the eight flour-water doughs at 65% water absorption. Significant variation among the eight doughs were found for all the back extrusion measurements except for dough relaxation time and percent drop in curve height after 30 sec from peak (Fdrop). Peak height, Fdrop, and area after 30 sec from the peak showed a significant interaction (P<0.25) between the two main treatments: wheat variety and shear rate. The interaction indicated that the eight doughs responded differently to the change in shear rate. Curve slope which has been used as an index for dough cohesiveness indicated that the dough prepared from the Adena flour was more cohesive than those of Hillsdale or Tecumseh. Other comparisons among doughs showed no statistically significant differences. At all the three shear rates, dough of Adena, Auburn, and Charmany had higher values of peak height than that of Hillsdale. The other doughs showed intermediate values of peak height. Average peak area, which reflects total work input stored by the dough, showed that the dough of Adena had higher values than the doughs of other varieties except Auburn. The dough of Auburn had similar peak area to that of Adena dough but was larger than that of the Hillsdale dough. Averages of the back extrusion curve height at 30 seconds after the peak increased significantly as shear rate was increased from 3.14 to 6.27 sec". However, at the shear rate 9.41 sec", they were dropped to intermediate values. Values of the Fdrop of the doughs made with Charmany and Tecumseh flours were higher originally and showed a larger decrease as shear rate was increased from 3.14 to 6.27 sec” than from 6.27 to 9.41 sec’fi. Fdrop of the other doughs showed mixed trends. Area of 30 sec after peak of the back extrusion curve generally increased as shear rate 196 was increased. However, the degree of increase varied among the eight doughs. Dough viscosity index showed a trend similar to that of peak area except for Caldwell dough which had significantly higher viscosity index value than that of Hillsdale dough. Dough viscosity index ranged from 761 poise for Hillsdale dough at 9.41 sec'1 shear rate to 2087 poise for Adena dough at 3.41 sec'1 shear rate. Dough apparent elasticity ranged from 2.8 Newton/cm2 for Caldwell dough to 7.6 Newton/cm2 for Adena dough at 3.14 sec“'. These values were in agreement with the published ranges for dough apparent viscosity and modulus of dough elasticity. Measurements of dough rheological properties using the back extrusion were found to be shear rate dependent. This was evident from the significant differences among the averages of the three shear rates and from the significant interaction. As shear rate was increased, averages of slope and of peak area increased, whereas averages of dough relaxation time and viscosity index decreased. Back extrusion measurements were correlated with those of the mixograph study made at 65% water absorption. Positive correlations were found between mixograph peak height and the back extrusion peak height, peak area, viscosity index, and apparent elasticity (r80.73, 0.71, 0.73; o<0.05, and 0.81: a<0.01, respectively). The mixograph B-min height was also in a positive correlation with the back extrusion averaged curve height at 30 sec after the peak and with Fdrop and curve area of 30 sec after the peak at the 3.14 sec'1 shear rate (r=0.79: a<0.02, 0.77; a<0.03, 0.81; a<0.01, respectively). Subjective evaluation of Balady breads prepared with the eight SWW flours included evaluation of the bread attributes: top and bottom layers, bread interior, aroma, taste, and mastication. All breads have received equally acceptable panelists' scores for all the’evaluated attributes with some exceptions. Top layer of Tecumseh or Frankenmuth breads was more acceptable than that of Caldwell bread. In addition, top layer of 197 Tecumseh bread was more acceptable than that of Hillsdale bread. Bottom layer of Augusta bread was more acceptable than that of Caldwell or Adena bread. Bread interior of Frankenmuth bread was more acceptable than that of Hillsdale bread. Bread aroma of Augusta or Frankenmuth was more acceptable than that of Auburn bread. Mastication characteristic of Augusta bread was more acceptable than that of Hillsdale bread. Hillsdale chew characteristics received a score that was less than acceptable. Bread quality index was calculated by summing scores of all attributes for each individual bread. Tecumseh, Augusta, or Frankenmuth bread, was of higher quality index than that of Hillsdale bread. In addition, bread of Tecumseh was of better quality than that of Caldwell. Objective evaluation of the breads included measurements of loaf thickness, texture, and color. No significant differences were found among breads regarding thickness of top (2.8-3.0 mm) or bottom (4.1-4.6 mm) layers. Bread Texture was evaluated using the Instron puncture test. The puncture curve was evaluated for peak height (puncture force) and total area under the curve. All bread showed similar values for puncture force and area of top or bottom layers with the exception that top layer of Tecumseh bread was softer than that of Hillsdale bread as it required less puncture force (0.10>P>0.05). Within each loaf, the bottom layer in comparison with the top layer showed slightly higher values of area under the puncture curve. However, both layers showed similar values of puncture force. Color measurements of the exterior surfaces of the eight breads showed significant variations. In general, the top and bottom crusts of breads made with flours of the white wheat varieties were lighter, less red, and more yellow in color than those of breads prepared with flours of the red wheat varieties. Generally, color of the bread bottom layers showed lower values for the degree of yellowness in comparison to those of the top layers, however, both layers had similar values for the degrees of lightness and redness. 198 Proximate analyses of the baked breads, in comparison with those of the original flours, indicated relatively higher protein and ash contents, and lower contents of lipids and total dietary fibers (TDF). The drop in TDF was large (30%) for Charmany and Hillsdale breads, whereas only 10% drop was found for Augusta bread. The drop in lipid contents which averaged 75% indicated the formation of a lipo-protein complex as a results of the breadmaking process. The bread baked with Hillsdale flour showed the largest drop in lipids, whereas that made with Charmany flour had the least percent drop. Linear regression analyses showed that farinograph mixing tolerance index, arrival time, and flour protein content associated with 98.5% (P<0.0004) of the variation in Balady bread baking absorption. About 98% of the variation in Balady dough mixing time among the eight varieties can be explained by the farinograph stability time and mixograph area in addition to the farinograph arrival time or the back-extrusion Fdrop (P<0.001) at 3.14 sec'1 shear rate. The SEM study of the freeze-fracture, freeze dried flour-water dough samples showed variation in their ultrastructure. Proteins in the dough samples formed a matrix that enveloped other dough components. The protein matrix was found in the form of both web-like (PW) and strand-like (PS) structures. The PS structure was found in abundance in the doughs made with Adena or Hillsdale flour, whereas the PW structure was prominent in the other doughs. The starch granules were seen in different sizes and shapes. They ranged from small spherical to large lentil-like granules of complete integrity. They were in even distribution within the protein matrix and were covered with a smooth layer of proteins. At the fractured dough surfaces, however, the granules were found either intact, cleaved, or completely dislodged from their embedded locations leaving mantle-like areas within the protein matrix. This reflected varying intensity of the interaction between the PS or PW protein structures and the starch surfaces. 199 The appearance of the P8 of the Adena dough, in comparison with that of the Hillsdale dough, reflected a relatively stronger structure which concurs with their mixograph and back extrusion rheological properties. Micrographs of the doughs made with Charmany, Frankenmuth, and Tecumseh flours, in comparison with those of Augusta, Caldwell, and Auburn dough, indicated. a relatively less coherent structure as the result of a relatively weaker interaction between the protein matrix and the embedded starch granules. The SEM study of bread samples revealed the expected changes in the protein and starch that took place during baking. Proteins in the bread samples were seen in an apparently discontinuous sheet- or strand-like structure. Most of the starch granules looked deformed and possessed various degrees of surface irregularity and shape distortion 'which reflected different stages of swelling and gelatinization. Soluble gelatinized starch which leached and defused out of the granules showed areas of irregular shapes which obscured sample details. Treatment of bread samples with acetyl ferrocene enhanced the image contrast and provided more insight to the bread structure and the morphology of the starch granules in particular. Inspection of the micrographs of bread samples indicated some differences in their ultrastructure. The exterior of the untreated top layer of Hillsdale bread, in comparison with that of Tecumseh or Frankenmuth bread, showed a more continuous protein structure covering the surface and less distorted starch granules i.e. a relatively a lower degree of gelatinization. This suggested a relatively more coherent and tougher structure of the Hillsdale bread top layer which is in agreement with the subjective and objective evaluations. The exterior surface of the acetyl ferrocene treated bottom layer of the Adena bread, in comparison with that of Frankenmuth bread, also suggested a relatively more coherent structure for the bottom layer of the Adena bread. These structural differences were also noticeable in the 200 micrographs of their doughs and were in agreement with the back extrusion measurements. Acetyl ferrocene treated crumb of the Hillsdale bread, in comparison with that of Adena bread, also reflected a relatively less degree of deformation and shape distortion of starch granules. This suggested a lower stage of gelatinization and tougher structure of the crumb of the Hillsdale bread. The Hillsdale bread received a slightly lower sensory score for its interior characteristics. In general, the degree of shape distortion and deformation of the starch granules was higher in the exterior surface of bread bottom layers than that of the top layers. This reflected a lower stage of gelatinization of the granules of the top layer of the loaf. In contrast, bread crumb showed the highest degree of distortion of the granules and the largest amount of leached gelatinized starch. This can be explained by the higher water availability for bread crumb and the fast water evaporation from the loaf surface. The conclusions of this study are as follows. Acceptable Balady bread can be baked from the 90% extraction flours of the soft winter wheat varieties. Bread prepared with Tecumseh, Frankenmuth, or Augusta flours was more acceptable than that made with Hillsdale flour. In addition, bread prepared with Frankenmuth flour was of better quality than that made with Caldwell flour. Although the eight flours showed nearly similar composition, their protein quality, water absorption capacity, and dough rheological properties contributed to the quality of the baked bread. Mathematical equations that were developed to predict for baking water absorption and mixing time emphasized the importance of flour protein content, water retention. capacity, and dough properties in controlling the bread making process. The SEM, which provided an ultrastructural view of the dough and bread, reflected differences in their structure that can be related to the rheological properties of the dough and panelist acceptability of the 201 baked bread. The SEM study emphasized the importance of flour proteins and water availability in affecting dough structure and bread quality. The back extrusion technique provided useful information regarding dough viscosity and apparent elasticity which are not attainable by the farinograph or the mixograph. Values of these two measurements were in agreement with those that has been reported using different instruments. Simple measurements of the back extrusion curve such as peak height also proved useful in prediction of Balady bread quality. RECOMMENDAIIONS FOR FUTURE 83883303 Food industries in Egypt are developing and growing rapidly. Developing new products or producing some of the traditionally popular products using large scale commercial process is of increasing interest. Large scale production demands necessary research to identify components and properties of the raw materials that control and attribute to the quality of these products. A research scheme similar to the one used in the current study can be used to acquire the necessary information. Balady bread production, storage and transportation to remote markets require intensive research in the areas of packaging and cereal technology. Studies for finding the appropriate package(s), dough conditioners, and antimicrobial agents are needed for the preservation of bread freshness and to delay microbial growth. As deep freezers became available, production and marketing of frozen Balady dough would be of great interest. Fractionation and reconstitution studies of different wheat flours are needed to identify the protein fractions that associate with Balady bread quality. Electrophoresis and High Performance Liquid Chromatographic techniques are also useful in providing such information. Further baking studies are needed to confirm with the protein fractionation studies. Wheat breading programs can then be designed to select for varieties that possess the appropriate pattern(s) of protein fractions. Blending of wheats of different properties prior to milling into flour also requires such knowledge. The back extrusion technique provided useful information regarding dough viscosity index and apparent elasticity. Its.measurements were found in significant correlations with the mixograph measurements. Basic and 202 203 applied research are needed for complete understanding the roles of level of water absorption, time of mixing and fermentation, and intensity of mixing or shear on controlling dough properties as measured by the back extrusion technique and how these properties can effect quality of the final baked product. The complicated, time dependent, viscoelastic property of the wheat dough deserves more extensive research. Research in the areas of food nutrition are highly recommended in order to solve some of the problems associated with malnutrition broadly known in the developing countries. These problems might be partially solved by supplementing or fortifying wheat flour with inexpensive flours or extracts rich in protein from non-wheat sources in order to increase the nutritive value of the widely consumed baked products such as Balady bread. Knowledge regarding proper formulation and suitable adjustments of the breadmaking technique are needed. Abboud, A. 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For example: the given score was quite acceptable .1.— J_ u ..L '_JS unacceptable acceptable excellent Upper layer (outside): Clean smooth surface, even shiny color with few brown spots; no odd particles, no burned or dry cracked surface. Bottom layer (outside): Clean with no uncooked flour particles; no odd particles, no burned surface, no cracks. Inside characteristics: Complete air-pocket formation. Crumb is soft and has open grain. Crumb is neither dense nor compact, but of least amount possible. Aroma: The sample smells acceptable and pleasant. TfiIt. 8 The sample tastes acceptable and pleasant; not acidic, bitter, salty, doughy, or yeasty. Mastication and chew: Bread is a little chewy, not soggy, crumbly, or rough; the mouth feeling is a little moist. 214 APPENDIX D Balady Bread Score Card Nu.: ......OOOOOOOOOOOOOO Date: ..........Time...... smpl. ’: ......CCOOOOOOOO Please read the instructions on the attached paper before you start and when needed. A. Upper layer (outside): _L ..I. ..L unacceptable acceptable excellent B. Bottom layer (outside): L _L .L unacceptable acceptable excellent C. Inside characteristics: .10 unacceptable acceptable excellent D. Aroma: unacceptable acceptable excellent E. Taste: unacceptable acceptable excellent F. Mastication and chew: _L ..L .L unacceptable acceptable excellent Comments: 215 .APPlnflDIx c: UCRIBS Approval of the Sensory Tests MICHIGAN STATE UNlVl-RSI I'Y I'mwaslfi counmu ON "Slum u Ixuuxm. Lu! I nun. . uICNIGAN - «ms-less HI‘IAN SUIIICTS :UCRIMSD m AOMUNBTIADON 80le m') ”was June 2, 1987 Mr. Samir R. Rabis Food Science 6 Human Nutrition Dear Mr. Rabie: Subject: Proposal Entitled, "Eastern U.S. Soft Wheat in Egyptian Balady Bread-Making: Performance and Acceptabilisz" UCRIHS' review of the above referenced project has now been completed. I am pleased to advise that the rights and welfare of the human subjects appear to be adequately protected and the Committee, therefore, approved this project at its meeting on June 1, 1987. You are reminded that UCRIHS approval is valid for one calendar year. If you plan to continue this project beyond one year, please make provisions for obtaining appropriate UCRIHS approval prior to June 1, 1988. Any changes in procedures involving human subjects must be reviewed by the UCRIHS prior to initiation of the change. UCRIBS must also be notified promptly of any problems (unexpected side effects, complaints, etc.) involving human subjects during the course of the work. Thank you for bringing this project to our attention. If we can be of any future help, please do not hesitate to let us know. Sincerely, L.— Benry E. Bredeck, Ph.D. Chairman, UCRIHS BEB/jms cc: Dr. Mary E. Zabik MSL' u as Allis—sun Act-ethos! We Imam-use APPENDIX D 216 APPENDIX D Analyses of Variance and Simple Correlation Tables .>H0>Huommmmu .Hoo.o 0:0 .Ho.o .mo.ovm um ucooeuwsofiu monomer «as .00 .0 .mouoovm :00: n m: o .aoooouu mo mooumoo n mm o ..Numouoofiaaou .mnuuooazv me n z o ..oummuoo«aamu .mumuoonzv an n z a ..numouooHHQou .mumuoozzv on n z 0 Nfi0.0 w wwco.o CH mcoo.o 0H Onh.o vN ado.o CH HOHHN «Hwo.o b eeeomo.o h seemvco.o h hem.H h «secon.o b ummnz m: ho m: mo m: an m: be 0m: Chm TOHSOm ozoucum osmosoo omofimeq comm name oneououm cououm 0000309 0:0 .moequ .:m< ..moe. Hosea aucumfio deuce .cwououm no mucoucoo pecan now cmwmoo oouwaoocom aaouoameoo noocoeuo> mo mom>~0c< on mamas 217 .>H0>Huooamou .Hoo.o 0:0 .Ho.o .mo.ov0 00 000000.0000 0000000 ... ... .. .uouoovm :00: n m: o .aoooouu mo mooummo u no o ..vuAuxooan umuoofiaaou .mnmnoonzv an n z n .05H0> ocfimmwfi moo ..vHAmeOan. mouoowamou .muuuooszv mm H z 0 oNN.o Hm eao.o om mmm.o om uouum aaaamn.n n mno.o m «00¢.m m mXUOHm moa.o b «aeNnH.o b «asnfio.b 5 “00:3 at no m2 mo om: one monoom ..0.0 .00 .:.00000 0\0. 1.0.5 we. ..0 nucououcmm Hence oum3< mouse ucwucoo conoucom Houoe 0:0 .0m34. xuwooono cofiucouom wove: ocwaoxa< Hoon ecu seamen xOOHm ouoamaoo neocowum> mo momaaocc Hm Manda 218 .mfiwu c300 xcoum xmocw mucoumaou mcwxflz ..09H0> mowmmfia 0:0 .muuoDMOwHQom “mumuoosz .ma n z. aooooum no momuoom ...0>.0000000 .Hoo.o 0:0 .so.o .mo.ov0 00 0000.0.0000 0000000 ... ... B H ~k. c: .092... oJQCVU me.o mm Hmo.o Nom.o moh.o woo.o meo.o h HOHHM cacmo.ma «aaoaaa «ovv.o «canma.m «ccemm.m mmo.o «stemm.o n #00:: 090m 0H9: mafia mafiafinoum mafia mafia sawumuomnd aha mouoom room ousuuomoo H0>wuu< nouns omouoovm :00: Awesomooum coca ouoocoumv mucoamuomoo: naoumocHuom How daemon ooNfiaoocom haouoansou neocofiuo> mo momaaoc< NM mflm<8 219 .Amummumofiaamm “mumumwnz “ma u 2V aoummum mo mmmummo u no a .>Hm>fiuommmmu .Hoo.o can .Ho.o .mo.ovm um unmofluficmfim mmuocmc ««« .«4 .« a mmc.o nab.a moo.o mvo.o weo.o m uouum «fitomo.m «hoH.OH «««mmo.o ~mo.o «taavm.o h ummnz wuwawnmum mwud mmascfiz Hanan unmflm: mafia aha wuuaom um panama xmmm xamm mmmumavm cam: Amuaomooum UU<< cumocmumv mpcmamuzmmwz samumoxw: you sawmma umnwsoocmm hamumaaaoo Imocmflum> mo mmm>HMC< mm mamaa 220 .AnummumoHHQom “unnumonz m¢~ u zv aocmmuu uo ammuomn n an n .>Hm>fluomammu .Hco.o can .Ho.o .mo.ovm um unmofluficvwm mmuocmc a¢¢ .«a .« m m.m~ w.m mo.o wm.o m¢.o mo.o ma uouum «¢«¢.hhma «ttm.wmmn «14om.¢ «ttmh.oa «««>m.mn «ttmw.b h ummnz mmuacfiz OH unmfimx mafia agwafinmum mafia mafia aha mouaom um unmwmx m>uzo xmwm muzuuwmmo Hm>fihhd ummumsvm cum: Anewuauomnd umumz ocfixmm u mo mmmaamcd vm wand? 221 .Amnmmumofiammm «mumumwsz “cm u 2v Ecummuu mo mwmuvmo n he a .>Hm>wuomamou .Hoo.o can .Ho.o .mo.ovm #0 “CMOqucmwm mwuocmc «1* .«t .c m mo.a moc.o mmoo.o me.o ma uouum «c«mm.~m «««¢m¢o.o «c«HNmo.o «««Hh¢.h h umm£3 mmu< mwuscfiz unvfiu unvflmm mafia nmo muuzom um uaofim: xmmm xmmm mmmumzvm cam: Anewunuomn¢ Hmumz mcfixmm adv mucmfiwusmmmz namumoxfl: Mom sawmoo vmnwaovcmm aaoumamaoo ImOCMMuw> no mmmxamca mm mamas 222 .Amummuwofiaqmm “numGOMHQHOmn4 “mumummnz «aw u zv soommuu mo mwmumma u an n .>Hm>«uomqmmu .Hoo.o can .Ho.o .mo.ovm um ucmofluficmfim muocmu ««« ... .« a nnm.m ¢oo.o ~oo.o mHH.o ma mm Hasnfimmm «mmm.ma «amdo.o «moo.o ¢««Hn~.a wa 4 x z *ttmom.mom ««#moe.o «««>¢m.o «««oam.mm N < .cofiunuomn< nnd.a ~oo.o Hoo.o mmv.o m Hm .3\mmom ««*oee.mh «.«amo.o «.«nmo.o «««>n¢.aa h 3 .ummnz omud amaze“: unmfim unoflmm mafia nun mousom um panama xmmm xmwm ammumavm cam: :ofiunuomnd amass «on can .mw .om um mucmamusmmwz nmmuooxfiz How cofimma Umuwaoncmm hamumamfiou Iwocmwum> no wwm>amc< mm mam<9 2123 ..Nuuo.nun¢n:m u~uaouou_.au¢ ununouog gnogm nouuuooga "no a av eunuch. *0 nooguoa u to n .>.o>_uuoauog .poo.o ace .Po.o .mo.ova an acoum»mcn.n «vacant «cc .cc .a o 00m.~ pmswn neo.o o—— c.5m no.0 «we oo.n o-.o co ~m .Lo uo.ooa «no.~ onoen neo.c o~P s.on 00.: o~m pn.e op.o no u ..:umnoa noc.~ oo—o~ m~o.o as e.on 06.0 con oo.~ pp.c o. m x axe soc.~ oamun o~c.c coq~ c.—n oo.a nnv o¢.m 59.: v. m x : .cmhm.np éNWN «5‘0 ...—.3: «cac.~8— cmnfi CCCNnNMm 21.3.08 cccmod N w 0»... ...-03m oos.p gosmn pno.o oc~ o.on mn.p mac «0.x e—.o a 3x: .3xoaoc ..ncm . mp CCCSO F No nno . o caquN k . 3p .5 wk . or ccaconcw cccvn . .3— c’ho . O N 3 . 900.5 >u.o_uao.m x0uc. ul_p anon tag» can ugu_ox soon 10;» can nogc u;o_oz ono.m ago ougaom “Egan... 3.88; 8:333. on ,6 8.2 5 83 on .- 222. goo. ...: amok-sum coo: moans goosm 005:» an cunningaaoo: co_naguxw soon so» co_ooa uo.a updam .oucamuo> mo uon>.oc< kn wan

Hm>«uowmmwu .Hoo.o can .Ho.o .mo.ovm um unmoHuwcmam mmuocmo «44 .«« .« .mmuwsvm cam: u m: .Eoummuu mo mmmuvmn n ma w .Amumwumowammu «mumummszv ma n z n .Annmmumofiamuu “wumummnxv «N n z m mmmo.o m." 250.0 m H¢bm.o ma mh¢a.o ma “Chum NHHo.o b «*«weoo.o b Hovh.o n a¢5m~>.o b Hams: m2 ma m2 mm m: an mum: Uho mouaom amcfimfiq nnm< «may mcfimuoum mafiafiq can .sm< .Amoe. umnfim mumumfio Hopes .cflmuoum no mucoucoo ommum How cmfimmo UmNfiEoocmm wamumamaoo Imocmwum> no m0m>am¢< mm qudfi 225 .>Hw>fiuomammu .Hoo.o can .Ho.o .mo.ovm um unmofiuficmfim mmuocmc *«¢ .«¢ .4 .aoommuu mo mmmummo u no n .Amumwamama m can .AmxooHn mumamaoov mmumoflanmu b .mumma3 my man u z m Hm.~ mm.H ¢¢.H mm.n o~.~ no.n cam Houum ¢H.n «*«mm.¢ «c*am.n vm.n «#«nm.¢ «tom.m mm m x 3 mH.n «o~.n ««om.~ o~.m «tHH.¢ awd.m an m x m a««om.nn «fi1hd.¢ba «#«mm.woa «#«mm.~n «*cmm.mh «*«oa.om m m mumfidmcmm «wm.n ««m~.n ~m.a «mw.m mH.n «Hm.v we 3 x m 0H.m mo.n «n«mn.m «mw.a «4Nm.o «#«Hm.oa h 3 mvmwn3 vo.~ ¢N~.v «om.n o~.m «avm.h hm.m m m mmumuHammm 30:0 mamas mfioud mufimcH um>mq “mama aha amousom ommum Eouuom mos mmumavm cam: coaumaam>m Ummum annamm no mmuoow .mumwamcmm you cmwmmn xoon mumamaou Imocmfiuw> mo mmm>HMC< mm mqmflfi 226 .>Hm>wuommmmu .Hoo.o can .Ho.o .mo.ovm an unmofiuficmfim mwuocmu .«« can ... .« .Amumwawcma m can ..xooan\munonz ¢V mxooan «H .mummcz my man u z a . mm.on can uouum *««mo.dm mm mx3 aa~>.aw mm mum «mn.~> ma m ..wuwmxoon «««mn.mmo~ m m .mumfiamcmm atto>.bwd h 3 ..ncmmummn3 mwumafim flaw: EOfimGHh mmUHSOm no mwmuomo Ummum >OmHmm mo mmuoom 00CMQEOU auomcwm Mom cowmmo xOOHm mumanaoocH uwocmHmm Imocmwum> no mamaamc< O¢ mam«uomnmmu .Hoo.o van .Ho.o .mo.ovm um ucmofiuflcvfim mmuocmo «a: can .4; .« .Amus> onwmmfia 0:0 .Amxooan mmumofiammu h .mummsz my mm n 2 H wmn.o mw~.n nom.a He uouum mam.o oma.h noe.~ o mmumowammm «««mam.¢ «¢«m¢¢.~m «atmom.db h mummn3 mumxma aouuom mumamH Eouuom muwqu Q09 accomum Hmouaom no llllllllllllllllllllllllll uo mmmumwo mmaam> a mmzam> A moumavm cam: mumhma aouuom Ummum mo mwaam> a van mumhmq Eouuom can 909 cmoum no mmaam> A no mucmswuammma HoHou no cvfimma xoon mumHQEou Imocmfium> no mfim>HMC< He Nance 228 .>Hm>«uommmmu .Hoo.o can .Ho.o .mo.ovm um ucmofiuficofim mmuocmc ««« can .«* .« .Amaam> ocwmmwa 0:0 .AxooHn\mummn3 ¢v mxoon «H .mumws3 av mm H z a mmH.o wha.o bba.o em HOHHQ xooHnmuucH ««e>m.o «.«moo.o «««m~m.o ma .fluaxooam c«¢mmm.m a¢«~N¢.m «itmmm.h h .ncmumwn3 mumama Eouuom mumxmq nos mum>mq mos Eoommum Hwouzom IIIIIIIIIIIIIIIIIIIIIIIIII no mo mmmuomo mmaaw> n mmsam> m mmumavm cum: mumhmq Bouuom vmmum mo mmnam> n flaw mumamq Q09 vmmum mo mmSHm> n vcm a mo mucwewuammmz uoaoo no cmwmmo xoon mumaaaoocH vmocmamm Imocmwum> mo mamaamc< «v mam<9 .>Hm>fiuommmmu .Hoo.o can .Ho.o .mo.ovm um unmowmwcmwm mmuocmo «¢« can .a« .« .Axooan uma mamas: v .mxooam «H .mumwn3 my om u z m om¢.nH h¢H.H onN.o hHH.w Hmm.o ¢mo.o mm HOHHH xooHnmuucH .5 263.3 mafia ~36 «323.3 .684 «53.0 3 ..nomxooam 2 www.ma oen.H mm~.o www.ma ~om.a ono.o h .«umuamnz mwud munch mmmcxofina mmud munch mmmcxofina Eovmwum amouaom IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII no mmmuomo umamq Eouuom Hm>mq QOB mmumzvm cam: mumhmq Eouuom can mos ommum homamm mo mmu< can .wouom musuocsm mmmcxofiza mo :mwmoo xoon mumaaaoocH vwocmem Imocmfium> no mam>HMC4 nv Nflm<8 230 ..:-9:9. n .— 33.} o n o~ a a 28...... .2... ......x. ... 3...... .. 823:2... ... .2... ..m... 2.3.2:... .9. u. ......33 9. E 328...: 530......3 0..-... < - .. 2...... ...--.: ... 8... . 2...... ...... ... «...... .. 3.... o 8.: ..:. ... ...... 2.. n... . 3.... . 3:33. ... .... .... .... .... 8.... .. 8.... o 8.: 95...... .... ...... .... ...... ... ...... .... .....- 2.. 3.... .. I... ..:... .1335... 2.. ~..... ... ...... ... .....- ... ...... .... fl... .. ...... e .3... ...-.-: 2. .... 2. ...... 2. 3.... 2. 8...- 2. ...... 2. 2.... 2. S... ... 2...... 5...... ... 3... ... ...... ... 3.... 2... 3.... ... ...... .2. 3.... . n... 2. an... ... 2...... .3. .. ...... 2. 2.... 2.. .....- ... .... ... ~.... ... ...... ... ...... ... .....- .. 3... . I... .3. 59.02:: u n v m o s o o ..— . ..:-...... 2...... ...... 2...... ....-. no... 8.. ..:... ...... 83...... 5:3... ...... .3. 2...... .8. 2...... ...-.... 33...... 33...... £933.... 9.3-(...... .1930... .1 to... £8... 9......- ... ...->0. 5.3.3.: .35 a... a. 90...: .53.. 3.3.30: «.23 ..0-...: :3 :33 .5 .... 230...... .1939...- 93 .1335... 5030. «282......3 333 cc 3.: 231 TABLE 45 Simple Correlationa Between Sensory Score Parameters for Egyptian Balady Bread Bread Characteristics Y6 Y5 Y4 Y3 Y2 Top Layer Y1 0.45** 0.28* O.36** 0.58** 0.63** Bottom Layer Y2 0.44** O.34** 0.52** 0.40** Inside Y3 0.44** O.63** 0.59** Aroma Y4 0.50** 0.65** Taste Y5 0.50** Chew Y6 Number of observations used for the calculations 8 56. Level of significence is indicated as follows: *, P<0.05; **' p