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C(w ‘V _L\__."'.' . . 1 ' - f .' ~ 'R' '.. firm 9, J. gift-ff; . “t‘vr-VLéM'ML‘y.’ -~ _, . _ " t .‘ - " “2‘14 fir} .~r 9 a 4 £— " . 5' ;.‘;'-‘.[.-.~_.;' ‘ ' -' - 7:“ 5 W) ,3 '} ‘4"- 1 . “my ,‘128'Mf5 Q WWWWWWWWW WW WWWW WW WWW V THY-791‘s 3 1293 301088 8182 r: #135 -‘ $35,: 53.3%?! {3.3“ {Eta} {)agw62521y W This is to certify that the thesis entitled PHYSICAL AND CHEMICAL CHANGES DURING PREPARATION AND COOKING OF DRY EDIBLE BEANS presented by Araya Tittiranonda has been accepted towards fulfillment of the requirements for M . S . degree inFood Science ///// 1250/M/5 Major professor Date a”; 2v‘v 7'5???” 0763‘.) MSU is an Affirmative Action/Equal Opportunity Institution MSU LIBRARIES RETURNING MATERIALS: Place in book drop to remove this checkout from your record. FINES will be charged if book is returned after the date stamped below. PHYSICAL AND CHEMICAL CHANGES DURING PREPARATION AND COOKING OF DRY EDIBLE BEANS BY Araya Tittiranonda A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Food Science and Human Nutrition 1984 ABSTRACT PHYSICAL AND CHEMICAL CHANGES DURING PREPARATION AND COOKING OF DRY EDIBLE BEANS BY Araya Tittiranonda The effects of soaking and cooking treatments as well as cooking temperature on physical and chemical characteris- tics of navy and kidney beans were investigated in two studies. Study I evaluated soaking methods (hot soak, two minutes boiled and one hour held; cold soak, 2 to 16 hours at room temperature) and cooking at 190 °F (87.8 °C). Hot- soaking resulted in greater chemical changes than cold- soaking. Hot-soaked and cooked beans were generally softer than corresponding cold-soaked beans. Beans became softer as the cook time increased. Greater losses of solids, ash, minerals, and sugars occurred during cooking than during soaking. Protein contents did not show significant changes. Study II evaluated four cooking temperatures 181.3 OF: 190.7 0F, 200.0 0F, and 207.5 0F (82.9 °C, 88.1 0C, 93.3 0C, and 97.5 °C). The effects of soak time and cook time were also considered. Elevated temperatures as well as prolonged soaking and cooking produced softer beans and a greater loss of solids from beans into the cook water. To Daddy, Mommy, Grandmas, Uncle, On, and Dhanes ii ACKNOWLEDGMENTS Grateful acknowledgment is extended to Dr. Mark A. Uebersax, my major professor, for his guidance and advices during my graduate study. Appreciation also goes to Drs. G.L. Hosfield, P. Markakis, and M.E. Zabik for serving as members of the committee. Special gratitude and appreciation are due to my parents, who gave me this opportunity for studying as well as continuing love, understanding, and encouragement. I am also grateful to my grandmothers, uncle, and sister for their support and thoughtfulness. Above all, my deepest gratitude goes to Dhanes, whose constant loving care, guidance, encouragement, and assistance made the accomplishment of this research project possible. iii TABLE OF CONTENTS LIST OF TABLES O O O O O O O O O O O O O O O O 0 LIST OF FIGURES O O O O O O O O O O 0 INTRODUCTION 0 O O O O O O O O O O O O O O O O 0 REVIEW OF LITERATURE . . . . . . . . . . . . . . Dry Bean Composition . . . . . . . . . . . . Seed Composition . . . . . . . . . . . Seed Coat . . . . . . . . . . . . Cotyledon . . . . . . . . . . . . Protein Content . . . . . . . . . . . . ‘ Ash and Minerals . . . . . . . . . . . Bean MATERIALS Carbohydrates . . . . . . . . . . . . . Preparation . . . . . . . . . . . . . . Soaking . . . . . . . . . . . . . . . . Cooking and Processing . . . . . . . . AND METHODS O O O O O O O O O O O O O 0 Material Preparations . . . . . . . . . . . MOiSture O O O O O O O 0 O 0 O O O Soaking and Cooking . . . . . . . . . . Blancher Cooking . . . . . . . . . Kettle Cooking . . . . . . . . . . Temperature Variation Cooking . . Methods of Analysis . . . . . . . . . . . . Texture . . . . . . . . . . . . . . . . Hydration Ratio . . . . . . . . Total Solids in Soaked and Cooked Beans Total Solids in Soak and Cook Waters . Ash Determination . . . . . . . . . . . iv Page vi viii w NO‘U' ow U 15 19 25 25 25 26 26 28 29 29 29 30 32 32 32 Protein Determination . . . . . . . . . . Mineral Analysis . . . . . . . . . . . Equipment Handling . . . . . . . . . Sample Preparation . . . . . . . . . Sugar Analysis . . . . . . . . . . . . . Statistical Analysis . . . . . . . . . RESULTS AND DISCUSSION . . . . . . . . . . . . . . Physical and Chemical Changes During Preparation of Beans . . . . . . . . . . . . Blancher Cooking . . . . . . . . . . Hydration Ratio . . . . . Total Solids in Soake and Cooked Beans . . . . . . . . . Total Solids in Soak and Cook Waters . . . Shear Force . . . Protein Content . Ash and Minerals Sugars . . . . . Kettle Cooking . . . . . . . . . . . Shear Force . . . . . . . . . . Protein Content . . . . . . . . Ash and Minerals . . . . . . . Cooking Temperature Effect on Physical Characteristics of Beans . . . . . . . . SUMMARY AND CONCLUSIONS 0 O O O O O O O O O O O O 0 APPENDIX 0 O 0 O O O O O O O O O O O O O O O O O 0 Calculation of Soak and Cook Water Preparation LIST OF REFERENCES 0 O O O O O O O O O O O O O O O Page 33 33 33 34 35 37 39 40 40 40 47 47 52 52 57 86 94 94 94 101 109 127 129 129 130 Table 1. 10. ll. 12. 13. 14. LIST OF TABLES Page Contents of selected minerals of raw, mature Phaseolus vulgaris classes . . . . . . . . . . . 7 Contents of selected minerals of raw and cooked Phaseolus vulgaris classes . . . . . . . . . . . 9 Physical and chemical changes during preparation of navy beans . . . . . . . . . . . . . . . . . . 43 Physical and chemical changes during preparation of kidney beans . . . . . . . . . . . . . . . . . 44 Analysis of variance for physical and chemical changes during preparation of navy beans . . . . 45 Analysis of variance for physical and chemical changes during preparation of kidney beans . . . 46 Changes of mineral content during preparation Of navy beans 0 O O O O O O O O O O O O O O O O O 61 Changes of mineral content during preparation of kidney beans . . . . . . . . . . . . . . . . . 62 Analysis of variance for changes of mineral content during preparation of navy beans . . . . 65 Analysis of variance for changes of mineral content during preparation of kidney beans . . . 66 Changes of sugar content during preparation of navy beans . . . . . . . . . . . . . . . . . . . 87 Changes of sugar content during preparation of kidney beans . . . . . . . . . . . . . . . . . . 88 Physical and chemical changes during preparation of navy beans . . . . . . . . . . . . . . . . . . 95 Physical and chemical changes during preparation of kidney beans . . . . . . . . . . . . . . . . . 96 Vi Table 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. Analysis of variance for physical and chemical changes during preparation of navy beans . Analysis of variance for physical and chemical changes during preparation of kidney beans . Changes of mineral content during preparation Of navy beans 0 O O O O O O O O O O O O O I 0 Changes of mineral content during preparation Of kidney beans 0 O O O O O O O O O O O C O 0 Analysis of variance for changes of mineral content during preparation of navy beans . . Analysis of variance for changes of mineral content during preparation of kidney beans . Effect of cooking temperature on physical characteristics of navy beans . . . . . . . . Effect of cooking temperature on physical characteristics of kidney beans . . . . . . . Analysis of variance for physical changes during preparation of navy beans . . . . . . Analysis of variance for physical changes during preparation of kidney beans . . . . . Z-values of navy beans . . . . . . . . . . . z-Values Of kidney beans 0 o o o o o o o o 0 vii Page 97 98 104 105 106 107 110 111 112 113 124 125 Figure 10. ll. 12. 13. LIST OF FIGURES Typical Kramer shear peak for bean texture evaluation 0 O O O O O O O O O O O O O O O O I Sample preparation for sugar analysis by High Performance Liquid Chromatography . . . . Changes of hydration ratio during preparation of navy beans . . . . . . . . . . . . . . . . Changes of hydration ratio during preparation of kidney beans . . . . . . . . . . . . . . . . Changes of total solids in soaked and cooked navy beans during preparation (Initial total SOlidS = 84.44%) 0 o o o o o o o o o o o 0 Changes of total solids in soaked and cooked kidney beans during preparation (Initial total SOIidS = 83.21%) C C O O O O O O O O O O C O 0 Changes of total solids in soak and cook waters during preparation of navy beans . . . . . . . Changes of total solids in soak and cook waters during preparation of kidney beans . . . . . . Changes of shear force during preparation of navy beans . . . . . . . . . .‘. . . . . . . . Changes of shear force during preparation of kidney beans 0 O O O O O O O O O O O O O O O 0 Changes of protein content during preparation Of navy beans 0 O O O O O O O O I O O I O O O 0 Changes of protein content during preparation of kidney beans . . . . . . . . . . . . . . . . Changes of ash content during preparation of navy beans . . . . . . . . . . . . . . . . . viii Page 31 36 41 42 48 49 50 51 53 54 55 S6 58 Figure Page 14. Changes of ash content during preparation of kidney beans . . . . . . . . . . . . . . . . . . 59 15. Changes of calcium content during preparation of navy beans . . . . . . . . . . . . . . . . . . 63 16. Changes of calcium content during preparation Of kidney beans 0 O O O O O O O O O C O O I O O O 64 17. Changes of copper content during preparation of navy beans . . . . . . . . . . . . . . . . . . 67 18. Changes of copper content during preparation of kidney beans . . . . . . . . . . . . . . . . . 68 19. Changes of iron content during preparation Of navy beans 0 I O O O O O O O O O O O O O O O O 69 20. Changes of iron content during preparation of kidney beans . . . . . . . . . . . . . . . . . 70 21. Changes of magnesium content during preparation Of navy beans 0 O O O O O O O O O O O O O I O O O 72 22. Changes of magnesium content during preparation of kidney beans . . . . . . . . . . . . . . . . . 73 23. Changes of manganese content during preparation of navy beans . . . . . . . . . . . . . . . . . . 74 24. Changes of manganese content during preparation Of kidney beans 0 O O O O O O O O O O O O O O O O 75 25. Changes of sodium content during preparation Of navy beans I O O O O O O O O O O O O O O O O O 76 26. Changes of sodium content during preparation Of kidney beans 0 O O O O O I O O I O O O O O O O 77 27. Changes of phosphorus content during preparation of navy beans . . . . . . . . . . . . . . . . . . 79 28. Changes of phosphorus content during preparation Of kidney beans 0 O O O O O O I O I O O O O O O O 80 29. Changes of zinc content during preparation Of navy beans 0 O O I O O O O O O I I O O O O O O 81 30. Changes of zinc content during preparation Of kidney beans 0 O O O O O O O O I O O O O O 0 O 82 ix Figure Page 31. Changes of potassium content during preparation of navy beans . . . . . . . . . . . . . . . . . . 83 32. Changes of potassium content during preparation of kidney beans . . . . O O O O O O O O O O O O 0 84 33. Changes of sugar content during cold soak preparation of navy beans . . . . . . . . . . . . 89 34. Changes of sugar content during cold soak preparation of kidney beans . . . . . . . . . . . 90 35. Changes of sugar content during hot soak preparation of navy beans . . . . . . . . . . . . 91 36. Changes of sugar content during hot soak preparation of kidney beans . . . . . . . . . . . 92 37. Changes of shear force during preparation Of navy beans I O C O O O O O O O O O O O O O O O 99 38. Changes of shear force during preparation Of kidney beans 0 O O O O O O C O O O O O O O O O 100 39. Changes of ash content during preparation Of navy beans 0 C O O O O O O O O O O O O O O I O 102 40. Changes of ash content during preparation Of kidney beans 0 O O O O O O O O O O O O O O O O 103 41. Cooking temperature effect on hydration ratio of navy beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak . . . . . . . . . . . . . . . . 114 42. Cooking temperature effect on hydration ratio of kidney beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak . . . . . . .'. . . . . . . . . 115 43. Cooking temperature effect on shear force of navy beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak . . . . . . . . . . . . . . . . 116 44. Cooking temperature effect on shear force of kidney beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak . . . . . . . . . . . . . . . . 117 Figure Page 45. Cooking temperature effect on total solids of navy bean cook water with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak . . . . . . . . . . . . . . . . 120 46. Cooking temperature effect on total solids of kidney bean cook water with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak . . . . . . . . . . . . . . . . 121 47. Z-value evaluation of navy beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak . . . . . . . 122 48. Z-value evaluation of kidney beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak . . . . . . . 123 xi INTRODUCT ION The food legumes, of which dry edible beans (Phaseolus vulgaris L.) are an example, are important sources of essential protein, calorie, vitamins, and minerals. They are foods of choice worldwide and are a major source of protein in diets of people in developing countries and vegetarians who eat primarily food from cereal and root crops. Dry edible beans may be prepared in several ways. In households, they are cooked, fried, or baked to be used in soups, eaten as a vegetable, or combined with other protein foods to make a main dish. Commercially, they are procesed in cans to produce a number of bean-based foods. However, several problems are encountered in bean utilization which include long soaking and cooking time necessary to adequately soften the beans, loss of valuable nutrients during bean preparation, flatulence, and antinutritional factors. Many studies have been devoted to investigating factors affecting cooking quality of beans in the attempt to reduce the preparation time. Researchers have also tried to eliminate flatus-causing components and antinutritional factors from beans. This study was undertaken to evaluate the physical and l chemical changes occurring in dry edible beans during cooking preparation. The experiment was divided into two studies. In Study 1, two soaking methods (hot soak, two minutes boiled and one hour held; cold soak, 2 to 16 hours at room temperature) were examined. Soaked beans were then cooked separately in a blancher at 190 OF (87.8 °C). In the second part, only cold-soaking was applied and all bean samples were cooked together in a steam kettle at 190 °F (87.8 0C). Both physical and chemical changes in beans were evaluated in Study I. The effect of cooking temperature was examined in Study II, in which beans were cold—soaked and cooked at four different temperatures, 181.3 0F, 190.7 0?, 200.0 OE, and 207.5 °F (82.9 °C, 88.1 °C, 93.3 °C, and 97.5 0C). Only the physical changes in beans were investigated in this study. REVIEW OF LITERATURE Food legumes belong to the genus Phaseolus and include such beans as common, kidney, field, garden, or haricot The majority of legumes grown in the United States belong to Phaseolus vulgaris species which include Great Northern, pinto, black, small white or navy, red, and yellow eye beans (Deschamps, 1958). Dry Bean Composition Seed Composition §gg§ 9335. The capacity of beans to imbibe water is determined by the structure and composition of seed coat, as well as the environmental conditions during harvesting and storage. The seed coat, which constitutes 7.7% of dry matter of mature beans (Powrie et al., 1960), is found to be the primary barrier for water to pass into the bean. Ott and Ball (1943) studied the relation between cell wall pectic substances, which are the polyuronide and “true pentosans" and constitute about 40% of the dry weight, and water retention of the seed coats. Reeve (1946) studied the relationship between histological characteristics and texture in the seed coats of peas and stated that during 3 maturation there is the formation of a highly specialized, epidermal structure composed of macrosclerid cells as well as development of a pentosan-cellulosic compound. which causes remarkable thickening and hardness of the cell wall. Protein content of the seed coat is reported to be 5.07% of the seed coat dry weight (Ott and Ball, 1943), which is in agreement with the protein content of 4.8% as found by Powrie et a1. (1960). Snyder (1936) also reported the protein content in seed coats of "soft" and "hard" Michigan pea beans to be 5.6 and 6.8% respectively. Snyder (1936) mentioned that the amount of protein in the seed coats of beans may be related to hardshell character, but Ott and Ball (1943) did not find any correlation between water retention and protein content. Cotyledon. Cotyledons are the most important compo— nents of the bean seed with respect to weight and volume as well as for contributing to texture and nutritive value of processed beans. According to Powrie et a1. (1960), the cotyledons constitute 90.5% of dry bean matter. Epidermal cells are the outermost layer of the cotyledon. The cell contents are microscopically granular and this granular structure is presumed to be of proteinaceous nature. Starch granules are not found in this layer. The next inner layer of the cotyledon is the hypodermis. The cells of this layer are elliptical in shape and are larger than epidermal cells. The cell contents are granular and composed of protein but 5 no starch. The remaining tissues of cotyledons are paren- chyma cells and vascular bundles. Starch granules are found to be imbedded in a protein matrix of each parenchyma cell. The secondary walls of parenchyma cells are observed to be very thick as compared to the primary wall and contain numerous small cavities and pits which facilitate the migra- tion of water during the soaking period. However, Snyder (1936) noted that the major areas through which water passes into beans are the micropyle and germinal areas. Protein Content Dry beans are good sources of protein. Many research- ers (Watt and Merrill, 1963; Meiners el al., 1976a; Tobin and Carpenter, 1978; and Koehler and Burke, 1981) have reported the protein content of common beans (white beans, navy beans, pink beans, and red kidney beans) to be in the range of 21% to 25.5% on dry weight basis. However, Koehler and Burke (1981) found the protein content of large dark red kidney beans to be as high as 32.8%. Several studies have been done on the loss of protein from beans during cooking. Meiners et al. (1976a) reported 50% to 60% protein loss after beans were cooked in excess water until tender, while Koehler and Burke (1981) reported only a 3% to 10% reduc- tion. Haytowitz and Matthews (1983) showed that during cooking, protein is not destroyed but small amounts may leach into the cooking water, and that protein retention is 93% to 100%. Ash and Minerals According to the literature, the total ash content of raw beans is in the range of 2.9% to 4.9% on dry weight basis (Watt and Merrill, 1963; Fordham et al., 1975; Meiners et al., 1976a; Tobinand Carpenter, 1978; and Koehler and Burke, 1981). Considerable decrease of the ash content after cooking has been observed by many researchers due to the leaching of minerals into cooking water. Watt and Merrill (1963) reported a 10% decrease of the ash content, whereas Meiners et al. (1976a) and Koehler and Burke (1981) noted the losses of 55% to 70% and 20% respectively. The reported percentages of decreases vary in a wide range, possibly due to different methods of cooking. The ranges of specific mineral contents in mature, raw beans of Phaseolus vulgaris, which are reported by several researchers, are summarized in Table 1. Great variations are found in cer- tain minerals because of the differences in the growing location, soil composition and varieties of beans. Atomic absorption spectrometry is used by many researchers to de- termine most minerals, except for Walker and Hymowitz (1972) who used emission spectroscopy in their analyses. Augustin et a1. (1981) employed flame emission spectrometry to mea— sure sodium and potassium. Phosphorus is determined colori— metrically by Meiners et al. (1976b) and Augustin et a1. (1981). As seen in Table l, beans contain relatively high .pmuxamcm mum3 mammn muwns HHmEm 0cm .pmu HHmEm .pmuxamcm mum: mcmwn cmowxmz no» can .oowamu .oucwm .pwu .muwnz . .nmuhamcm mum: mcmwn xmcpmx emu new .mumnz .xoman .>>mz .pmuxamcm mum: mcmmn chpwx own new .oucwm .cuonuuoz amouo .>>mz .nmuxamcm mum: mcmmn xmcpwx own new .oucflm .xcwm .pmu Hamem .pmuaamcm mum: momma cucwa 0cm .>mcpwx own .a>mc .CDwnuuoz umwuo .Oucwm .xch .xmcomx no» .>>mc .Cumnuuoz umwuo .xuumncmuo .xomam .coHHHME you wanna cw pmuuommu mum mmsHm> HH< . o o o o Hvamor’“ omeHIcwmm I Ohmvlomov o¢HI00H I I thvm I ovvaIOHHH hamwmav Hawuuwz 0cm uum3 oovaHIoomaa . mNIhH ooomloomN I omlw oomanoma mmaumw NHIQ ooomlooHH wAmhmHV uuwzofi>z new uoxHMS hoomaImowm mNIHN ooamlowhm mMIhH mHIOH mthIOMNH mhlmm mlb NHmHImmm mAnmhmHV .Hm um mumcMmz ONHNHIowmmH ovam I I I I mmlmh I ONONIomMH vAHmmH. mxuom 0cm umanmox omNmHIommoa I omomlomwm I NMNIMha NNNNIONwH mmIMH I womHIomoa nfimhmav .Hm um Encouom oomhaloomma mwlaa cahmIoomm OHNIov ONIOH oommIoowH omlmm «HIm OOHNIOON NAHmmHV .Hm um cfiumsmsé 2 cu m nz a: m: mm 90 no mocmumumm .mmmmmao mmummas> msfiowmmnm ousume .3mu uo mHaumcmE cmuowawm uo mucwucou .a manna A 8 amounts of calcium, iron, magnesium, phosphorus, and potas— sium. Mineral contents reported by all researchers are found to be in good agreement except for manganese and sodium. These variations may be due to the varietal differ- ences, cooking methods, or methods of analysis. Retention of various minerals during cooking of beans has been studied (Table 2). Meiners et al. (1976b) cooked until tender ten varieties of legumes in’an excess amount of water and determined the contents of nine minerals in both raw and cooked samples. It was found that minerals in cooked legumes were about one-third to one-half of the values in raw legumes, and cooking water contained measur- able amounts of all minerals, with relatively high amounts of magnesium, phosphorus, and potassium. Augustin et al. (1981) cooked beans of nine different commercial Phaseolus vulgaris classes in adjusted amounts of water such that no more than 50 ml of cooking water remained after cooking and with the experimental procedures designed to minimize mineral contamination from outside sources. Mineral values in cooked samples were higher than in the corresponding uncooked samples. Retention of minerals during cooking was in the range of 80% to 90% with the exception of 38.5% sodium retention and total calcium retention. Koehler and Burke (1981) looked at the calcium, iron, potassium, and zinc contents in raw and freeze-dried (following cooking) beans of seven cultivars and found close agreement in miner— al retention with Augustin et a1. (1981). .cowaame non muumm cw pmuuomou can mosflm> came mum mmsHm> Hac .H mmmm oncoa ooama pmxoou named comma oovma 3mm Esmmmmuom Ha mm on cmxoou m~ mm mm 30m Uch omma I oomv nmxoou omvv I oomv 3mm msuocmmocm wm I «m omxoou mm I moa 3mm Esmpom m I ma cmxooo «A I vH 3mm mmmcmmcmz mom I coma omxoou hmma I ooom 3mm Eofimmcmmz n.om >.~h v.wm pmxoou m.wm o.vm «.mm 3mm couH m.~ I H.n nwxoou m.h I m.m 3mm ummmoo ham mvna coma pmxoou omma mmha coma 3mm Esfloamu Anmnmav .Hg 90 numcfiwz .Hmmav oxusm can umHnwox AdmmH. .Hn um cmumsmsa mucoumumm “.mmmmmau muunuas> msflommmcm cuxooo can 3m» uo mamuocfia couooamm mo mucmucoo .N manna 10 Variabilities between and within classes of beans as well as the effect of growing locations have been investi- gated (Table l). According to Augustin et al. (1981), calcium variabilities are high both between and within classes, although growing area has little effect. The data are in close agreement with those of Watt and Merrill (1963), Walker and Hymowitz (1972), and Meiners et al. (1976b). The variability of copper and iron are about the same between and within classes; the effect of growing area on iron content is noticeable only in navy beans. Copper levels are similar to those reported by Walker and Hymowitz (1972), Meiners et al. (1976b), and Rockland et a1. (1979), whereas iron levels are lower than those reported by Walker and Hymowitz (1972), Meiners et al. (1976b), and Koehler and Burke (1981), but are in fair agreement with those of Fordham et a1. (1975). Little variability and small loca- tion effect are found for magnesium and the data agree with the values from Watt and Merrill (1963), Fordham et a1. (1975), and Meiners et al.(1976b). The variability of man— ganese is found to be high by both Fordham et al. (1975) and Augustin et al. (1981). The range of manganese appears to be wide which is presumed to result from different growing locations. Similarly, sodium variabilities between and within classes are very high. Augustin et a1. (1981) sug- gested that this variability may be associated with the analysis method as a result of very low sodium concentration on beans. The data agree well with those of Watt and 11 Merrill (1963) but are dramatically lower than those of Meiners et al. (1976b). Both Meiners et al. (1976b) and Augustin et al. (1981) noted low variability of phosphorus and remarkable effect of growing area. All data in litera- ture are in good agreement. Whereas Meiners et al. (1976b) observed the least variability for the zinc content, Augustin et al. (1981) found the overall variability of this element to be high. Potassium shows low variability between and within classes grown in the same location, but those grown in different areas show high variability within classes. All data from literature are reasonably in good agreement except the high potassium content observed by Koehler and Burke (1981). It may be presumed that variation in all minerals is due to differences in soil composition, growing location, and the method of analysis. Relationship between mineral contents and -proximate composition in twenty-eight varieties of Phaseolus vulgaris is studied by Walker and Hymowitz (1972). Significant negative correlations are found between fat content and contents of calcium, iron, and zinc. Significant correla- tion coefficients are also noted between raffinose content and contents of phosphorus and potassium. It is concluded that the relationships found are not directly proportional since the correlation coefficients are all less than 0.60, although they are statistically significant. 12 Carbohydrates The total carbohydrates of dry legumes range from 24.0% in winged beans to 68.0% in cowpeas (Reddy et al., 1984). Starch constitutes the most abundant legume carbohydrate ranging between 24.0% to 56.5%. Other carbohydrates include monosaccharides, oligosaccharides, and polysaccharides. Total sugars (monosaccharides and oligosaccharides) repre- sent only a small percentage of the total carbohydrates. Among the sugars, oligosaccharides of the raffinose family (raffinose, stachyose, verbascose, and ajugose) predominate in most legumes and account for 31.1% to 76.0% of the total sugars (Akpapunam and Markakis, 1979; Ron, 1979; Rockland et al., 1979; Ekpenjong and Borchers, 1980; Reddy and Salunkhe, 1980; Fleming, 1981; and Sathe and Salunkhe, 1981). The predominance of a particular oligosaccharide is likely to depend on the legume type. Stachyose represents the major oligosaccharide in most varieties of Phaseolus vulgaris (smooth and wrinkled peas, Great Northern beans, California Small White beans, red kidney beans, navy beans, pinto beans, pink beans, black eye beans, and cowpeas). Raffinose is present in moderate to low amounts in most legumes. Legumes also contain appreciable amounts of crude fiber (1.2% to 13.5%, Reddy et al., 1984), with cellulose being the major component, followed by hemicellulose, lignin, pectic and cutin substances. Oligosaccharides of the raffinose family (raffinose, l3 stachyose, and verbascose) are reported to be, at least in part, responsible for the flatulence problem in humans and animals. Several studies have been done on flatus and flatus formation (Steggerda, 1968; Rockland et al., 1969; Sanchez et al., 1969; Levine, 1979; and Fleming, 1981). The sugars of the raffinose family cannot be absorbed through the intestinal wall and cannot be digested by humans because the intestinal tract does not contain the enzyme (<1-l,6- galactosidase) necessary to split these oligosaccharides into simple sugars. These indigestible oligosaccharides pass through the small bowel and enter the colon where bacteria can readily utilize them as fermentation substrates and produce large amounts of carbon dioxide and hydrogen and a small quantity of methane (Levine, 1979; and Olson et al., 1981). The degree of flatulence produced is related to the level of oligosaccharides in beans. However, some studies (Fleming, 1981; Olson et al., 1975 and 1982; Wagner et al., 1976 and 1977) revealed that flatus-producing capacity of beans is not totally eliminated by removal of oligosaccha— rides, thus suggesting that there are other substances that contribute to flatulence. Olson et a1. (1975) found that protein is not a significant cause of flatus. Reddy et a1. (1984), in reviewing studies pertaining to this problem, mentioned that fiber, which is one major undigestible compo- nent in beans, may be involved in the fermentation by micro- organisms and subsequent flatulence production, and that further research is needed to understand the role of fiber 14 in this problem. Various approaches have been studied and suggested in order to reduce the flatus-production capacity of beans. One of the possible methods is to genetically develop spe- cial varieties of beans with low levels of sugars of the raffinose family. Another method is to add antibiotics or bacteriostat to bean products in order to inhibit the activity of intestinal bacteria and subsequently eliminate flatulence-causing compounds. However, this method is not considered acceptable and may cause changes in organoleptic properties of the products (Steggerda, 1968). Substantial amounts of flatus-producing components in beans can also be eliminated by various common processes (soaking, cooking and discarding the cook water, germination, fermentation, or a combination of the aforementioned processes). Since the sugars of raffinose family are water-soluble, discarding the soak and cook waters will remove most of these sugars from beans. Ku et a1. (1976) reported 33% to 59% decrease of sugars of raffinose family from soybeans when cooked in a one to ten bean to water ratio. Silva and Luh (1979) noted 90.6% and 88.1% reduction of these oligosaccharides from soaking of black eye and pink beans, respectively. Whereas Iyer et a1. (1980) observed 32.8% to 51.0% reduction in Great Northern, kidney, and pinto beans after soak water is discarded. These beans are cooked at 100 0C for 90 minutes and the decrease of 70.3% to 80.2% is found when both soak and cook waters are discarded. Reddy and Salunkhe (1980) 15 pointed out that the reduction of oligosaccharides from soaked and cooked beans is primarily due to leaching effect. A combination of various treatments can also be employed to remove oligosaccharides from beans. Recently Olson et a1. (1981 and 1982) developed a boil-soak method in which beans are boiled for three to four minutes (in 1:5 to 1:10 bean to water ratios) and then allowed to stand at room temperature. These workers observed over 90% removal of sugars of raffi- nose family from various common beans (light red kidney, California Small White, pinto, and black eye). In addition, over 70% of oligosaccharides are depleted during germination (Reddy et al., 1984). Bean Preparation Soaking During soaking, beans imbibe water which leads to softening of seed coats and thus decreases the cook time required to obtain desirable texture. The capacity of beans to absorb water depends greatly on their own physical— chemical composition and seed coat which is said to be the primary barrier to the migration of water into the bean. Snyder (1936) observed and found no beneficial effect of scarification or removal of seed coat on tenderness of beans. However, Kon et a1. (1973) noted a reduction of cook time when seed coat was removed. The work by Ron et a1. (1973) is supported by Varriano-Marston and de Omana (1979) 16 who investigated the effects of accelerated storage on water absorption and cook time. However, Muneta (1964) found that the presence of a seed coat affects subjective evaluation of bean products. Various additives in soak water have been employed by a number of researchers. Such additives include ethylene diamine tetracetic acid (EDTA), sodium bicarbonate, sodium hexametaphosphate, sodium chloride, sodium carbonate, sodium bisulfite, oxalic acid, ammonium oxalate, citric acid, malic acid, acetic acid, hydrochloric acid, sulphates and chlorides of calcium and magnesium. Hoff and Nelson (1965) reported that EDTA has no sig- nificant effect on water imbibition of dry pea beans, nor does it affect the increase in firmness of navy, pinto and kidney beans as shown by Junek et a1. (1980). However, EDTA is found to help preventing discoloration of canned dry lima beans (Luh et al., 1975) by its chelating action to immobi- lize metal ions. EDTA also reduces the chemical oxygen demand (COD) in wastewater by its chelating action with divalent metals in soak water (Neely and Sistrunk, 1979). Addition of sodium bicarbonate tends to soften the seed coats of beans and can be used effectively in amounts which are not deleterious to appearance or flavor (Snyder, 1936). The same conclusion was made by Dawson et al.(1952) who found a 42% increase in water absorption of beans by adding NaHCO3. Sodium salt solutions were used by Rockland and Metzler (1967) in quick-cooking of dry beans in which the l7 beans were soaked in a solution containing NaCl, Na5P3010: NaHCO3 and Na2C03 and the resulting product was cooked in less than fifteen minutes. Work done by Varriano-Marston and de Omana (1979) also showed that black beans soaked in N3593°10 and Na2C03 solutions absorbed the most water. They suggested that the beneficial effect of adding sodium salts was a solubilization of pectic substances during soaking and cooking due to ion-exchange in which the sodium ions replace divalent ions. Snyder (1936) reported that addition of hydrochloric acid and acetic acid of various concentrations tends to depress water absorption and harden the seed coats due to the presence of hydrogen ions (increased acidity), thereby reducing the rate of water imbibition. This researcher also mentioned that addition of ammonium salts of oxalic, citric and tartaric acid softens the seed coats of beans. Ammonium salts of oxalic acid are the most efficient. Nordstrom and Sistrunk (1977) observed an increase of shear press value when pinto, red kidney, and Dwarf Horticulture #4 were processed in the acidic medium, tomato sauce (pH 5.0 to 5.2). This work was supported later by Junek et a1. (1980) who found that addition of citric and malic acids increases the firmness of navy beans as measured by shear force. The decrease in drained weight was observed as well. Luh et al. (1975) also noted a decrease in drained weight when higher concentration of citric acid was added. Varriano-Marston and de Omana (1979) observed an increase in acidity of soak 18 water during the soaking process which resulted primarily from the loss of hydrogen ions from cellular components. It was proposed that starch is one of the physical-chemical barriers in water absorption and that an acidic environment leads to a decrease in starch swelling potential, thus decreasing the ability of beans to imbibe water. Lai and Varriano-Marston (1979) observed a direct positive increase in solubility with increased swelling power and noted that solubilization and starch swelling are restricted during cooking. Phosphate solutions have also been employed in soaking by many researchers. Mattson (1946) observed the dephos- phorylation of phytic acid due to inactivation of the enzyme phytase in the presence of heat. Consequently the phytic acid precipitates out calcium and magnesium ions and the tough Inetal-pectin cross-linked products are not formed. The use of polyphosphates by Hoff and Nelson (1965) resulted in a great increase in water imbibition, which may be due to the chelating mechanism of the polyphosphates with divalent metal ions, thus preventing the formation of tough metal cross-linked pectates. Later work by Lee (1979) showed an increase in water absorption and softness of beans when sodium hexametaphosphate (NaHMP) was added, but there was leaching of soluble solids as well. This worker also noted a decrease in drained weight when the combination of calcium ions and NaHMP was used. Snyder (1936) looked at the effect of adding minerals to 19 the soak water and reported that solutions of sulphates and chlorides of calcium and magnesium of 100 ppm depress water absorption and harden the seed coats. The hardness increases with corresponding increase of solution concentration. How- ever, this researcher did not find deleterious effects on beans when chlorides of sodium and potassium were used. This was supported later by Luh et a1. (1975) and Davis and Cockrell (1976) who noticed that the addition of calcium chloride to the brine resulted in firmer products, with the formation of firm calcium pectates. Both also found that the shear press values of canned lima beans increased with the (increased concentrations of calcium chloride. Quenzer et al. (1978) also reported a positive correlation between shear press values and calcium content, and a negative correlation between water absorption capacity of beans and calcium content. Cooking and Processing Various factors that affect the cooking quality of dry beans include the composition of seed coats, storage condi— tions, soaking treatments, blanching treatments, and cooking conditions. A number of studies have been done in the attempt to decrease the cook time necessary to obtain a desirable and palatable product. Snyder (1936), in studying the cooking quality of Great Northern and pea beans from various states in the United States, found that differences in place of origin do not contribute marked differences in 20 cooking quality of the beans studied, and that the size of beans had a negligible effect on cooking quality. This researcher also noted pronounced effect of storage condi- tions and concluded that beans should be best stored in tightly closed containers at a temperature around 45 °F. Studies by Burr et a1. (1968) and Antunes and Sgarbieri (1979) revealed that as the storage temperature increased, the rate of hydration decreased and the cook time increased. Their observations also showed that cooking time decreases directly with the decrease in storage temperature and humidity. Studies on the effect of storage time have been conducted by Morris (1963 and 1964), Burr and Kon (1966), Burr et a1. (1968), and Bedford (1972). Burr and Kon (1966) found that pinto beans, when subjected to prolonged storage for one (year, needed 62 minutes at 121 °C to cook until tender while freshly harvested beans required only 23 minutes. Relative humidity and bean moisture content also play important roles in the cooking ability of beans. During storage, high relative humidity and high bean moisture lead to mold growth, development of off-flavors, lipid oxidation, color darkening, and development of hardshell beans (Morris, 1963; Muneta, 1964; Burr et al., 1968; Bedford, 1972; and McCurdy et al., 1980). Gloyer (1928) reported an increase in percentage of hardshell beans with lower storage humidi— ty, while Bourne (1967) noted that the hardshell beans tended to be smaller in size than non-hardshell beans. Kon 21 (1968) noted a very substantial increase in cook time for high moisture beans stored for four years. Molina et a1. (1976) mentioned that the hard-to-cook phenomenon could be reduced if heat treatment was applied to beans prior to storage. He also observed the hardness of black beans stored at 25 °C and 70% relative humidity for nine months. Morris (1963) and Burr and Ron (1966) reported that storing beans at low moisture content was essential to preserve their cooking quality. An increase in cooking time was observed with high moisture stored beans (Burr et al., 1968). Pinto beans stored at 25 °C and 16% moisture required 60 minutes to cook as compared to 20 minutes for beans stored at the same temperature at 8.2% moisture. Rockland (1963) found that beans of 9.9% initial moisture content require one—fifth the cooking time of beans stored for five months at 32.2 0C with 13.3% initial moisture. However, Jackson and Varriano-Marston (1981) noted an inverse proportion between moisture content and cooking time in black beans. Various cooking treatments have been investigated by a number of researchers. The Michigan Bean Commission devel— oped a standard method of bean preparation, in which beans are soaked either by cold-soaking or hot-soaking. In cold- soaking, beans are soaked in six cups of cold water and two teaspoons of salt for every pound of beans. Hot-soaking is done by bringing a pound of beans and six to eight cups of water to boil, cooking for two minutes, removing the beans 22 from the heat, and allowing to stand for one hour. After that the beans are cooked by simmering over ‘medium-heat until tender for an approximate cooking time suggested for each particular bean type. For instance, for one cup of soaked beans, 1.5 hours are required for navy and pinto beans and two hours for black and kidney. Snyder (1936) recommended the optimum soaking temperature of 120 °F for Great Northern and pea beans in which the beans imbibe their own weight of water in five and six hours. She also added that a longer cooking time is required if soaking is done at a lower temperature. Quast and da Silva (1977) observed that by raising the cooking temperature by 10 °C for black beans, the cooking time is decreased by 3.36 fold. Kon (1979), studying the effect of soaking temperature, found that soaking beans at elevated temperatures increased the rate of water imbibition and decreased the time required for maximum water absorption. Junek et al. (1980) noted that when soaking temperature was raised from 15 0C to 35 0C, the shear peak height decreased. A quick-cooking method was developed by Dawson et al. (1952) and Quast and da Silva (1977). Dawson et a1. (1952) found that adding beans to boiling water for two minutes followed by soaking in hot water for one hour resulted in products of higher quality than those cooked by the standard method. The latter researchers found that cooking beans for nine minutes at 127 °C resulted in the same quality of products as those cooked at 98 °C for 260 minutes. However, 23 both Dawson et al. (1952) and Quast and da Silva (1977) pointed out that a sufficient process time should be employed to ensure commercial sterility of the product. Rockland and Metzler (1967) and Rockland et a1. (1979) also studied the quick-cooking method of beans. The method developed by Rockland and Metzler (1967) included loosening the seed coats by vacuum filtration in a solution containing NaCl, Na5P3010, NaHCO3 and Na2c03; soaking the beans in the same salt solutions; rinsing; drying; and cooking or freezing depending on their ultimate utilization. The resulting product cooked in less than fifteen minutes. Rockland et a1. (1979) observed quick-cooking of winged beans by blanching in boiling water for two minutes; soaking 24 hours in soak water containing various salts; and cooking for 15 to 20 minutes in boiling water. Effect of blanching was examined by Davis (1976), who concluded that beans absorbed more water and lost fewer solids when blanched below the boiling point of water than those blanched at the boiling point. He also found great effect of processing time on the firmness of pinto and red kidney beans and suggested that one should increase tempera- ture rather than time when processing for the desired texture in navy beans. Brown and Kon (1970) observed a decrease of cooking time from 80 minutes to 30 minutes when seed coats were removed, thus supporting the theory that 24 seed coat is the primary barrier to water absorption. Daoud et a1. (1977) noted 5 to 8% losses of vitamin B; in steam- blanched beans while water-blanched beans showed 10% to 15% losses. Nordstrom and Sistrunk (1979) found that steam blanching resulted in firmer beans, but less leaching of starch and pectin, than hot water blanching. However, Davis et a1. (1980) observed that steam-blanched beans were firmer than those being hot water-blanched. MATERI ALS AND METHODS The present work consists of two separate studies. Study I evaluates physical and chemical changes of beans during cooking preparation. Study II examines the effect of cooking temperature on physical properties of beans. Navy beans (Seafarer) and red kidney beans (Montcalm) were used in both studies. Material Preparations Initial moisture of dry beans to be used in the experiment was measured and the fresh weight corresponding to 100 grams of bean solids was calculated. Bean samples were weighed according to the fresh weight obtained. They were then soaked and cooked according to the procedures described below. Moisture The initial moisture content (% by weight) of dry bean samples was measured by using the Motomco Moisture Meter (Model 919, Motomco Inc., Clark, NJ). All measurements were performed according to the manufacturer's instructions. The fresh weight of dry beans to yield the required solids was 25 26 calculated as follows: % Solids at given moisture = 100 - %Initial moisture content , , Solids required (9) Requ1red fresh weight (g) = % Solids at given moisture X 100 Each bean sample was weighed to yield 100 grams of dry bean solids, which was the sample size used in both studies. Soaking and Cooking The soak water and cook water used in both studies were distilled water containing 100 ppm of calcium (see Appendix for calculation). The following three different methods of cooking were employed in the two studies: 1. Blancher cooking at 190 1 2 OF (87.8 i 1.1 °C) 2. Kettle cooking at 190 i 2 05‘ (87.8 i 1.1 °C) 3. Temperature variation cooking The first and second methods were incorporated into Study I, in which the physical and chemical changes in beans were investigated. The third cooking method was Study II, where the effect of cooking temperature was evaluated. Sample preparations for each cooking method are described in detail as follows. Blancher Cooking. Two methods of soaking were investigated. 1. Cold soaking. Eight samples of beans were soaked in 27 plastic containers at room temperature for 2,. 4, 6, 8, 10, 12, 14, and 16 hours respectively (1:4, beanzwater). 2. Hot soaking. A sample of beans was added into boiling water (with the same bean to water ratio as above) and allowed to stand for two minutes, after which it was removed from heat and allowed to cool to room temperature for one hour. When the desired soaking time was reached, each sample was drained on a No.8 standard sieve for two minutes. The weight gained after each soaking was measured and the hydration ratio was determined. Then the soak waters were stored frozen in plastic zip-lock bags for subsequent total solids determination. The soaked beans were weighed, dried in an air-oven dryer (Precision Scientific Co., Chicago, IL) at 80 0C for 24 hours, and reweighed to obtain the oven— dried weight. Dried beans were ground in a Cyclone Sample Mill (U.D.Y. Corporation, Fort Collins, CO) and bean flour samples were stored at room temperature in plastic zip-lock bags for chemical analyses. The 16 hour cold-soaked and hot-soaked beans were cooked in the blancher at 190 OF (87.8 0C) for 30, 60, and 90 minutes respectively. Each soaked sample was placed into a 1000 ml flask and boiling cook water was added into each flask to yield bean to water ratio of 1:4. The flasks were covered with aluminum foil and immersed into the blancher containing water, which had been previously heated to reach the cooking temperature of 190 °F (87.8 °C). When the 28 desired cooking time was reached, the flasks were removed from the blancher and the beans were drained on No.8 stan- dard sieves for two minutes. The weight gained after cook- ing was measured and the hydration ratio was determined. Cook waters were stored frozen for further determination of total solids. Texture measurement was performed on all cooked samples. The shear residues were weighed and dried in an air-oven dryer (Precision Scientific Co., Chicago, IL) at 80 °C for 24 hours. The oven-dried weight was measured and the bean percent total solids was calculated. The dried residues were ground and stored as previously described. Kettle Cooking. Beans were soaked at room temperature in plastic containers (1:4, bean:water). The soaking times were 0 (raw beans), 8, 12, and 16 hours. The time schedule was so arranged that the soaking processes terminated at the same time. Immediately after soaking, the beans were put into a steam kettle containing preboiled water. The bean to water ratio used for cooking was one to eight in order to prevent burning due to insufficient cook water. The beans were boiled for five minutes and the temperature was then brought down to 190 °F (87.8 °C). The cooking times applied were 30, 60, and 90 minutes respectively. When the desired cooking time was reached, bean samples for each soaking time were drawn from the kettle and the texture measurement was performed. The shear residues were dried, ground and stored as previously described. 29 Temperature Variation Cooking. Bean samples were soaked in the same manner as described in kettle cooking, except that the soak times were 0 (raw beans), 6, and 12 hours respectively. Each sample was placed in separate 1000 ml flasks and boiling water was added into each flask to obtain 1:4 bean to water ratio. The flasks were covered with aluminum foil and immersed into the blancher containing water, which was heated to get the nearest desired cooking temperature of 180 OF, 190 OF, 200 OF, and 210 OF (82.2 °C, 87.8 °C, 93.3 °C, and 98.9 °C) respectively. Cooking at each temperature was performed separately. The cooking times were 30, 60, and 90 minutes. When the desired cooking time was reached, bean samples of each soaking were drawn from the blancher and determination of hydration ratio and texture were conducted. The shear residues and cook waters were handled in the same manner as in Study I. Raw navy and kidney beans were also prepared to serve as control samples in chemical analysis. They were ground in a Cyclone Sample Mill (U.D.Y. Corporation, Fort Collins, CO) and stored in plastic zip-lock bags. Methods of Analysis Texture After cooking, the cooked beans were evaluated for tex— ture using an Allo-Kramer Recording Shear Press (Model TR-l, 30 Food Technology Corp., Reston, VA). The 3000 pound trans- ducer and No. C-15 standard shear compression cell were used. The rate of shear compression blade travel was 0.52 cm/sec. A sample of 100 grams cooked beans was placed in the cell, evenly distributed, and sheared. The entire cell was cleaned and rinsed between each measurement. Duplicate readings were taken for each sample. The typical Kramer shear peak is shown in Figure l. A firm bean requires greater force to shear, as indicated by a higher peak height, than a soft bean. Certain bean varieties produce two peaks: a predominant shear peak (Type A) and a predominant compression peak (Type B) (Hosfield and Uebersax, 1980). For texture evaluation of samples in the current study, the compression peak height was recorded and the shear force (lbs/100 grams bean) was calculated as follows: Shear force = Peak height x transducer force (3000 lbs) X instrument range (1/1 or 1/3) Hydration Ratio After soaking and cooking, beans were drained on No.8 standard sieves for two minutes and weighed. Hydration ratio was calculated as follows: Weight after soaking/cooking (9) Bean fresh weight (g) Hydration Ratio = PEAK HEIGHT 31 SHEAR PEAK COMPRESSION PEAK INITIAL CONTACT TIME Figure 1. Typical Kramer shear peak for bean texture evaluation. 32 Total Solids in Soaked and Cooked Beans Soaked beans and shear residues were weighed and dried at 80 °C in an air-oven dryer (Precision Scientific Co., Chicago, IL) for 24 hours. The oven-dried weight was mea— sured and the percent total solids in beans was determined as follows: . 0 n-d ied WEI ht % Total SOlldS = :fiitle weigh: (9:9) X 100 Total Solids in Soak and Cook Waters The frozen soak and cook waters were thawed at room temperature. A homogeneous sample of 100 grams was placed into a dry, preweighed aluminum pan and dried at 100 °C in a Proctor-Schwartz dryer (Proctor and Schwartz; Inc., Phila- delphia, PA) to a constant weight. The sample pans were then allowed to cool and the final weights were measured. Total solids was determined as follows: , Pan final weight (9) Ash Determination Five gram samples were weighed into previously dried, cooled and weighed 50 ml porcelain crucibles. Samples were dried at 80 0C for 24 hours in an air-oven dryer (Precision Scientific Co., Chicago, IL). After being cooled in a des- iccator, samples were burned on a Labconco micro-Kjeldahl 33 burner unit (Labconco Corp., Kansas City, MO) until smoke disappeared; they were then incinerated at 525 °C for 24 hours in a Barber-Coleman muffle furnace (Model No.293 C, Thermolyne Corp., Dubuque, IA). The ash residue was allowed to cool to room temperature in a desiccator and weighed. The ash content was calculated as follows: . Residue weight (g) % Ash (dry ba51s) = Sample weight (g) X 100 Protein Determination The protein content was determined by Micro—Kjeldahl method according to AACC method 46-13 (1983). Percentage of nitrogen and protein content were calculated as follows: (m1 HCl-ml BlankaX Normality of HCl X Eq.Wt.of N %N = Sample weight (mg) X 100 Protein content (% dry basis) = 6.25 X %N Mineral Analysis An inductively coupled plasma (ICP) emission spec- trometer (Jarrell-Ash Model 955 Plasma Atomcomp; Fisher Scientific Co., Pittsburgh, PA) was used to determine Ca, Cu, Fe, Mg, Mn, Na, P, Zn, and K contents for each sample. Equipment Handling. All crucibles, volumetric flasks, funnels, and culture tubes used in preparing samples were specially cleaned. After being washed with detergent and 34 rinsed with distilled demineralized water, they were soaked overnight in a 3N Baker Instra-analyzed nitric acid solu- tion, rinsed three times with distilled demineralized water, allowed to air dry and were stored separately from other laboratory glassware. Several samples of the distilled demineralized water were analyzed for mineral content and found to contain below detectable amounts of the minerals to be determined in this study. The muffle furnace was washed and thoroughly rinsed with the distilled demineralized water before each use. Sample Preparation. One gram sample of previously dried flour was weighed into 50 m1 porcelain crucibles and heated on a Labconco micro-Kjeldahl burner unit (Labconco Corp., Kansas City, M0) on a low setting for 20 to 30 min- utes until all smoke dissipated and the samples appeared charred. Samples were then placed in a Barber—Coleman muffle furnace (Model No. 293C, Thermolyne Corp., Dubuque, IA) at room temperature. Samples were ashed at 500 0C for approximately 16 hours. When cool, the residue remaining in each crucible was dissolved in two ml concentrated Baker Instra-analyzed nitric acid for approximately one hour. The dissloved residues were transferred to 10 ml volumetric flasks, which contained one ml of 100 ppm Yttrium oxide solution (internal standard), and brought to volume with demineralized distilled water. The mineral solutions were transferred to labeled polypropylene culture tubes. The 35 tubes were capped and refrigerated overnight. If the solu- tions contained visible sediment the next day, the solutions were Adecanted into clean culture tubes so that only clear solutions were used for mineral analysis. For approximately every 20 flour samples, a procedural blank, which contained no sample material, and a sample of standard reference material (SRM) #1572, which was citrus leaves (National Bureau of Standards, Washington, D.C.), were prepared. The procedural blank and the standard reference material re- ceived the same treatment as did flour samples. All flour samples, SRM, and procedural blank solutions were stored at -20 °F (-28.9 0C) until analyzed. All samples were analyzed for the mineral content by a trained technician of the Department of Pharmacology and Toxicology at Michigan State University. Sugar Analysis Glucose, sucrose, raffinose and stachyose were analyzed using High Performance Liquid Chromatography (HPLC) accor- ding to the procedure developed by Agbo (1982). The proce- dural diagram is presented in Figure 2. One gram sample of bean flour was mixed with ten ml of 80%(v/v) ethanol, shaken in a water bath at 80 0C for 15 minutes, and centrifuged for three minutes at 2000 RPM. The supernatant was collected in a separate tube. This extraction was performed twice more, with five ml and ten ml of 80% ethanol respectively. The supernatant from all three extractions was collected in the 36 1 gram of sample I Add 10 ml of 80 8 ethanol Shake in water bath at 80 C for 15 minutes Centrifuge at ZOOOIRPM for 3 minutes I j Residue A Supernatant A Add 5 ml of 80 8 ethanol Shake in water bath at 80 c for 15 minutes Centrifuge at 2000 RPM for 3 minutes L [ l Residue B Supernatant B I Add 10 m1 of 80 8 ethanol Shake in water bath at 80 C for 15 minutes Centrifuge at 2000 RPM for 3 minutes I [ l Residue C Supernatant C -—- Discard Supernatant A+B+C I Add 2 ml of 10 8 lead acetate Centrifuge at 2000 RPM for 3 minutes 1 I l Supernatant D Residue D Add 2 ml of 10 % oxalic acid Discard Centrifuge at 2000 RPM for 3 minutes L, I ”’1 Supernatant E Residue E Bring to volume with water Discard in 25 ml volumetric flask Prefilter with C18 Sep—Pak A Inject to HPLC Figure 2. Sample preparation for sugar analysis by High Performance Liquid Chromatography. 37 same tube and the precipitate was discarded. Then two m1 of 10% lead acetate were added. The extract mixture was shaken in the same manner and centrifuged at 2000 RPM for three Ininutes to precipitate proteins. The supernatant was re- moved and two ml of oxalic acid were added to it. The mixture was again shaken and centrifuged, and the final supernatant was brought to 25 ml with distilled water.‘ The solution was then filtered through an HA filter (Millipore Corp., Bedford, MA) and Sep-Pak C18 cartridge (Waters Asso- ciates, Inc., Milford, MA) and injected into the HPLC. The chromatography system was composed of a Solvent Delivery SystenI 6000 A, a Universal Chromatograph Injector U6K, a Differential Refractometer R401, and a Data Module 730 (Waters Associates, Inc., Milford, MA). The sample size was 25 microlitres and the solvent used was a mixture of 70% acetcuiitrile and 30% water (v/v) with a flow rate of one ml/miri. Resolution of sugars from this extraction was ac- complished by using a u—Bondpak Carbohydrate Analysis column (Waters Associates, Inc., Milford, MA). An external stan- dard Inethod programmed into the Data Module was used to identify and quantitate the sugars. Statistical Analysis TWHE "Statistical Package for the Social Sciences" (SPSS) COWPUter programs described by Nie et a1. (1975) for use on the CIR: 6500 computer operated by Michigan State University comPuterLaboratory was used to assist statistical analyses. 38 Multivariate analyses of variance and covariance were determined using subprogram ANOVA. Mean squares were reported after rounding. Single classification analyses of variance, Tukey mean separations and treatment trends were determined using subprogram ONEWAY. Tukey separations were presented such that treatments which were not significantly different (P 5 0.05) were indicated with like letters. Mean squares with significant F ratios were reported with probability levels of P 5 0.05 (*), P g 0.01 (**), and P g 0.001 (***). Coefficient of Variation (CV) which expresses the standard deviation as a percent of the mean was calculated (Little and Hills, 1972). RESULTS AND DI SCUSSION Two separate studies were undertaken in this research. Study I dealt with cooking preparation of beans at a fixed temperature of 190 °F (87.8 °C). Various soaking treatments were performed and cooking was done in two different ways: a) Blancher cooking, in which each sample was cooked in a separate flask in a blancher. b) Kettle cooking, in which all samples were cooked toge- ther in a steam kettle. In the blancher cooking section, the effects of soak time, soaking method, and cook time on physical changes (hydration ratio, shear force, and total solids) and chemical changes (protein, ash, minerals, and sugars) were investigated. In the kettle cooking section, the effects of soak time and cook time on shear force, protein, ash, and minerals were examined. Study II emphasized the effects of cooking temperature, as well as soak and cook time, on hydration ratio, shear force, and total solids in beans. Various soaking and cooking treatments were employed and the beans were cooked in separate flasks in the blancher. Four cooking temperatures; 181.3 °F, 190.7 CF, 200.0 OE, and 207.5 °F (82.9 °C, 88.1 °C, 93.3 °C, and 97.5 °C) were studied. 39 40 Physical and Chemical Changes During Preparation of Beans Blancher Cooking The effect of soak time, soaking method, and changes during the process of soaking and followed by cooking were investigated. Mean values and Tukey mean separations for physical and chemical characteristics of cold-soaked, hot-soaked, and cooked beans are presented in Tables 3, 4, 7, 8, 11, and 12. Graphical presentation of the results are in Figures 3 to 36 and the analysis of variance of the data for cooked beans of two different soaking methods are summarized in Tables 5, 6, 9, and 10. Hydration Ratio. For both navy and kidney beans, data showed insignificant increases in hydration ratio after 8 hours of cold soaking and after hot soaking (Figures 3 and 4). Hydration ratio increased more remarkably during the cooking period, with slightly higher ratios for 16-hour- soaked beans than for hot-soaked beans. Statistical analyses indicated the effect of soaking method and cook time as well as treatment interaction to be insignificant (Tables 3 to 6). The values of hydration ratio indicate the ability of beans to imbibe water. 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"mocmowuwcmwm mo Hm>wa aumawnmnoum mumofiocn .H 00H.H b00IN 0.0 000.N 0a0.0 0 >00 H00.0 000.0 0.0NAH H00.0 H00.0 0 0 Hmscwmmm 000.0 0N0.0 as 0.0000N at; 000.0 «a 000.0 H00.0 N PU x rm >m3I03e can vv0.0 0Nv.0 «ca 0.000vva «a. 000.0 «a. 00H.h N00I0 N .900 wfiwu x000 the 000.0 000.0 «a 0.00v0N at. 000.0 000.0 000.0 a .200 cocumE xmom ace 0Hd.0 NH0.0 «a. 0.00Hv0H «cc 00N.0 Hana 000.v 000.0 0 muumuuw 0062 :m4 cfimDOum ovuOu ummnm noun: an mcfiaon deuce momma ca mcwflom deuce owuou coMuoucaz moumsvm cam: 00 cowuuwum> mo mousom .mcumn x>ac mo acmuuuumoum madman nmmcaco Hm008020 can Huownxnm you oucmauo> uo m.m>~uc< .0 manna I46 aoc.c M a .I. H0.o W m as mc.c v a . "mocmowuficmmm uo Hm>oa aufiafianOum wumoflch .H 0Nv.a 000.0 >.v 04N.v 000.0 0 >00 000.0 000.0 0.0mHN 000.0 500.0 0 0 guacamom a v00.0 h00.0 t 0.00000 c 040.0 000.0 400.0 N 90 x :0 xmsIoze «ca 000.0 0N0.0 «an 0.0000NH «a; 000.0 «a. 000.0 N00.0 N .900 0&0» x000 coo 000.0 000.0 «a 0.00000 out v00.0 mvv.0 «00.0 a .20. vocuwe xmom ace 000.0 000.0 at. 0.00000 «ac 000.0 Hue. 00N.V 000.0 0 muowuum 0mm: nmd camuOum mouow umwsm noun: :0 wouaom Hmuoe ncmmn a“ moflaom Hmuoe oaunu cofiumu0>x moumsvm com: 00 cowumfiuo> no mausom .mcmmn amcowx uo cowuuummmum mcfiuav momcocu HmuMeono can Hoofimanm uOu oucumua> uo mamaamca .o canoe 47 cold-soaking and that soaking longer than 8 hours might not be necessary. In fact, soaking of more than 16 hours leads to microbial growth. 13331 Solids in Soaked and Cooked Beans. During the first 8 hours of cold soaking, the total solids in beans decreased dramatically but after that the rate of decrease slowed down until the end of the cold—soak period (Figures 5 and 6). A significant decrease after hot-soaking was also illustrated. The losses occurred more during cooking, with l6-hour-soaked beans showing greater losses than hot-soaked beans. The amount of total solids after 60 minutes of cooking was significantly lower than that after 30 minutes for both hot-soaked and 16—hour-soaked beans (Tables 3 and 4). Analysis of variance indicated the significance of treatment effects and interaction between soaking method and cook time for both bean types (Tables 5 and 6). Total Solids in Soak and Cook Waters. Total solids in soak water increased gradually over the cold-soaking period, but increased drastically after hot-soaking (Figures 7 and 8). Hot-soaked kidney beans lost more solids into the soak water than did hot-soaked navy beans. Total solids in cook waters were found to be much higher than those in soak waters (Tables 3 and 4). In addition, 16—hour-soaked beans lost more solids than hot-soaked beans during cooking. Analysis of variance showed significant effects of both soaking method and cook time. Treatment interaction effect ..m¢¢.wm n meadow Hmuou HmfiuficH. cofiumummoum mcfiusc mcmon >>mc cmxooo 0cm nmxmom c0 mowaom Hmuou mo momcmnu .0 musmfim 02:2. m2: xooo 650:. m2: x40... 00 00 00 0 0. v. N. 0. 0 0 v N o . _ . . q . _ _ _ . 48 SOI'IOS 1V10l W.) N? vv 0? 0v 00 N0 —\ x400 P0: IQI x<00 0400 IOI NV .Vv 0v 0? 00 N0 SOI'IOS 7V101 (WU 49 SOHOS 'IVIOJ. (°/o) 0v N¢ ¢¢ 0c mc 00 02:5 00 .AmHN.00 m5: x000 00 00 0 F\ q 4 _ x<00 P01 .IATI x400 0400 _IAYI mcfiaom Hmuou HmfiuwcH. coflumummoum mafiuso mcmwn moccflx cmxooo 0cm noxmom c0 mcwaom Hmuou mo momcmsu 0. c. N. .meOIv 0. _ 0.2.... x400 0 0 _ .0 musmwm 0v NV V? 0v 0v 00 SOHOS 7V101 (99 50 SOI'IOS 11101 (%J .10 0A. N4 0.. ON ¢.N 02:5 00 00 00 0.2.... 2000 0 J _ . . xcom ho: ILQI 2400 0400 IAYI 4>mc mo cowumnmmoum mcflucc mumums xooo 0cm xmom aw moflaom Hmuou mo mmmcmno .mmaoz. o. 0.2.... x<00 0 0 .w musmfim «.0 Q0 N.. 0.. ON ¢.N SOI'IOS 'IVIOJ. 0%) .mcmmn.>m:©fix mo coflumummwum mcwusc mumum3 xoou cam xmom cfi mowaom Hmuou mo mwmcmno .m musmwm ..z_z. m2: V68 .3305 ”:2: x48 0m 0m on o w. v. N. o. m w v N o 51 SOI'IOS 'IVLOJ. PM #0 0.0 N. 0.. 0.~ v.N x400 #0: IQI x<0m 0400 IOI ...<..r.z. _ 0.. 0.N TN SCI-10$ '"lVlOl (°/o) 52 in kidney beans was less than in navy beans (Tables 5 and 6). Shear Force. Significant effects of soaking method and cook time as well as their interaction were illustrated in both bean types (Tables 5 and 6). The beans were softer as the cook time increased (Tables 3 and 4) and hot-soaked beans were generally softer than l6—hour-soaked beans which were cooked for the same period of time (Figures 9 and 10). Protein Content. The protein content of raw navy beans was 23.3% (dry basis), which was slightly higher than the values in the literature of 21.4% (Watt and Merrill, 1963; and Meiners et al., 1976a). The protein of raw kidney beans was 29.9% (dry basis). This value was lower than the value reported by Koehler and Burke (1981) of 32.8%; but was much higher than the values of Watt and Merrill (1963) or Meiners et al. (1976a), which was 21.4%. Oneway analysis of variance showed that protein content did not change significantly during the soaking or cooking periods (Tables 3 and 4), although changes were observed in graphical presentation (Figures 11 and 12). There was a large increase of protein content after 2 hours of cold soaking. Actually this increase was due to the dry basis used in the determination of protein in soaked beans, in which dried bean flour samples were analyzed. All water was evaporated from the beans thus resulting in higher concen- tration of solids in them. The effects of both soaking 53 ON. .mcmmn >>mc mo cowumummwum mewuop mouom umwnm mo mwmcmnu .m musmwm 6332.2. m2; xooo 0m 00 on 0 a _ _ _ I. A x<0m P01 |A¥I J x<0m 0400 uAUI 00v 000 00m. 000. 000m 00vm 3380:! HVBHS (was '9 OOI/‘B'U 54 ON. .mcmmn amcpfix wo cofiumummmum mowusp wou0m ummnm mo mmmcmnu .ca musmfim 6332.2. 92; xooo om ow 0n 0 . _ q . «TI. x<0m k0: alVl 1 x<0m 0400 lOl . 00g 000 00m. 000. 000m 00vN 33805 HVBHS (was '9 OOI/‘B'U 55 (SISVB A80 °/o) NISLOBd MN VN 0N 0N 5N 0N ..z__2. .mcmmn >>mc mo cofiumummwum mcwuso ucmucoo cfimuoum mo mwmcmnu 00 on m2: x000 O T view so: I4! x400 0400 IAVI 45.22. 0. ¢. N. . $0001. 0. u 02.... x400 m 0 4 .HH musmfim MN cm 0N 0N hm 0N (susva A80 °/.) Nlaioad 56 (Slsva A80 °/.) Nlaioad am On mm mm ¢n .mcmmn wmccwx mo COwumummmum mcfiusc ucmucoo cfiwuoum mo mmmcmno ..z_z. 00 02:. 2000 00 On fl 2400 #0.... Id! x400 0400 IOI 45.22. 0. S N. .mmaoz. 0. m2: x<0w m 0 q .NH wuomwm N o - .. 4a 1 mm 1 0n 1 .m n Nm .3 L cm (Slsva A80 °/.) NIBlOHd 57 method and cook time were insignificant according to the analysis of variance (Tables 5 and 6). The results are in good agreement with those of Koehler and Burke (1981) and Haytowitz and Matthews (1983) who reported 93% to 100% retention of protein after cooking. However, they did not agree with those of Meiners et al. (1976a) who reported 50% to 60% loss of protein after cooking. Ash and Minerals. The ash contents of both raw navy and kidney beans were 4.1% (dry basis), which were in the range reported in literature of 3.9% to 4.8% (Watt and Merrill, 1963; Meiners et al., 1976a; and Koehler and Burke, 1981). Hot-soaking resulted in a greater decrease in ash content than did cold-soaking (Figures 13 and 14). Oneway analysis (Tables 3 and 4) showed greater loss of ash from cooking than from soaking, and hot-soaked beans lost more ash than did lG-hour-soaked beans. This was confirmed by significance of treatments and treatment interaction from the analysis of variance (Tables 5 and 6). The results were in accord with studies conducted by Watt and Merrill (1963), Meiners et al. (1976a), and Koehler and Burke (1981). The decrease in ash content is due to the leaching of minerals from beans into soak and cook waters. The values of nine minerals (Tables 7 and 8) in raw navy and kidney beans were reasonably consistent with values from previous studies (Table l). The calcium content increased during both soaking and 58 HSV (Slsve A80 °/.) 0.. 0.N 0.0 0.4 0.0 0.0 .25. 00 .mcmmn >>mc mo cofiumummmum mowuso ucwucoo 5mm 00 mmmcmno 0.2.... 2000 00 00 1 -O 2400 #0... ILQI 2400 0400 '0' 44.....2. 0. v. N. .mmaox. o. 0.2; 2400 0 0 .MH wusmflm — 0.. 0.N 0.0 0.4 0.0 0.0 HSV (SISVQ AUG °/o) 59 HSV (SiSVB A80 °/.) 0.. 0.N 0.0 0.4 0.0 0.0 ..z_:. 00 .mcmmn mmcnwx mo cOwumummmum mcfluoc ucwucoo 2mm 00 mwmcmno 0.2.... 2000 00 00 I Ill/d 2400 #0... I? 2400 0400 IO] 44.....2. 0. 4. N. .mmaox. o. 0.2.» 2400 0 0 _ .wa musmwm 0.. ON 0.0 0.4 0.0 0.0 HSV (Slsve A80 %) 60 cooking since beans absorbed water which contained 100 ppm calcium (Figures 15 and 16). In kidney beans, hot-soaked samples gained more calcium during cooking than did l6-hour- soaked samples. Both oneway analysis (Table 7) and analy- sis of variance for navy beans (Table 9) showed significance of soaking method and treatment interaction, but not for cook time alone. For kidney beans, the effect of cook time was more significant than soaking method and treatment interaction was not significant at all (Tables 8 and 10). Marked change in the copper content was not found in the entire process of preparation (Tables 7 and 8; Figures 17 and 18). From analysis of variance (Tables 9 and 10), cook time did not produce significant effect but the soaking method and treatment interaction were reported to be significant. Iron showed noticeable loss after soaking by either method as compared to the original iron content in unprocessed beans (Tables 7 and 8). Hot-soaked beans lost more iron than cold—soaked beans (Figures 19 and 20). Analysis of variance of navy beans (Table 9) indicated significant effects from soaking method and treatment interaction, but not from cook time. This implied that iron content in navy beans did not change significantly with the increase of cook time, but hot-soaked beans showed greater decrease during cooking than l6-hour—soaked beans. For kidney beans, neither treatment nor treatment interaction was statistically significant (Table 10). 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HVBHS (NVBG '9 OOI/'81) 101 explanation might be that there was a mass transfer between the bean and the cook water during cooking since all samples were cooked in the same cook water and container. Ash and Minerals. The ash content in both navy and kidney beans was significantly affected by soak time, cook time, and their interaction (Tables 15 and 16). The ash content in all navy beans cooked for 30 minutes was higher than that in beans cooked for longer time. The ash levels in beans cooked for 60 and 90 minutes were not statistically different (Tables 13 and 14). In addition, for the same length of cooking time, beans which were soaked longer showed greater loss of ash (Figures 39 and 40). The results of kidney beans followed a similar trend. Mean values and Tukey mean separation of all minerals are presented in Tables 17 and 18. The analysis of variance of all values are summarized in Tables 19 and 20. Cook time and treatment interaction effects were less significant than the effect of soak time on calcium content of navy beans. Whereas for kidney beans, all treatment effects were significant except the effect of treatment interaction. Calcium was found to increase rapidly in all cooked beans which were unsoaked or soaked for 8 hours; but for cooked beans which were soaked for 12 and 16 hours, the increase was not statistically significant. However, oneway analysis indicated that all reported values were not statistically different. The change in copper content in 102 .mcmmn >>mc mo coHumumomuo mcHuoO ucmucoo own no mmmcmno .mm wuomHm .9501. m2; x HHO .N ..mo.o v m. mmocONOOOHO ucooHuHcmHm oc mumoHOcH casHoo sumo cHnqu muouuoH mxHo .H m NmooH m N.hN m «Omv a H.0N m O.mH n NHmH a o.MO a O.m o amON mmuscHE cm a mnooH m 0.0N no Hahv a m.NN m H.mH m NOmH m o.HO a o.OH a OoON mouscHE 0O 0 NNmNH m O.mN n Ommv m v.Hm m o.mH m hOmH m O.om n 0.0H m OOON mmuocHE om xmom muson OH m momm m «.ON 8 Ommc a m.pN m o.mH m vaH a o.mn m n.m m «NON mouscHE ca 8 Oomm m N.¢N m Hmme m O.vN m O.~H m HMNH m O.m5 m m.O a NovN mmuscHE cm a omNNH m N.ON m OOOO m v.mN a m.mH a MOmH m H.mh m b.0H m thN mwuscHe on xmom muson NH 8 OVOOH m m.ON m OOOv a O.NN m m.mH a mmmH a >.mh m m.m a mth mouscHE cm a oomHH m c.5N m mvmv m H.5N m o.o~ m OOMH m N.NO n m.oH m OOON mwuscHE OO 8 OmHNH m m.¢N m «HOc m N.mN m N.OH a HOMH m H.bh no N.oH m vaN mwuocHe om xmom muse: O m vhHHH n H.ON n ovmw a O.on m O.mH a OONH m m.nn m 0.0H n vnNN mouscHE co m thcH om o.eN m nvmv m o.ON m m.>H a NVNH a N.mn m H.oH n ONHN mwuscHE OO 8 OOFMH a O.NN m mmvx m m.ON m h.OH m OHNH m O.Nb 8 «.OH m HOOH mmuscHE on mAOcmmn 3ou. xoom noon 0 a an m oz :2 m: on nu no oeHu xooo N.H.ncmmn a>mc uo coHuaquOHQ mcHusc acoucoo HmuwcHa mo momconu .hH mHnme 105 .meuNNNQOm ococ no: maHu xmom comm uou coHumumoom some No.29 .m ..mHmmn Ono. coHHHHe boo muumo cH mum mosHm> HHO .N ..mo.o W m. mmucoNouuHO ucmuHuHcmHm oc wumoHocH cEsHoo comm chqu muOuuoH mxHo .H m vHNOH m O.Nm w thv a o.vm m O.mH m HOHH m N.OO m o.O n OHOH mouscHE cm 2 HNNHH a N.Hm m mmqv m 5.5O a H.OH m NOHH m O.Nm a m.O no vaH mmuocHe 0O 0 OOONH m O.om m «Owe m q.mm m ¢.mH m HONH m N.OO m 0.0 m NNOH mouscHe om xmom mono; OH w ooHOH m m.NO o Ova m «.mw n N.¢H n OwHH m 0.0m m o.O m OOOH mmuocHe om m OOOHH m N.Hm m OOmv m O.ov n h.vH m OOHH m h.mm m o.» m mHOH mouscHE OO O NOONH m ¢.om m morv m H.Om n m.mH m OONH m h.OO m v.O m mmnH mmuscHE om xmom muson NH m NOOoH n N.NO m mmmv o N.¢m m O.¢H m ONHH a 0.00 m O.m a omOH mmuocHe cm 8 OHHHH m N.Om m OOOv m H.Om m H.OH m NOHH m o.vm a h.m m «OOH mmuscHE OO O ONOHH m O.om o vOOq m O.om m o.OH n mmNH m H.OO m H.O a ONOH mouscwe om xmom mason O m «HHNH m N.mm m ovhv m O.ov m N.mH m hHNH a v.5m n N.O m OOOH mmuscHE cm 8 OONOH m m.Hm m Nan m m.mm n m.¢H m OONH m o.OO m 0.0 a HomH mmuocHe OO O ONaqH m O.mN a Ova m v.vm m O.nH m OONH m 0.00 a v.O m OmmH mmuscHE on n.mcmmn 3mm. xmom use; 0 x cu m oz c: m: mm 90 no me.» .000 N.H.mcamn aocOHx uo coHumumomuo mcHusO ucmucou HauocHE mo momconu .OH oHnoa 106 :56 M m 2... H0.0 W m xx O0.0 v m a "oocooHuHcon uo Ho>oH auHHHnNOONQ ouaochH .H NOv.m OOm.n O.m N¢o.HN HOO.v O.m Hha.n th.n O.' >0» so+m HNH.o OOO.H o.HOOON OhN.ON vmh.o O.HNHN OO0.0 nNH.o h.vOHvH NH Hoochoz ha+m NOH.o Ohn.H h.OONOO NNH.ov Nah.o H.OOvO Oha.oH c hom.o a 0.000>O O 90 x em aoanoze a. OO+O vOm.o . NON.O O.HNHON vvm.o OON.N N.OOON Ohm.mH cc ONo.H . H.vONOn N .eu. aaHu xooo .. ncxm vvs.o a. mvh.O N.OmHmm Hmm.m c NON.O .. H.OOOOH x OO0.00 Ohm.c ... o.OOOOOv M .9m. we.» xoom .- ho+m OvO.o a. OO0.0 v.NmOnv OHN.N c ONO.N ax o.OONNH . OO0.00 ax On0.0 H... O.hOvaO O maoouuo :Ho: s. as a oz 5. m: on so no «amazon can: an coHuNHun> Oo ocuaom .mcmoa a>oc uo coHauuaomuo mcHuoo acoucoo Houoc.a Oo momcnzo you oucaHum> uo mmeHch .OH «Hook 1()7 "cocooHuHcoHa uo Ho>oH Hoa.o M a ... Ha.c N N .. m°.o v N . auHHHnonouo auaoHccH .H m.n OOO.N N.n OO0.0 OON.N m.N ono.n oHv.O n.n >0a o.ONOOhH vOO.o ¢.thNN Onn.O aao.c H.ONNH OHo.n HOH.o H.OONO NH HonoHuoz 0.0anHH vom.o n.OmOOH OOO.NH cc Hms.o n.Ohn nhH.H OOH.o o.OnNO O 90 x am aoznoxh .o. ~°+O an.c ac. OON.OH 0.00000 OON.HN a. OO0.0 ccc «.OODNH vov.O ovn.o a. o.OHnNn N .90. 03H» xooo cc. so+m OOO.o OOo.c v.ovOOH ccc Nan.vO ONH.o n.NnnH OOO.nH Omn.c cc. v.OOnOOH n .pm. 02.» xoom cc. sc+u vma.¢ . HvH.v m.aomOn a. onn.pv a Hmn.c cc O.vaO FN~.NH mhn.c H... h.HOO¢NH m mucouuo cH-z x as a oz :2 m: on so an monsoon coo: uv oucoHua> no cannon .acoon aochx no coHuauooouo ocHuso accucoo HauocHl no someone new oucaHun> uo anaHact .ON OHnaa 108 both bean types was not significant. In navy beans, analy- sis of variance showed moderate significance for all treat— ment effects and treatment interactions except for effect of soak time. But the effects of treatment and treatment interaction were not significant for kidney bean c0pper content. Iron values in both bean types did not differ statistically. This is supported by the analysis of vari- ance which showed only small significant effect of soak time on the iron content of both navy and kidney beans. The results revealed that there was no marked change of iron during cooking. As for iron, magnesium in both beans showed no significant change during cooking. However, magnesium content was moderately affected by soak time in the case of navy beans, and was significantly affected by treatment interaction according to the analysis of variance. The change of manganese in navy beans during cooking was also found to be negligible and similar results were reported for kidney beans. The analysis of variance revealed moderately significant effects of cook time and treatment interaction on the amount of manganese in kidney beans. A slight effect of soak time was also detected in navy beans. Oneway analysis for sodium, phosphorus, and zinc indi- cated no significant changes of these elements in both bean types during cooking. This was also shown for potassium except in cooked beans soaked for 16 hours. Potassium decreased significantly with the increase in cook time. 109 Analysis of variance of navy beans indicated insignifi- cant effects of treatments and their interactions on sodium and phosphorus contents, but treatment effects on zinc and potassium were moderately significant. In kidney beans, soak time had meaningful effect on sodium, while zinc was affected by cook time. Phosphorus was not affected by any of the treatments, but for potassium, both treatments and treatment interaction were significant. When comparing the mineral contents of beans soaked for 16 hours and cooked for 90 minutes from blancher cooking and kettle cooking, it was found that for kidney beans, all values from blancher cooking were higher than those from kettle cooking. However, for navy beans, most values were close except for sodium, potassium, and zinc, which were lower for kettle cooked beans than for those from blancher cooking. Cooking Temperature Effect on Physical Characteristics of Beans Each sample of beans was cooked in a separate flask in the blancher. The effects of cooking temperature, soak time, cook time, and their interactions were investigated. Mean values and Tukey mean separations are presented in Tables 21 and 22. Analysis of variance are summarized in Tables 23 and 24 and Figures 41 to 46 are graphical presen- tation of all data obtained from the study. 110 Table 21. Bffect of cooking temperature on physical characteristics of navy beans.1 Cook time Hydration ratio Shear force2 Total solids in water3 cooxxuc TEMPERATURE 181.3 °P (82.9 °C) 0 hour soak (raw beans) 30 minutes 1.64 a 1650 c 0.54 a 60 minutes 1.76 b 1245 ab 1.42 cd 90 minutes 1.85 be 1095 ab 1.69 sf 6 hours soak 30 minutes 1.78 be 1320 b 1.23 b 60 minutes 1.83 bc 1110 ab 1.51 de 90 minutes 1.83 bc 990 a 1.70 f 12 hours soak 30 minutes 1.84 bc 1320 b 1.24 be 60 minutes 1.87 c 1065 ab 1.51 de 90 minutes 1.87 c 998 a 1.71 t COOKING TEMPERATURE 190.7 02 (88.1 °C) 0 hour soak (raw beans) 30 minutes 1.59 a 1680 d 0.71 a 60 minutes 1.76 b 1118 c 1.49 bc 90 minutes 1.82 bcd 773 ab 1.72 do 6 hours soak 30 minutes 1.81 be 1095 c 1.32 b 60 minutes 1.87 ed 750 ab 1.62 cd 90 minutes 1.91 cd 500 a 1.89 of 12 hours soak 30 minutes 1.89 ed 915 be 1.36 b 60 minutes . 1.91 ed 735 ab 1.72 de 90 minutes 1.93 d 595 a 1.96 t COOKING TEMPERATURE 200.0 °P (93.3 °C) 0 hour soak (raw beans) - 30 minutes 1.56 a 1680 d 0.92 a 60 minutes 1.76 b 795 be 1.56 b 90 minutes 1.88 bed 538 abc 1.83 bc 6 hours soak 30 minutes 1.85 bc 840 c 1.34 ab 60 minutes 1.93 cd 485 abc 1.65 b 90 minutes 2.02 do 370 a 2.18 c 12 hours soak 30 minutes 1.92 cd 698 abc 1.50 b 60 minutes 1.97 cde 498 abc 1.76 bc 90 minutes 2.10 e 415 ab 2.20 c COOKING TEMPERATURE 207.5 °P (97.5 °C) 0 hour soak (raw beans) 30 minutes 1.67 a 1185 d 0.93 a 60 minutes 1.86 ab 590 c 1.63 be 90 minutes 2.09 cd 313 ab 2.30 d 6 hours soak 30 minutes 1.87 ab 555 be 1.51 b 60 minutes 2.15 d 310 a 1.75 c 90 minutes 2.15 d 293 a 2.41 d 12 hours soak 30 minutes 1.89 bc 600 c 1.51 b 60 minutes 2.03 bcd 390 abc 1.77 c 90 minutes 2.16 d 305 a 2.50 d 1. Like letters within each column indicate no significant differences (P g 0.05) and Tukey mean separation within each group of cooking temperature was done separately. 2. Shear force is expressed in pounds per 100 grams of bean. 3. Total solids in water is expressed in per cent. 111 Table 22. Effect of cooking temperature on physical characteristics of kidney beans.1 Cook time Hydration ratio Shear force2 Total solids in water3 COOKING TEMPERATURE 181.3 °P (82.9 °C) 0 hour soak (raw beans) 30 minutes 1.46 a 2055 f 0.45 a 60 minutes 1.65 b 1440 e 0.94 b 90 minutes 1.79 c 1230 cd 1.49 cd 6 hours soak 30 minutes 1.93 d 1260 d 1.05 b 60 minutes 1.96 d 1170 bcd 1.50 d 90 minutes 1.96 d 1110 ab 1.83 cf 12 hour soak ' 30 minutes 1.95 d 1238 d 1.28 c 60 minutes 1.96 d 1133 be 1.63 de 90 minutes 2.00 d 1020 a 1.94 f COOKING TEMPERATURE 190.7 0? (88.1 °C) 0 hour soak (raw beans) 30 minutes 1.44 a 2010 f 0.62 a 60 minutes 1.64 b 1380 e 1.01 b 90 minutes 1.78 c 1095 cde 1.53 d 6 hours soak 30 minutes 1.91 cd 1140 de 1.12 b 60 minutes 1.94 d 825 abc 1.53 d 90 minutes 1.94 d 610 a 1.85 s 12 hours soak 30 minutes 1.98 d 953 bed 1.35 c 60 minutes 1.98 d 733 ab 1.63 d 90 minutes 2.00 d 663 a 2.00 f COOKING TEMPERATURE 200.0 °P (93.3 °C) 0 hour soak (raw beans) 30 minutes 1.32 a 2220 d 0.57 a 60 minutes 1.53 b 1680 cd 0.83 b 90 minutes 1.58 b 1320 bc 1.01 b 6 hours soak 30 minutes 1.91 c 945 ab 1.22 c 60 minutes 1.94 c 625 a 1.61 de 90 minutes 1.99 c 490 a 1.88 £9 12 hours soak 30 minutes 1.99 c 735 ab 1.43 cd 60 minutes 2.03 c 533 a 1.70 ef 90 minutes 2.08 c 450 a 2.06 g COOKING TEMPERATURE 207.5 °F (97.5 °C) 0 hour soak (raw beans) 30 minutes 1.71 a 1358 d 0.64 a 60 minutes 1.73 a 1083 c 1.37 be 90 minutes 1.87 b 678 b 1.48 bc 6 hours soak 30 minutes 1.97 c 585 b 1.27 b 60 minutes 2.09 d 355 a 1.71 bc 90 minutes 2.13 d 340 a 2.34 d 12 hours soak 30 minutes 1.98 c 615 b 1.45 bc 60 minutes 2.08 d 403 a 1.88 cd 90 minutes 2.13 d 395 a 2.34 d 1. Like letters within each column indicate no significant difference (P g 0.05) and Tukey mean separation within each group of cooking temperature was done separately. 2. Shear force is expressed in pounds per 100 grams of bean. 3. Total solids in water is expressed in per cent. 11.2 Hoo.o M m xxx Ho.o W m xx mo.O v m x ”mocmoHOHcmHm no HO>OH quHHnmnouo mumoHOcH .H HvO.v O.m NOO.H >Uw Ooo.o N.OMNO Hoo.o Om Hmovawm 0Ho.o x ¢.vOOMH Noo.o NH BU x 9m x E Nasnomuze xxx OOH.o xxx O.mmhmOH xxx OH0.0 v «Emu x000 x OEHu xmom xxx Ono.o xx m.¢mOHN xxx hHo.o O OEHu x000 x Ouaumummewa voo.o xxx N.VOOHM xxx OHo.o O mEHu xmom x muoumuwmfimfi >m3uoze xxx OOH.v xxx hoxm hhH.O xxx ONN.o N .80. 06H» x000 xxx hOh.o xxx N.OONth xxx OHN.O N HBO. 08H» xmow 4.. x>m.o 4.x ~o+m mmH.o xx. «HH.o m .9. musbmuomsme xxx hOO.H xxx ho+m mvH.o Hxxx OBH.O b muomuum CHM: uwum3 CM WUHHOW HMUOH. COMO“ Hflmfim OMUNH COM&MHU%: mmunsvm cum: no coHuOHua> mo Ovuaom .mcmon >>mc mo coHumumowum mcHusO momcano Hmonxnm uOu mocmHum> uo mHmaHch .mN wHowe 1.13 Hoo.o M a ... A0.0 W m xx mo.o v a . "wocmoHuHcmHm Oo Hm>wH auHHHnmnouo mumoHOcH .H th.O v.m HOO.H >0» Ooo.o m.OOhO Hoo.o Om HNOOHmmm xxx NNo.o N.OHHm xxx moo.o NH 90 x 9m x 9 Omsnmmuze NHo.o xxx v.HOemmH xxx ONo.o v OEHu .000 x 02H» xmom xx. emo.o m.mmHOH ooo.o O 05H» .000 x mssumummeme xxx mmo.o xxx 0.0HOO>H xxx NNo.o O OEHu xmom x musumuwaewe >m3uoze xxx VHO.m xxx ho+m ovH.o xxx OHH.O N .80. wEHu x000 xxx Ohm.m xxx ho+m Nam.o xxx NOH.H N APO. wEHu xmow xxx OON.O xxx ho+m ONH.O xxx Oho.o m .9. musumummemb xxx «OH.N xxx so+m hON.o Hxxx NOm.o h muowuum chz umums cH mOHHom choe mouou ummnm oHumu coHumuON: mmumsvm cam: NO coHumHum> mo Ocusom .mcmon NocOHx uo coHumummmum mcHusO mwmcmnu Hmonhsm now mocoHum> no mHmszcd .VN oHnme 114 3.0' 2.5 P to. D——————jr————‘j:::::: (O) T i LO '- -O- 30 Ill COOK + .0 I04 COO“ 05 '- -O- 00 III COOK c ‘ ‘ ‘ ' no no no 200 2.3 TEMPEIATURE 1") SC r 25 r o 2: - < 8 8 ‘ D (b) ;_— - ¢ 2 O p I : ~ --0— so am com -6- 60 MIN COOK c: - ..0_ so am coox “.7; no: I90 2:20 2 O TEHFERATUIE PF) 3: - 2: . 9 2: - é a 5 5— - 2 (C) 9 5 b h < E ‘;.' I 7. .. -O- 30 um COOK —b— 60 am 000:! c e - Ho— so am COOK : ‘ L * ‘ 7; Is: no 20: 2 o TEMPERATURE PF) Figure 41. Cooking temperature effect on hydration ratio of navy beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak. 115 2.5 '- (0) HYDRAYION RATIO 0 V '~° ' -o- 30 um cock -6— CO “IN COOK CS - -D- so am coon c ' J. l I 170 IIO 190 200 2:0 TEMPERATURE PF) 30 - 2: - 9 2: v- : E :H s z (b‘ 9 5 - ‘ a o ’- x I: - -O— 30 IIN COOK + ‘0 “m COOK :: t - -O- 90 um COOK c ‘ * 1 ‘ ITO ISO IOO 200 2'0 TEMPERATURE i") 3: r 2‘.‘ > -i_-—-———- 9 2: b W #1.: E z (c) 9 5 - 2 2 o ,- x C r- -0- so am cook —6— 60 um COOx :: ,. c4 )— .O “IN COOK c ‘ v n ‘70 180 (90 230 2! TEMPERATURE ('6) Figure 42. Cooking temperature effect on hydration ratio of kidney beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak. 116 2400 P -O- so mu coax - sooo - .0. so mu coo: 8 < 3 -O- » Mm coon . A " IsOO ~ 0 V O O I 0' :3 (a) two - U U 8 0 Is ¢ sOO ~ C U I 8) OOO - o r L L I no no no zoo zno Trunanunr PF) 2400 F -O- 30 um. cock ‘5 2000 r + so we coax ( 3 -0- so am, coon: 0' 0 mac > . O I O“ :1 (O) Izoo » U U I 0 lb 3 .0: " C U I 0) 4c: - c ' J 1 . no use use zoo 2:: TEMPERATURE (on 2400 - -O- 30 um COOK __ zooo - -A— 60 um COOK 8 g -0- ’0 lm COOK : IGSC b O 2 o‘ :3 (c) IZOC . U U C O h u so: - C U 2 In no: - o L i L ' ‘70 no use 200 2.: TEMPERATURE Pf) Figure 43. Cooking temperature effect on shear force of navy beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak. 2400 P __ zooo - 2 ( U a d 0 I300 . 2 \ o' :1 (o) uzoo - U U 3 IL 5 '00 ' -0- so um. coo-t U 55 -o— co um. coon ‘00 - -0- so am. coon O7 1 1 1 , ' ° '00 no zoo zuo TEupEu'runE PF) 1‘00 ’ -0- so am coo-x ‘2‘ zoo: - -6— so am coox ( 3 -o- oo um. com: 3' .m _ , 9 ‘. O :1 (b) uzoo . U U I o In t GO: >- ( U 2 In ‘03 u- o 1 1 l J 170 :00 I90 200 210 TEM’ERATUIE Pr) zczo . -0- so am. coo: zoo: - --6- so am coo: -O- 00 um coon: I630 - (C) 12:. » SHEAR FORCE (La/loo 6. arm) :J O a 0 5 O N 0 () n u YEMPEIATURE PF) Figure 44. Cooking temperature effect on shear force of kidney beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak. 118 Analysis of variance illustrated significant effects of all treatments as well as most of the treatment interactions on the hydration ratio, shear force, and total solids in cook water of both navy and kidney beans. In Figure 41, the difference of hydration ratio between unsoaked and soaked navy beans was obvious. Hydration ratio did not increased markedly with increased cooking temperature. The effect of cook time on hydration ratio decreased as beans were soaked longer, which implied that after a long soaking, beans did not absorb more water as the cook time increased. Effect of soak time on hydration ratio was less after six hours of soaking. Unsoaked kidney beans absorbed remarkably less water than did 6-hour— and 12-hour-soaked beans (Figure 42). Kidney bean results were similar to those of navy beans except at the cooking temperature of 200 °F (93.3 °C), where all unsoaked kidney beans showed a hydration ratio reduction. Shear force generally decreased with higher cooking temperature (Figures 43 and 44). In beans cooked for the same period of time, unsoaked beans were significantly “firmer than the other two groups. All unsoaked kidney beans cooked at 200 °F (93.3 0C) were found to be the toughest. For soaked navy and kidney beans, the effects of soak and cook times on bean texture were less as the soak and cook times increased. Beans tended to lose higher amounts of solids into the cook water as the cooking temperature increased (Figures 45 and 46). Again, the dif- ference between unsoaked and soaked beans was very obvious. 119 For navy beans cooked for the same length of time (Figure 45), the loss of total solids did not increase significantly after six hours of soaking. All unsoaked kidney beans cooked at 200 °F (93.3 °C) lost markedly lower amount of solids than did those cooked at other temperatures (Figure 46). Soak and cook times had more effect on solid losses of kidney beans than on those of navy beans. It should be noted that the results of unsoaked and cooked kidney beans at 200 °F (93.3 0C) were very consis- tent. The hydration ratio dropped, the beans were firmer and leached out fewer solids than beans cooked at lower or higher temperatures (Figures 42a, 44a, and 46a). It was clearly seen from visual observation as well that these beans were wrinkled and had not absorbed much water. In addition, longer cook time did not appreciably improve the texture or water absorption capacity of these beans. In conclusion, cooking temperature produced significant effects on bean texture and solid losses, but had little effect on hydration ratio. Elevated temperatures as well as prolonged soaking and cooking resulted in softer products but also greater loss of solids from beans. The decrease of bean firmness by increasing the cook- ing temperature was also interested. Shear force values of cooked beans were plotted against cooking temperatures on semi-logarithmic scales as shown in Figures 47 and 48. Regression equation for each line was calculated (Tables 25 N (O) YOTAL SOLID. (b) touL some: m 101“. souos m Figure 45. 120 30 ' .0- 30 III COM 1 5 P + ‘0 ‘1! COO“ -D- .0 I!” COO“ 2.0 * L5 D W I O '- 0‘: p //——_o o l 4 l L) ‘70 I30 ICC 200 ZIO TEqunnunE ('F) 30 P -0- so Im. COOK 2 5 ' -6— .0 II“ C00“ ‘0" .0 III COOK 2 O '- L5 b w ID > 0 5 '- 0 ' 1 1 ' I70 IOO I’D 200 2'3 TEMPERATURE PF) 30 .- -0- so um COOK 2 5 " + ‘0 '1” COO“ -D- .0 III. C00“ 2 O '- l 0 ' 0 5 '- o L L l :70 IIQ ISO 200 2:0 YEM’ERATURE P') Cooking temperature effect on total solids of navy bean cook water with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak. 121 30 P —O— 30 III C00“ 23 b '6' OO III COOK —O— 00 com com: Z 20- C 9 J (a) 8 "5 ' J C .- O P ‘O b 0.5,. O/‘M’o o L l l g I70 IOO IOO ZOO ZIO TEI'ERATUR! PF) 30 - -O- 30 III COOK 2 5 " + ‘0 ll“ COO‘ -O- 00 um cool: 2 20'- . U 9 / .J A (b) a '5 b €+——* — J ( .- 0 0M4 0- IO- 05- o 1 l ' J I70 IIO ISO 200 2|: TEM’EIATURE PF) 33 r -O- so am com 25’ .6— ‘0 “I“ COOK -o- ”W __ 23 > 1‘. "‘ b—/ 9 J (C) 8 '5 - J W C p- O .- Io b 05- O ' ' 4 37: I00 ISO 233 2‘3 TEMPERATURE PF) Figure 46. Cooking temperature effect on total solids of kidney bean cook water with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak. 122 ”O E b -0- so In: coo. ‘ ' '6- co mu coo- - F g _ '0- 00 In: coo. ;' . o 2 _ \ o' 9 n =3 ' (o) aooo C A U h 0 b § ~ 0 b c ‘ v- E Q .- uoo I I J , no no "0 300 no MOE timing”: (In _, -O- no I"! coo: )- )- -o- so am coo. '3‘ i ,_ -D- .0 In: COD! 0' o )- 2 ‘. 3 (N " IOOO : U r- ‘s‘ L P b b a g p 3 . b 1°C 1 J 1 J "O 0.0 I’D 10C ZIC YEI’HATUIE fr) IOOOC E r- -O- ’0 .'~ COC- b ,. + CO I». COD! '5 3 '- --0- 0o an. coo- a e b o 9 \ 3' \‘i (c) '- loo: ~ p U I- U . D o p c b p 3 )- f 0 )- h ‘0: l J 1 IVC ICC ISO 200 2 3 TIIFLIAYJIE PF) Figure 47. Z—value evaluation of navy beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak. 123 0.000 E I : -0- oo In coon ’ + co um coon b E _ -O- 00 In: coon 8 .. P o g No\ ‘. O (o) 3'- |ooo : A o U L- g .- b )- D 3 r E q :- IOO J 1 l 1 070 .0 I” 200 RIO "mow-c en .mo E .. -0- co um coo. h + co um coo“ .. L- : b -D- .0 Im ‘00:: a . o h- o 2 § 3 (b) "’ IOOO : I! U C 8 r b *- D c ‘ In ¥ a » Ioc ‘ l 1 4 no no no too 2:: flan-nun: (m uoooc . : -0— so In. coo: .. + CO Im COO-A I:- L -O- .6 "N COO! '1 L. U G 6 P o o I 3 (c) - nooo : U \- g h- e . ). z r U x a— 0 P- )- Ioc 4 4 ’ ’ no IIC use 20C z-c TII’E'AYUIE t") Figure 48. Z-value evaluation of kidney beans with various processing conditions: (a) no soak; (b) 6 hours soak; (c) 12 hours soak. 124 .ufimccounmm moumoc a“ commoumxo mfl osam>nm .N .ufioncounmm owummp c“ musumuomEou mcfixooo mnu mucomoummu e .osHm> wou0m ummnm mo moH may mucmmoumou m .H hmm.am a ahwmmao.o momhmmv.w n m mmuscfle om mmv.¢m B hmammao.o ommomho.m u m mouscfie ow vmv.oh a nanomao.o eoomwhv.m u m mou:CwE om xmom muson NH bom.om a mmvomao.o Haommom.o u m mouscfia om Hum.>v a mmwmomo.o emaavmm.m u m mouscfle om mmw.an a mmmmmao.o omaoohm.m u m mouscfie om xmom muse: m Hao.mv 9 homaomo.o mommma>.w u m mwuscfia om www.mm B Neaomao.o mmvmaav.m n m mmuscfle om mmm.va~ a mvmmvoo.o hmmmmmo.v n m mouscfie om Anamon 3muv xmom noon 0 ~n\H u N Hen m n m men» xooo .mcmon >>mc mo mosam>uN .mN wanme 125 .uflmccoucmm moumop cw pommmumxm ma wsam>IN .m .ufimscwunmm omumwp cg musumuomEou mcfixoou on» mucomoummu 9 .msHm> m0u0u ummnm mo 00H onu mucwmoummu m .H vHN.Nm 9 mmnooao.o mammaom.m u m mouscfie om v5a.mm a mammoao.o moammoa.m u m mouscfie om mH¢.mm a mmmwaao.o mahvmma.m u m mouscfie om xmom muse: ma Hun.mm 9 mnmmmao.o mmhhmmm.o n m mouscfle om NmH.mm a wmommao.o mommom¢.o u m mouscfle om Hm~.mm e Hwaomao.o qmmmmam.m n m mwu:CwE om xmom muso: m wom.mva e >mm>moo.o mmmamem.w n m mouscfle om www.mmm e mmemmoo.o memmman.m u m mmuscfie ow www.mma e mmommoo.o Haqmmom.v u m mouscfie om Anamon smuv xmom use: 0 ND\H H N H93 0 H m @Ewu X000 .mcmon >ocpflx mo monam>um .mm magma 126 and 26). The Z-values, which are the increase of tempera- ture required to reduce the firmness or shear force values of cooked beans by 90%, are the slopes of the regression lines. The results showed very high z-values for unsoaked and cooked navy and kidney beans. In beans of the same soak treatment, Z-values decreased as the cook time increased. Davis (1976) suggested that one should increase cooking temperature instead of cook time in order to obtain a de- sired texture of navy beans. From the current study, if a specific cook time is to be maintained, an increase of cooking temperature of at least 50 °F (27.8 0C) is required to soften the beans by 90%. SUMMARY AND CONCLUSIONS The objective of Study I was to investigate physical and chemical changes in navy and kidney beans during cooking preparation. Results from both blancher cooking and kettle cooking revealed that beans should be either hot-soaked or cold—soaked for at least eight hours prior to cooking. Beans became softer as the cook time increased. No changes in shear peak configuration (Type A or Type B, Hosfield and Uebersax, 1980) were observed under different soak and cook conditions. All conditions showed predominant compresssion peaks (Type B). It was found that chemical changes in beans during soaking were not significant when compared to the changes occurred in cooking, and that hot-soaking generally resulted in greater changes than cold-soaking. Protein content did not change significantly during preparation. Most minerals showed remarkable decreases except for calcium, copper, and sodium. Potassium showed the greatest losses of 31% to 45% followed by magnesium, phosphorus, zinc, and manganese. Again, the decrease occurred more during cooking and the changes were greater as the cook time increased. Sugars also showed substantial losses during cooking. It was shown that hot-soaking of navy and kidney beans resulted in 30% and 39% reduction of sugars of the 127 128 raffinose family, respectively, while l6-hour-soaking re- moved 35% to 50% of these sugars from both bean types. When cook time of 90 minutes was applied and the cook water was discarded, 62% to 80% decrease of these sugars occurred. It was concluded that discarding the soak and cook waters provided both positive and negative results, i.e., the unde- sirable sugars were removed but valuable soluble minerals were also discarded. The effect of cooking temperatures, as well as soak and cook times, were evaluated in Study II. It was shown that cooking temperature and time did produce significant effects on both bean texture and the amount of solids leached out into cook water, but their effects on hydration ratio were less significant. Soak time, on the other hand, played a less meaningful role on all physical changes in beans than did the cook time and cooking temperature. In this study, the Z-values for bean texture were also calculated and it was found that in order to decrease 90% of the bean firmness, an increase of cooking temperature of at least 50 °F (27.8 °C) was required for both bean types. APPENDIX APPENDIX CALCULATION OF SOAK AND COOK WATER PREPARATION The soak and cook water used was distilled water con- taining 100 ppm of calcium. Calcium chloride (CaClz) was added to yield the desired hardness. Molecular weight of CaC12 40.08 g Ca++ + 2(35.5) 9 C12 = 111.08 9 Percent Of Ca++ in CaC12 = 40i0§.§8100 = 36.08% The desired hardness of water was 100 ppm, that is, one kg of water contains 0.1 g of Ca++. 0.1 X 100 36.08 CaC12 needed to get 0.1 g Ca++ 0.28 9 Therefore, one kg of water required 0.28 g of CaC12 to obtain 100 ppm of calcium. 129 L I ST OF REFERENCES L I ST OF REFERENCES AACC. 1983. "AACC Approved Methods," 8th ed. American Association of Cereal Chemists. St. Paul, MN. Agbo, N.G. 1982. 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