117 914 THE EFFECT OF KIND AND CGNCENTRAUON OF SUGAR ON GLUTEN FORMAHW AND CHARACTER Thesis {or “is Dag?“ of M. 5. MICHIGAH STATE UNIVERSITY Donna Poland Meiske 1957 This is to certify that the thesis entitled The Effect of Kind and Concentration of Sugar on Gluten Formation and Character presented by Donna Poland Meiske has been accepted towards fulfilment of the requirements for Master of Sciemaegree in Foods and Nutrition Major Zrofess; Date May 23. 1957 THE EFFECT OF KIND AND CONCENTRATION OF SUGAR ON GLUTEN FORMATION AND CHARACTER by Donna Poland Meiske AN ABSTRACT Submitted to the College of Home Economics of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Foods and Nutrition 1957 Approved %4 )7] flay-”M LIBRARY Michigan State University Mr AN.ABSTRACT DONNA POLAND MEISKE The effects of various sugars on gluten formation and character were studied before and after heat denaturation. An all-purpose flour was used throughout the study. Two experimental procedures were employed. lrithefirst procedure 5% levels of D (-) fructose C.P., D (-) glucose C.P., beta-lactose 98%, D (+) technical maltose, or sucrose (cane sugar) were incorporated in: (a) a dough in the preparation 0f gluten, (b) gluten prepared from the above method, and (c) gluten prepared from only a flour-water dough. The effects _Of the three methods of adding the sugars and the effects of each sugar on gluten were determined by measuring the amount of resulting drip loss obtained from raw gluten, and the vol— umes and crushing forces of baked gluten balls. Gluten which had had no sugar additions served as a control for each method. Drip losses of gluten were greater when sugars were in- corporated in gluten after preparation. These drip losses in addition to containing some of the added sugar in solution were shown to include nitrogenous material (positive ninhydrin test) presumably protein, peptones, peptides or alpha-amino acids. It was concluded that the sugars exerted a peptizing or solvent action on the gluten protein. The volumes of the baked gluten balls were not altered significantly, except when lactose or maltose were incorporated in lots of gluten prepared by method (c). l DONNA POLAND MEISKE The crushing forces of the baked gluten balls were significantly decreased when a sugar was added to prepared gluten. In the second experimental procedure 5% increments of D (-) fructose C.P., D (-) glucose C.P., D (+) technical malt- ose, D (+) maltose C.P., beta-lactose 98%, sucrose (cane sugar) or D (+) lactose C.P. were incorporated in a dough untilgluten formation was negligible. The effect of each sugar was fol- lowed by measuring gluten yields and the volumes and crushing forces of baked gluten balls. No gluten was obtained when the following sugars were added at these "critical levels of concentration": fructose, glucose, and sucrose, 55-65%; D (+) maltose C.P., u5%; beta- lactose, uO-h5%; and D (+) technical maltose 30%. The D (+) lactose seemingly did not effect gluten yield, even at the 70% concentration. The technical maltose had the most detrimental effect On gluten formation and character after heat denaturation. Beta-lactose resembled the technical maltose in its effects. The D (+) lactose did not significantly affect gluten yields and the volumes and crushing forces of baked gluten balls. This behavior was related to the insolubility of this sugar. It was concluded that all of the sugars used in this study, except D (+) lactose, either exerted a solvent or Peptizing action on the gluten proteins, or decreased their water absorptive power. La) DONNA POLAND MEISKE As sugar concentration increased, the yields of gluten diminished. The volumes of the gluten balls at the lower levels of a sugar were greater than the controls, and thus indicated that the sugar probably weakened the structure of the baked gluten balls. Crushing forces also were less as the concentrations of sugars were increased. However, at higher levels of concentration, smaller amounts of gluten were obtained and hence the volumes and the crushing forces of the baked gluten balls were less. THE EFFECT OF KIND AND CONCENTRATION OF SUGAR ON GLUTEN FORMATION AND CHARACTER by Donna Poland Meiske A THESIS Submitted to the College of Home Economics of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Foods and Nutrition 1957 ACKNOWLEDGMENTS The author wishes to express her sincere gratitude to Dr; Evelyn Jones for her constant interest and guidance in this study and for her invaluable suggestions in the prepara- tion of this thesis. The writer gratefully extends her sin- cere thanks to Dr. Mary Frang Jones for her great interest and advice in initiating this investigation. She also wishes to thank Dr. William Baten for his assistance in the statistical analyses of the data, Mrs. Sue Walters for her timely assistance during the course of the experiments, and Dr. Margaret Ohlson and Dr. Dena Cederquist for the use of the facilities of the Foods and Nutrition De- partment. She also deeply appreciates the financial support of Michigan State University through an assistantship. Finally, the writer is greatly indebted to her husband, Jay, for his thoughtful encouragement and assistance during the course of the experiments and the preparation of this thesis. ii TABLE OF CONTENTS INTRODUCTION REVIEW OF LITERATURE Historical Method Preparation Protein and Amino Acid Composition of Gluten Gluten Structure Heat Denaturation of Gluten The Effect of Sugar on Baked Products The Effect of Sugar on Gluten EXPERIMENTAL PROCEDURE General Plan Preparation of Gluten Procedure 1 Methods (a) and (b) Method (c) Procedure ll Objective Tests Volume Measurement Crushing Force . . . RESULTS AND DISCUSSION pTocedure I Page Page Drip Loss . . . . . . . . . . . . . . . . . . . 38 Volume . . . . . . . . . . . . . . . . . . . . hl Crushing Forces . . . . . . . . . . . . . . . . ES Procedure 11 . . . . . . . . . . . . . . . . . . . E9 Gluten Yield . . . . . . . . . . . . . . . . . u9 Volume . . . . . . . . . . . . . . . . . . . . 63 Crushing Force . . . . . . . . . . . . . . . . 63 General Discussion of Procedure II . . . . . . 68 SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . 76 LITERATURE CITED . . . . . . . . . . . . . . . . . . 80 iv 4.1. .....I...ill .N J... o Lifaxgfll‘ifili .p :1 .N. ml! . _ E TABLE II. III. IV. VI. VII. VIII. IX. XI. XII. LIST OF TABLES THE EFFECT OF SUGAR ON DOUGH VISCOSITY(2N§ 28) THE EFFECT OF ADDITION OF TWENTY PARTS SUGAR ON GLUTEN, GLIADIN, AND GLUTENIN RECOVERED FROM “OUGHS MADE FROM TWO KINDS OF FLOUR(2Nn 28) THE EFFECTS OF AQUEOUS SUGAR SOLUTION, SUGAR SPIRIT, AND ALCOHOL ON THE SOLUBILITY OF FLOUR PROTEINS (27,.N3). . . . . . . . . . . SUGARS USED IN PROCEDURE I AND PROCEDURE II PROCEDURE I. THE INFLUENCE OF 5% LEVELS OF SUGARS AND METHODS OF INCROPORATING SUGARS ON THE DRIP LOSSES OF GLUTEN . . . . . . ANALYSES OF VARIANCE OF THE EFFECT OF METHODS AND TREATMENTS ON THE DRIP LOSSES OF GLUTEN (PROCEDURE I) . . . . . . . . . . PROCEDURE I. THE INFLUENCE OF 5% LEVELS OF SUGARS AND METHODS OF INCORPORATING SUGARS ON THE VOLUMES OF BAKED GLUTEN BALLS . . . ANALYSES OF VARIANCE OF THE EFFECT OF METHODS AND TREATMENTS ON THE VOLUMES OF BAKED GLUTEN BALLS (PROCEDURE I) . . . . . . . . . . PROCEDURE I. THE INFLUENCE OF 5% LEVELS OF SUGARS AND METHODS OF INCORPORATING SUGARS ON THE CRUSHING FORCES OF BAKED GLUTEN BALLS .ANALYSES OF VARIANCE OF THE EFFECT OF METHODS AND TREATMENTS ON THE CRUSHING FORCES OF BAKED GLUTEN .BALLS ( PROCEDURE 1) .EFFECTS OF INCREASING PERCENTAGES OF D (-) FRUC— 'TOSE ON GLUTEN YIELDS AND VOLUMES AND CRUSHING .FORCES OF BAKED GLUTEN BALLS . . . . . . .EFFECTS OF INCREASING PERCENTAGES OF D (-) GLU- CXDSE ON GLUTEN YIELDS AND VOLUMES AND CRUSHING FTSRCES OF BAKED GLUTEN BALLS . . . . . V PAGE 19 19 21 27 39 DO U2 US DB 50 SI ,4... VIE—II TABLE PAGE XIII. EFFECTS OF INCREASING PERCENTAGES OF SUCROSE ON GLUTEN YIELDS AND VOLUMES AND CRUSHING FORCES OF BAKED GLUTEN BALLS . . . . . . . . . . 52 XJV. EFFECTS OF INCREASING PERCENTAGES OF D (+) MALTOSE C.P. ON GLUTEN YIELDS AND VOLUMES AND CRUSHING FORCES OF BAKED GLUTEN BALLS . . . . . S3 XV. EFFECTS OF INCREASING PERCENTAGES OF D (+) TECHNICAL MALTOSE ON GLUTEN YIELDS AND VOLUMES AND CRUSHING FORCES OF BAKED GLUTEN BALLS . . . Sh )OJI. EFFECTS OF INCREASING PERCENTAGES OF BETA—LAC— TOSE ON GLUTEN YIELDS AND VOLUMES AND CRUSHING FORCES OF BAKED GLUTEN BALLS . . . . . . . . . . SS Nn/II. EFFECTS OF INCREASING PERCENTAGES OF D (+) LACTOSE ON GLUTEN YIELDS AND VOLUMES AND CRUSHING FORCES OF BAKED GLUTEN BALLS . . . . . 56 xVII.I. EFFECTS OF INCREASING PERCENTAGES OF D (+) LACTOSE-IN-SOLUTION ON GLUTEN YIELDS AND VOLUMES AND CRUSHING FORCES OF BAKED GLUTEN YIELDS . . . . . . . . . . . . . . . . . . . . . 57 vi FIGURE 1. 2. 10. LIST OF FIGURES PAGE Loaf volumemeter . . . . . . . . . . . 33 Apparatus used for measuring the volume of one gluten ball . . . . . 3h Apparatus used for measuring the crushing force of gluten balls 36 Effects of increasing percentages of D (-) fructose, D (+) maltose C.P., sucrose, D (-) glucose, and D (+) lactose on gluten yields . Effects of increasing percentages of D (+) maltose C.P., D (+) technical maltose, beta-lactose D (+) lactose, and D (+) lactose-in-solution on gluten yields Probit analyses of the effects of increasing per- centages of D (-) fructose, D (+) maltose C.P., sucrose, D (-) glucose, and D (+) lactose on gluten yields . . . . Probit analyses of the effects of increasing per— centages of D (+) maltose C.P., D (+) technical maltose, beta-lactose, D (+) lactose, and D (+) lactose—in-solution on gluten yields Effects of increasing percentages of D (—) fructose, D (+) maltose C.P., sucrose. D (-) glucose, and D (+) lactose on gluten ball volumes . . . . . . Effects of increasing percentages of D (+) maltose C.P., D (+) technical maltose, beta-lactose, D (+) lactose, and D (+) lactose-in-solution on gluten ball volumes . . . . . . . . . . . . . . . . Probit analyses of the effects of increasing per- centages of D (—) fructose, D (+) maltose C.P., Sucrose, D (—) glucose, and D (+) lactose on gluten ball volumes vii 59 6O 61 62 6h 65 66 FIGURE 11. 12. 13. 1h. 15. PAGE Probit analyses of the effects of increasing percentages of D (+) maltose C.P., D (+) tech- nical maltose, beta-lactose, D (+) lactose, and D (+) lactose-in—solution on gluten ball volumes . . . . . . . . . . . . . . . . . . . . . 67 Effects of increasing percentages of D (-) fructose, D (+) maltose C.P., sucrose, D (—) glucose, and D (+) lactose on the crushing forces of gluten balls . . . . . . . . . . . . . 69 Effects of increasing percentages of D (+) maltose C.P., D (+) technical maltose, beta— lactose, D (+) lactose, and D (+) lactose—in- solution on the crushing forces of gluten balls .. . . . .. . . . .. . . . .. . . . .. 70 Probit analyses of the effects of increasing percentages of D (-) fructose, D (+) maltose C.P., sucrose, D (—) glucose, and D (+) lactose on the crushing forces of gluten balls . . . . . 71 Probit analyses of the effects of increasing percentages of D (+) maltose C.P., D (+) tech- nical maltose, beta-lactose, D (+) lactose and D (+) lactose—in-solution on the crushing forces of gluten balls . . . . . . . . . . . . . . . . . 72 viii INTRODUCTION Wheat gluten is primarily responsible for providing structure in bread and most other baked products. The exclu- siveness of wheat as a bread-making cereal is accounted for .by the special and distinctive characteristics of a protein substance that is intermixed with the starchy endosperm of tJ1€ grain. It is only by virtue of the unique properties of tflnis protein material that carbon dioxide produced during ciough fermentation is retained by the dough in a manner which Ibrovides the familiar porous and spongy structure of bread. 1111s substance, recognized as the "gluten protein" of wheat, cans be readily and conveniently separated from the bulk of time wheat starch. The gluten, itself, is recovered as a co- heIwent, extensible, and rubbery mass, merely by the thorough luuaading (or similar physical manipulation) of flour dough INKhar a stream of water (9). Sugar, too, is an important component of many baked ProdLusts having gluten structure. By increasing sugar to an Optirnum point, there is increased volume and tenderness in these baked products (17,18, 39, LII). An excessive amount of sugar produces a product with a very coarse texture and often a C01lapsed structure (17). In 1911 and again in 1921, Jago and Jago (27,2fl3)re- ported that the physical condition of a flour-water dough l WA. .s. . ’1.“ ..v was noticeably affected by the presence of sucrose. A suffi- cient concentration of sucrose decreased the dough viscosity, which indicated weakening of the gluten structure. They postulated that sucrose had a solvent effect on the flour proteins and that it also affected the water-absorptive power of the flour proteins. Since that time little work has been done to determine the effects of sugars on gluten formation and character. The experiments reported in this paper include studies of the c; effects of various sugars on gluten formation and character, both before and after heat denaturation. Fructose, glucose, lactose, maltose, and sucrose were included in this Study because they commonly occur in baked products. REVIEW OF LITERATURE Historical Beccari, an Italian scientist, is credited with the first separation of gluten and starch from wheat flour in 1728. Beccari's method is as follows, taken from Bailey's translation (2) of Beccari's lecture "Concerning Grain" (7): Flour is obtained from the best wheat, moderately ground, so that bran will not pass through a sieve; from this it follows therefore, that the product is of the cleanest with impurities removed. This is mixed with the purest water and is kneaded. The residue obtained in this oper- ation is accomplished by washing. The water, therefore, carries away all portions that can be dissolved; the other portions it leaves behind intact. Beccari called the glue-like portion "glutinosum" and the other starch-like portion "amylaceum." Since that time, the proteins of flour have been re- peatedly investigated. Accounts of the early studies are primarily of interest historically and have been reviewed by Osborne (NE) and by Bailey (3). The "modern period" of flour protein research is rec- ognized as beginning with the work of Osborne and associates (3). In 1907, Osborne (MB) published a report of studies on flour proteins done over a period of 15 years. He character- ized the proteins of wheat flour on the basis of differing solubility characteristics. The five main fractions based on solubility were as follows: gliadin, a prolamine soluble 3 "l P in. .. II... 0. Ivi 1 n Lil-TM... 5“: .fi h in 70% ethyl alcohol; glutenin, soluble in dilute acid and dilute alkali; a neutral salt-soluble globulin; a water-solu— ble, heat—coagulable albumen; and an ill-defined "proteose". Osborne concluded that the gluten protein constituted more than 80% of the wheat flour protein, and was composed essen- tially of glutenin and gliadin. Method of Preparation The method of extracting gluten from flour by the phys- ical manipulation of a flour dough under water has remained essentially the same as that used by Beccari (7). When gluten was prepared from a flour dough by the usual washing process, Blish (9) reported both the amount and nature of the product were influenced by a number of individ- ual factors. These factors included the character of the flour itself, and the kind of wheat from which it was milled. Flours of higher total protein content usually yielded larger quantities of gluten. It was noted that as the total protein content of the flours increased, the ratio of gluten to non- gluten protein was higher. The author stated that it was frequently difficult to effect proper agglomeration of gluten particles in flours of low protein content, inferior grade, or both. .As a result low or negligible yields of gluten were obtained unless special precautions and very careful handling were used. Dill and Alsberg (20) listed ten factors to consider in extracting gluten from dough: length of the period the dough was allowed to set, length of the period the gluten was allowed to set, temperature, length of wash time, mechan- ical manipulation, nature of the wash water, hydrogen ion concentration of the flour, gluten quality, concentration and kinds of electrolytes in the flour, and gluten quantity. Studies reported by Blish (9) and by Udy (59) indicated that soft water dissolved more gluten protein than hard water. Fisher and Halton suggested that a 0.1% sodium chloride solu- tion be used for washing gluten in cases where sufficient hardness of tap water was lacking. Dill and.Alsberg (20) proposed the use of dilute sodium phosphate solution adjusted to pH 6.8. Fisher and Halton (23) cited other factors to consider in waShing gluten, namely, the temperature of the wash water, length of the rest period between preparation of dough and washing process, and personal peculiarities of the OPerator. Tague (58) stated that a pH range of u.5 to 7.0 Was important in gluten formation. Many mechanical devices have been invented to cut down On the hand labor of washing gluten (3). The electric mixer has been used in fractionation studies (8). Sollars (50) rePorted a method of extracting gluten from wheat flour with dilute acetic acid. He concluded, however, that the acid extraction process required more time than separations made by kneading the dough under water. The use of the acid extraction method was suggested for low~protein flours and flours with damaged gluten. ‘ Due to the presence of substantial quantities of starch, fat, and mineral matter, which cannot be removed by the con- ventional washing process, the term "crude gluten" should be commonly applied to the proteinaceous material recovered by washing a flour dough under water. Blish U9)Statedthat crude gluten as isolated by the washing-out procedure contained an average water content of 65%, while its dry substances con- tained 70-80% protein, S-IS% residual carbohydrates (chiefly starch), 5-10% lipids, and a small quantity of mineral salts. Sullivan (53) reported the composition of gluten to be 85% protein, 8.3% lipid, 6.0% starch, and 0.7% ash (dry weight basis). Protein and Amino Acid Composition of Gluten In 1907, Osborne (NZ) concluded that gluten was com- Posed of two proteins, glutenin and gliadin. Subsequent Studies have supported the view that gluten is composed of several if not many components. Osborne's terminology has been retained for convenience until the identity of the pro- tein components of gluten can be more definitely established. Sandstedt and Blish (D6) and Stockelbach and Bailey (51) rePorted fractionation studies which indicated that gluten was ComPosed of three fractions, namely, gliadin, glutenin, andenI InteI‘mediate they termed mesonin. Sandstedt and Blish (MP) stated that the glutenin fraction was soluble in very concen- trated acetic acid and that gliadin was soluble in 50-70% alcohol or dilute acetic acid. Mesonin was less soluble in neutral (50-70%) alcohol, but was highly soluble in dilute acetic acid. Krejci and Svedberg (29), determined the molecular weight of gliadin by ultracentrifugation and concluded that the protein was not homogeneous with respect to molecular weight. There was probably a mixture of whole and half mole- cules with weights of 3h,500 and 17,500, respectively. Lamm and Polson (32) found that gliadin was heterogeneous,zusshown by differences in diffusion constants of several fractions. However, the most soluble fraction appeared homogeneous. They estimated that the molecular weight of gliadin was 27,500. Burk (l3) determined the molecular weight of gliadin by os- motic pressure measurements in different solvents. The mole- Cular weight values of gliadin varied from h0,000 to 75,000 depending on the solvent used. McCalla and Gralen (35, $5)investigated the molecular Characteristics of gluten in sodium salicylate solution. USing methods of sedimentation and diffusion they found that the molecular weight of the most soluble fraction ranged from 35,000 to hh,000. Schwert et_al, (U8) reported that gliadin Was not an electrophorectically homogeneous protein and con— Sisted of at least two components. These workers determined that the isoelectric point of one fraction was pH 5, while that of the other fraction was pH 7. Fractionation experiments were conducted by McCalla and Rose (37) on gluten in sodium salicylate dispersion. 'The gluten fractions were reprecipitated by varying quantities of magnesium sulphate. Successive fractionations of the pre- cipitated gluten protein contained progressively more amide and less arginine nitrogen. None of the fractions were simi- lar to gluten, but when they were redispersed, combined, and reprecipitated as a whole, a gluten was obtained. The most soluble 10-15% of the gluten protein appeared distinct, but the remainder was probably a single protein complex, which could be progressively fractionated. McCalla and Gralen (35,.fl5)stated that gluten was a protein system which showed progressive and regular changes in solubility. Sullivan (53) reported that the "so-called" glutenin fraction was ill—characterized and non-homogeneous,enuifurther— more that it could not be dispersed in any solvent sufficiently well enough to permit ultracentrifugation, electrophoresis, or other usual physical techniques. Barmore (6) fractionated gluten into components which differed progressively in viscosity and solubility. The dif- ferences in viScosity were interpreted to indicate differences in axial ratio of ellipsoidal molecules. Gliadin appeared to be the most symmetrical and most soluble, yet some of these molecules appeared twice as unsymmetrical as others. Glutenin molecules likewise varied in symmetry and were less symmetri- cal than those of gliadin. Symmetry and solubility in several solvents appeared to be related; the more symmetrical the mol- ecule, the greater the solubility or dispersibility. Barmore believed this evidence further supported the theory that glia— din and glutenin were a part of a complex protein system dif- fering Systematically in physical and chemical properties with no clear distinction between the two. Kuhlmann (30) proposed that gliadin consisted of two fractions, alpha and beta-gliadin. Experiments indicated that glutenin consisted of the longest and most stable micelles. Gliadin consisted of shorter micelles which were less stably built and more flocculent than those of glutenin. The beta- gliadin fraction was similar in swelling, peptization, and length of micelle, to glutenin. Blish (9) summarized the evidence supporting the in- dividual protein components and homogeneity of gluten protein as follows: 1. Gluten protein is definitely inhomogeneous and probably consists of several, if not many compo- nents, instead of two as postulated by Osborne (U2). 2. Non-homogeneity appears to increase with a decrease in solubility of the various protein fractions. 3. Evidence of non-homogeneity may however be due, in considerable measure, to aggregation, and to compo- nent interaction with "complex formation," rather than to the actual existence of numerous individual components. 10 U. The solubility characteristics of gluten present unique difficulties and complexities when attempts are made to apply and interpret modern physical methods for studying protein individuality and molecular properties. 5. Convincing solution of the problem of gluten structural composition and homogeneity apparently must await discovery and application of appropriate solvents, or of new methods and criteria, or a combination of these developments. The amino acid composition Of gluten prepared from seventeen different flours was determined by Pence and co- workers (U3). The amino acids present in gluten (as percent of protein with a theoretical average nitrogen content of 17.5%) were as follows: alanine 2.2%, arginine U.7%, aspartic acid 3.7%, cystine plus cysteine 1.9%, glutamic acid 35.5%, glycine 3.5%, histidine 2.3 %, isoleucine U.6%, leucine 7.6%, lysine 1.8%, methionine 1.9%, phenylalanine 5.U%, proline 12.7%, serine U.7%, threonine 2.6%, tryptophane 1.1%, tyrosine 3.1%, and valine U.7%. Gluten Structure When water is mixed with wheat flour in proper propor- tions, gluten is formed. Osborne (U2) suggested that glutenin formed the nucleus to which the gliadin adhered and this bound the gluten protein in one coherent elastic mass. Bungenberg de Jong (ll) theorized that gluten was not just a physical mixture of gliadin and glutenin, but that its existence was dependent upon an interaction between these two components. This interaction was a result of the opposition mini ..I.. iii... ii... ‘ Zr, 4 1;“. a h law. ll of charges on the two components in the complex. In the region of the complex formation, gliadin was always the posi- tive component, and glutenin the negative component. The glutenin-gliadin ratio, therefore, was thought to influence, to some extent, the physical properties of the gluten. Par- ticle size, and presence of other proteins (albumins, globu- lins, and peptones) were also thought to alter the amount of gluten formed. Kuhlmann (30) suggested that gluten be considered as a high polymer representing a complex of proteins, forming micelles of various lengths. Sullivan t al. (5U) proposed that gluten strands are coiled fibrils of proteins with main or side chains containing disulfide bonds. Laitinen and Sullivan (31), in studying the oxidation-reduction systems in flour, found the presence of possible sulfhydryl linkages in gluten. Cunningham (l6) postulated that gluten might be formed by four types of bonding: peptide bonds, hydrogen bonds, salt linkages, and disulfide bonds. The basic pattern of gluten structure was probably due to polypeptide chains. The rela- tively high amount of the amino acid proline was thought to fio< the configuration of the polypeptide chains in one par- ticnilar way. Hydrogen bonds, salt linkages, and disulfide .bormis were thought to be interchain linkages. Hydrogen bonds werwa easily ruptured and easily reformed. Salt linkages were ShOMHI to be present by the ready solubility of gluten in 12 dilute acid or alkali. The disulfide bonds probably had their origin in cysteine, which was found to be relatively abundant in gluten. It has been emphasized that gluten is a colloidal system (12, l6,U5, 56,57). Swanson (56,5?7)suggested a three—dimen- sional gluten network in dough. When dough was formed from a flour and water mixture it was probable that the protein par- ticles which formed gluten united into filaments or strands. In a well-mixed dough these strands had a three-dimensional network which permeated the whole dough and thus formed a Continuous phase system. The amount of protein determined the density of the network and the quality determined the behavior. The starch granules were enmeshed in this network. The layers of water which were adsorbed on the protein par- ticles and on the starch also formed a continuous phase or System. Baker_et‘_1. (U) studied the distribution of water in dOugh and proposed that the hydrated gluten in a dough was 1argely fluid in its action. The gluten had elastic proper- ties due to its cohesions and thus rendered the dough slightly elastic by bonds between gluten micelles dispersed throughout the dough. Dough properties were modified, however, by an approximately equal volume of suspended starch which added puttY-like properties to the dough. Dempster gt 1. (l9) studying the relaxation of internal StreSses in non-fermenting bromated and unbromated doughs, 13 supported the three-dimensional network theory. Since dough was partially elastic, it was postulated that it contained flexible, long-chain molecules (presumably protein) with some cross-links between neighboring molecules, creating a three— dimensional network. The cross-links were probably points of strong intermolecular or secondary valence forces between polar groups of adjacent molecules, rather than primary co- valent bonds. Sections of the long molecules between the cross-links were thought to assume randomly kinked or crumpled configurations. The structure was probably dynamic and the shape and degree of kinking in the individual molecular seg- ments changed readily. It was further stated in this report (19), that in a rested dough, the length of the molecular segments between the cross-links of the postulated network structure were ran- domly oriented with respect to each other. A certain minimum number of polar groups were considered to be involved hilabile intermolecular cross-links which changed in position but re— mained essentially the same in number. When the rested dough was shaped by comparatively mild manipulations involved in rounding and rolling, the mean length of the molecular seg- ments was increased by mechanical unkinking. Previously non- bonded polar groups in adjacent molecules were also brought into adjacent position by this manipulation. Intermolecular forces between these groups established additional cross- linkages in the network. Internal stresses were thus set up 1U in the dough by working and a considerable force was required to stretch the dough. Upon standing, the dough again reached equilibrium between the numbers of bonds breaking and reform- ing, internal stresses relaxed, and less force was needed to stretch the dough. Udy (59) reported that glutens became more resistant to stretching after resting as contrasted to doughs which mellow and soften as a result of relaxation of their internal stresses during resting. It was suggested that new associa- tions between protein molecules accounted for the increase in strength during the resting or mechanical working of the "purified gluten". Heat Denaturation of Gluten Neurath et.al. (U0) defined denaturation as, "any non- proteolytic modification of the unique structure of a native protein giving rise to definite changes in chemical, physical or biological properties." Limited work has been done on the heat denaturation of gluten. .Alsberg and Griffing (l) heated disks of gluten in water in a water bath. Ability to swell in dilute acethsacid was used to measure the extent of denaturation. They con- cluded that heating gluten alters its power to swell. The swelling diminished as the temperature increased from 50°CL to 80°C. Denaturation seemed to take place over the whole range between 50°C. to 80°C., but seemed to be most rapid between 60°C. to 65°C. 15 Pence _£._i: (UU) studied the effect of time, tempera- ture, moisture content, pH, and salt concentration on the denaturation of gluten by heat. The denaturation of wet-gum gluten was found to have an activation energy of approximately 35,000 calories per mole when measured by a baking test method, and UU,000 calories per mole when measured by a solubility method. The rates of denaturation at both 80°C. and 90°C. were negligible at low moisture contents but rose rapidly to an optimum point between 35 to U0 5% moisture. At higher moisture levels the rates declined slightly toward intermedi— ate levels. Denaturation was slow at pH U, but became more rapid at higher pH levels. The relations among pH, tempera- ture, and rate of denaturation were found to be quite complex. At low pH values, damage to the baking properties of gluten occurred which was not due to heat. Variation in salt con- centrations had no effect on the rate of denaturation. Pence at _L. (UU) and Cook (1U) found that the dena- turation of the gliadin fraction was much slower than that of the whole gluten complex and was characterized by a defi- nite induction period. The studies of Cook (1U) indicated that when gluten proteins were subjected to elevated tempera- tures, the glutenin fraction was first affected, next the gliadin fractions of low solubility, and finally under severe conditions all of the gliadin was denatured. .‘u . ‘u «I OTIIHMII . Jim b ‘. mll F. 16 The Effect of Sugar on Baked Products It has been noted that the addition of too great a quantity of sugar in baked products produced undesirable re- sults; fallen structure and decreased volume. Experiments varying the proportion of sugar (sucrose) in cake led to the conclusion that increasing sugar up to a certain point im— proves texture, tenderness, and volume. It was not possible to increase the quantity much above an optimum point without causing the cake to fall (10,15, f7,39,lrl,52). de Goumois and Hanning (18) reported that there were increases in volume and compressibility of yellow cakes when the total sugar content of the cake formula was increased 15 or 30% by the additions of sucrose, glucose, alpha-lactose or beta-lactose. The increase in volume and compressibility were always greater at the 30% level of any of the sugars. The cakes which had additions of beta-lactose and sucrose had the largest volumes, and those with beta-lactose were more com— pressible throughout the storage period of five days. Sandstedt and Blish (U7) reported the effects on loaf properties of bread produced by variations of added sucrose over a range of 2.5 to 5.5 g. per 100 g. of flour. Effects were unimportant when shortening was ommitted. When shorten- ing was included in the formula and the sugar was increased from 2.5 to 5.5%, a significant volume increase was noted. Barham and Johnson (5) studied the influence of sucrose, glucose, fructose, and invert sugar on bread and dough 17 properties. They found that bread made from a dough contain- ing 2 to U% sugar had minimum crumb firmness. In samples containing more than U% sugar, the crumb firmness (measured twenty-four hours after baking) increased to a greater extent than could be accounted for by volume differences. They pro- posed that sugar might have served as a bonding force and hence created a firmer less resilient crumb. Larmour and Brockington (33) reported the effects of variation in formulas of bread made from three flours. They observed that with one flour that loaf volume increased as the sugar content of the formula was raised. This result was not noted in the volumes of bread made from the other two flours. Micka and Child (38) stated that there was a decrease in adsorption of a dough as the sucrose content of a bread formula was increased. They also noted that a dough made with flour, water, and sugar was slacker directly after mixing than a dough made with flour and water which became still slacker- on standing. The Effect of Sugar on Gluten Limited work has been done on the effect of sugars on gluten formation and Character. Jago and Jago (27,z%3)reported a study on the effect of adding sucrose to a flour and water dough. They noted that when sugar was added to the dough, the dough became softer and stickier than dough to which no l8 sugar had been added. If the sugar-dough was to attain the same viscosity as the flour-water dough, water had to be re- duced. The results of this study are summarized in Table I. Iago and Jago (27,z%3)further studied doughs made from two different kinds of flour, with and without the addition of 20 parts of sugar. Wet gluten was determined after wash— ing the flour dough. Dry gluten was determined after the wet gluten was air dried and finely ground. The protein of the true gluten was estimated by nitrogen analysis (Kjeldahl meth- od) on the dry gluten. Gliadin was found by dissolving wet gluten with 70% alcohol, filtering, and estimating the protein of the filtrate by nitrogen analysis. Glutenin was found by subtracting gliadin from true gluten. In all cases the sugar caused a diminution in the quantity of gluten recovered, ex- cept in\the case of the dry gluten of one flour. The results of this study are summarized in Table II. When extracted with alcohol, much more gluten was dis— solved by sugar-spirit (20% sucrose in 70% alcohol) than by the 70% alcohol alone. The experimenters concluded that sugar had a marked solvent action on the wet gluten. The total protein of the two flours was directly estimated by nitrogen analysis. The proteins soluble in water were determined by directly treating the flour, filtering, and estimating the protein of the filtrate by nitrogen analysis. The proteins soluble in 70% alcohol were estimated by direct treatment of the flour, and estimating the protein of the filtrate by 19 TABLE I (27, 28) THE EFFECT OF SUGAR ON DOUGH VISCOSITY Weight in Grams Viscosimeter Time I. Flour 100, water 50 106 seconds 11. Flour 100, sugar 20, water 50 9 seconds 111. Flour 100, sugar 20, water U8 16 seconds IV. Flour 100, sugar 20, water U6 28 seconds V. Flour 100, sugar 20, water UU 50 seconds VI. Flour 100, sugar 20, water U2 6 seconds VII. Flour 100, sugar 20, water U0 86 seconds VIII. Flour 100, sugar 20, water 38 36U seconds Sucrose was the sugar used in this experiment. TABLE II (27, 28) THE EFFECT OF ADDITION OF TWENTY PARTS SUGAR ON GLUTEN, GLIADIN, AND GLUTENIN RECOVERED FROM DOUGHS MADE FROM TWO KINDS OF FLOUR Constituents Flour A Flour B . Sugar- . Sugar— OrdInary dough Ordinary dough 9- 9- 9- g. Gluten, wet 37.2 35.9 26.7 23.9 Gluten, dry 11.3 11.7 8.2 7.7 Gluten, true 10.U 10.0 7.5 7.2 Gliadin, ex gluten 3.6 7.2 3.0 5.6 Glutenin 6.8 2.8 U.5 1.6 Sucrose was the sugar used in this experiment. 20 nitrogen analysis. The proteins similarly dissolved by the sugar-spirit were also determined. The results of this study are summarized in Table III. Jago and Jago (27,2fi3)assumed that water and sugar— water, respectively, did not dissolve the same proteins as did the alcohol and sugar-spirit, but that there was probably some overlapping. It was noticed in every case that an in- creased solvent power was exerted when sugar was present. In all cases the sugar-spirit dissolved considerably more protein than 70% alcohol alone. Sugar diminished rathertimniincreased the absorptive power of the flour proteins. It was thought that small quantities of sugar exerted a solvent action on the gluten and effected sufficient softening which increased the gas—retaining power of doughs and thus indirectly increased the strength of the flour. McAuley (3U) studied the effect of sucrose on sodium salicylate dispersions of gluten._ It was found that the sugar decreased the intrinsic viscosity of the gluten dispersion. This decrease was thought to indicate a decrease in the par- ticle size or axial ratio of gluten. This assumption was based on the theory that gluten molecules were coiled chains which were free to react with other molecules. Changes in attractions within the molecule or between molecules would be reflected by change in viscosity. It was therefore as- sumed that sucrose brought about these changes. 21 TABLE III (27, 28) THE EFFECTS OF AQUEOUS SUGAR SOLUTION, SUGAR—SPIRIT, AND ALCOHOL ON THE SOLUBILITY OF FLOUR PROTEINS Constituents Flour A Flour B % % % % Total proteins 11.6 11.6 9.9 9.9 Proteins soluble in water 1.0 0.5 Proteins soluble in sugar-spirit 1.5 2.5 Gliadin and glutenin 10.6 10.1 9.U 7.U Soluble in alcohol, gliadin 6.U U.6 Soluble in sugar—spirit, gliadin 7.5 5.7 Insoluble glutenin U.2 2.6 U.8 1.7 Sucrose was the sugar used in this experiment. 22 Frang (2U) studied the effects of sugars on heat de- naturation and coagulation of gluten. The effect of glucose or sucrose on gluten was determined by measuring the change in sulfhydryl groups and the soluble nitrogen of the filtrate from lactic acid dispersions of gluten during heat and pH Change. Glucose, fructose, maltose, lactose, invert sugar, and sucrose were incorporated in gluten and the volumes of the baked gluten balls were determined. Soluble nitrogen was determined on part of the latter series. The results of the study indicated that the presence of either glucose or sucrose decreased slightly the amount of oxidizable sulfhydryl groups, and increased the soluble nitrogen in the filtrate. it was concluded that these two sugars interfered with the denaturation process and brought about a peptization of the coagulum. From the results of the experiments on baked gluten balls Frang (2U) noted that an increase in per cent soluble nitrogen might be caused by sugars other than glucose or sucrose. Gluten was prepared from two kinds of flour and the following sugars were added in amounts equivalent to 5 or 10% of the flour used to prepare the gluten: sucrose, glucose, lactose, maltose, fructose, and simulated invert sugar. There was usually an increased solubilization of ni- trogen at the higher concentration. Separate determinations of nitrogen in the crust and crumb of baked gluten balls showed that there was a greater concentration of soluble 23 nitrogen in the crust than in the crumb of the gluten ball. From the volume of the baked gluten balls measured by seed displacement, it was concluded that at the 5% level, fructose, invert sugar, and maltose had the greatest beneficial effect on volume; and at the 10% level, they had the least detrimen- tal effect. Lactose always had the most detrimental effect at either level. Hlynka and Bass (26) studied the reaction of dough and gluten with 5% glucose. It was found that a storage period was necessary to bring about the glucose-protein interaction. It was also shown that the reducing value of gluten was un- changed by washing the gluten to remove the added reacted glucose. This evidence was believed to support the hypothesis that reducing carbohydrates in dough and gluten act as cross- linking agents between protein chains to form a three-dimen- sional network. Similar studies were reported by Hlynka and Anderson (25) on the glucose-protein interaction on material prepared from high, medium, and low-protein flours of five different varieties of wheat. High-protein flours gave the lowest ini- tial reducing values and also the greatest increase in reduc— ing values after a storage of six months. When glucose was added and intimately mixed with water, and moisture removed to the original level, reducing values increased several fold. The same general trend was obtained from analogous experiments with gluten prepared from high, medium, and low-protein flours. 21+ However, gluten from low-protein flour showed a greater re— activity toward the added glucose than gluten from high- protein flour. EXPERIMENTAL PROCEDURE General Plan Two experimental procedures were employed in this study. An all purpose flour (Gold Medal All—Purpose Flour) was used throughout the study. In the first procedure a 5% level, based on the water weight, of either D (-) fructose, D (-) glucose, D (+) techni- cal maltose, beta-lactose, or sucrose were added: (a) to a flour-water dough in the preparation of gluten, (b) to gluten prepared from the preceding method, and (c) to prepared gluten made from only a flour—water dough. Weights of the gluten lots (plus the weight of the sugar, if sugar were added) were re- corded before and after mixing. The amount of drip loss of the gluten lots as affected by the presence or absence of each sugar was determined in this way. The gluten obtained from these three methods was baked in the form of balls. The ex- tent to which each sugar affected the gluten structure was determined by comparing the volumes and crushing forces of baked gluten balls. In the second experimental procedure, increasing percent— ages of each sugar (based on the flour weight) were added to a flour-water dough until gluten formation was negligible. The sugars used were : D (-) fructose, D (-) glucose, D (+) technical maltose, D (+) maltose C.P., beta-lactose, D (+) 25 ’in.-.lp¢1fllq 51.. A 26 lactose, or sucrose. The yield of gluten obtained after each increasing addition of each sugar indicated the amount of gluten formation. The amount of gluten obtained for each in- creasing level, was baked in the form of a ball. Volume and crushing force of these balls were Compared to those with no sugar added. In this way the extent to which each sugar affected the gluten structure was tested. Preparation of Gluten Procedure I Methods (a) and (b). Wet gum gluten was prepared from 355 g. of flour, 288 ml. tap water, and 1U.U g. of sugar (5% of the water weight). The sugars used were either D (-)fruc- tose, D (-) glucose, D (+) technical maltose, beta-lactose, or sucrose (Table IV). The study consisted of four replica— tions of each sugar and the control. The flour, sugar, and water were mixed 5 minutes in a Kitchen Aid Mixer (Model K 52A). The dough was scraped down at the end of the second and fourth minutes. .At the end of the mixing period the 00H 000 - - 0.0 m - - H.0 0.0 - - 00 000 000 - - 0.H : - - H.0 3.0 - - 00 000 00: N00 000 0.0 0H 0 a 0.0 m.H 0.H 0 0 00 000 0000 0:0 000 0.00 00 0H 0H 0.0 0.0 0.H 0 m 0: 0000 H0Hm NSHH 0000 0.00 00 00 0: 0.0 0.0 :.0 H.0 0: 000m 000m osmH 000m 0.H0 00 00 00 0.0 0.0 0.0 0 0 00 0000 0000 000H 0000 0.00 00 00 00 0.0H 0.0 0.0 0 0 00 0Hm0 00:0 00:0 0000 0.H0 00 00 00 0.0H 0.00 0.0 0.00 0m 0000 0000 0000 H000 0.00 00 00 00 0.0H 0.0H :.0H 0.0H om 0000 S000 00H0 000: 0.00 00 00 00 0.0H 0.0H 0.0H 0.0H 0H 0000 N00: :H00 0000 0.00 00 00 00 0.0H 0.0H m.0H 0.0H 0H 00:0 :Hmm 0000 0:00 0.00 0HH 00 00 0IOH :.0H 0.0H 0 0H 0 000: 000: H000 0000 0.00 00 00 00 H.HH m.HH m.Hc 0 0H 0 and: m m H can: m m H and: m N H owOpUdcm meHpmoHHaom wcoHHmoHHQom mcoHHmoHHQmm Haw Q H.mv HHmn doHsHm oco £0300 H.HEV HHmQ CmHSHm H.mv doHde Ho UHUH> mHA QZ< mQHmH> ZMHDHO ZO mmOHODmm ATV Q 00 me 00 000 - - 0.0 - - H H.0 - - H.0 00 00: 000 :00 000 0.0 H 0 m 0.0 H.0 0.0 0.0 00 0H0 0:0 0H0 H00 0.0 0H 0H m 0.H 0.0 0.H :.0 00 00HH :000 00: H00 0.HH 0H 0H : H.m 0.0 0.0 0.0 0: 000H m00H 000H 000 0.Hm 00 00 0H :.0 0.0 0.: 0.0 0: 0m:H 000H 000H 0HOH 0.0: 00 0: 00 0.0 0.0 0.0 0.0 00 0000 00:0 0:00 :000 0.00 00 00 00 0.0 0.0 H.0 0.0 00 0Hmm 000H 000H HHm0 0.00 00 00 00 :.0 0.0 0.0 0.0 00 H0H0 0:H: 00Hm 0000 0.00 00 00 00 0.0H 0.0H 0.0H H.0H 0m 0000 0000 00:0 0H0m 0.H0 00 00 00 0.0H 0.HH 0.0H :.0H 0H 0000 0:00 00H: 0::0 0.00 00 00 00 H.HH 0.HH H.HH 0.HH 0H 0:H0 0000 0000 0000 0.00 00 00 00H H.0H 0.0H 0.0H 0.0H 0 0:00 0000 0000 0000 0.00 00 00 00 0.HH :.HH 0.0H 0.0H 0 0002 0 m H 0002 0 m H 0002 0 m H amoosHo meHbmoHHd0m mcoHpmoHHd0m meHpmoHHd0m HIM Q H.mv HHmn ampsHm 0co c0500 H.HEV HHmn :003Hm H.mv C0psHm mo 0H0H> wHA QZ< mQHmH> ZMHDHO ZO MmOODHO HIV Q 00 wm0 mH4 02¢ mQHmH> ZMHDHO ZO MmOmUDm mo mm0 N 00 000000 00000 00 pedofid 000 00.0ESH0> mH4 QZ< mQHmH> ZMHDHO ZO .m.u mmOHH¢Z 0+0 Q 00 mmodHZmommm OszHX MHm H+M Q 00 00000: 00000 00 pesoE< 000 00 0&0Ho> mH4 QZ< mQHmH> Q 00 mmO¢Hzmummm Osz¢mmUZH mo mbummmm ZMHDHO ZO MmOHHX mHm 00 000000 00000 00 000084 000 00 0E:H0> mH4.QZ¢ wQHmH> zmHDHO ZO MmOHudqndem mo mm0¢Hzmommm OZHmX MHm HH00 0000H0 H.00 0000H0 08 0H0H> N HH>X mqmdfi mHH¢m ZMHDHO Qm2¢m LO wmomOm OZHImDmO QZ¢ mMZDHO> 02¢ mQHmH> ZMHDHO ZO MmOHO¢H H+V Q 00 mMOdemommm 02Hm0 65 7o % Sugar Sig. 5. Effects of increasing percentages of D (+) maltose C.P., D (+) technical maltose, beta-lactose, D (+) lactose, and D (+) lactose-in-solution, on gluten yields. Each point is the average of three replica- tions. 61 .020000000000 000:0 mo 0H00> Hmpog 0:0 :0 0000p 000 0000000 .000002 C0030m co 000000H “+0 Q 000 .mmoosfim 0.0 Q .0000030 ..m.u 0000005 A+V Q .00000000 Any Q 00 00m0020000a @0000000c0 00 0000000 020 00 m0mhfima< 000000 b .mwm cmmsm N 00 00 00 00 00 0: 0: 00 00 00 00 0H 0H 0 H ..ll.g LU» --J 0 4H .AL _ 4‘ 4 Hillad- H H r 1H 1 .JN 40 .0 LH -0 ..0 00000000 O [0. n 0moosHo “IV Q A» 0000.004 A: Q 0 1 .m.u 0000H02.A+; 0H 0 1 I 00000500 Any Q I w 00000 000000 62 .cofipsQom 100-000000Q A+v Q 000020 0020000000000 00020 00 0Q0HA 00000 020 :0 00000 000 000000m .000000 C003Qm co cowusQomucHn000000~ A+V Q 000 .000000H “+0 Q .000000Qn0000 .0000Q0E Q00002000 A+v Q ..m.u 0000Q0E A+V Q 00 00000200000 0000000020 00 0000000 020 00 m0m>H000 00000m .0 .000 pmmsm N ON. mo 00 mm om m: 0.: mm. Om mm. ON ma 0.. m 0 H 4| m 4 0...... w r; - 8 A _ . _ r- L H r . r. 00 I .40 I 4.: .. n 0 I J b I 000000Qn000m 0 0 00000000100a0000000 0+0 Q 6 J 0000000 A+V Q 0 I 0000Q02 Q00022000 A+v Q B u w .m.u 0000sz A+v Q U 0Qm0m 000000 63 Volume The volumes of gluten balls are tabulated in the same tables discussed under gluten yield. It was noted that after initial concentrations of each sugar had been added, the gluten yields were smaller than the yields of gluten which had had no sugar addition, yet the volumes of these same gluten balls were usually greater than the volumes of the controls. .Aver- age volumes for each level of addition of the various sugars are shown in Figs. 8 and 9. However, as the concentration of the sugars became higher, the volumes of the gluten balls ob- tained were smaller. .These decreased volumes were attributed to smaller gluten yields at the higher concentrations of each sugar. Probit analysis (22) of the gluten yields are shown in Figs. 10 and ll. Glucose, fructose, and sucrose exerted similar effects on gluten ball volume. The volumes of gluten balls made with D (+) technical maltose were usually smaller than the volumes of the gluten balls made from the same con- centration of all of the other sugars used in this study. The effects exerted by beta—lactose and D (+) lactose-in-solu- tion were similar. The D (+) lactose did not affect the ‘volumes of gluten balls to any extent. Crushing Force The crushing forces of the gluten balls of the various sugars are presented in the same tables discussed in gluten yield. In general, as the level of concentration of a sugar 6b. Volume (m1.) I D (-) Fructose O D (+) Maltose C.P. 110 o D (+) Lactose V A D (-) Glucose ' 100 L O Sucrose q 90 '— . - O _ 'K’ 0, o o /\ 80 o’,/’.m'p.\ R /\/ (V/o 70‘ .v/ \ ‘Vs ‘ . — - I 60 . _ SO - A b no l- \ .. 30 *- T ' A 20 L- 1 10 - ‘ . - O I L l l l 1 LL bi 1_ 1w“... 5 10 15 20 25 3O 35 LiO I45 50 SS 60 65 7O % Sugar Fig. 8. Effects of increasing percentages of D (-) fructose, D (+) maltose C.P., sucrose, D (-) glucose, and D (+) lactose on gluten ball volumes. Each point is the average of three replications. l_ I L J 65 Maltose C.P. Technical Maltose Lactose Lactose—in-Solution" Beta—Lactose ‘ \l / filOKDaCJ DUUU :3++-+ J-—-— - 4—- - 10 15 20 25 CM) 35 MO MS 50 SS 60 65 7O % Sugar Effects of increasing percentages of D (+) maltose C.P., D (+) technical maltose, beta-lactose, D (+) lactose and D (+) lactose-in-solution on gluten ball volumes. Each point is the average of three replications, except D (+) lactose-in-solution. 66 .000000000000 00000 00 0EsHO> 00000 0:0 00 00000 000 0000000 .008500> 0000 000500 00 0000000 A+V Q 000 .000020m Any Q .0000020 ..0.U 0000008 0+0 Q .00000500 Any Q 00 00m00000000 @000000000 00 0000000 0:0 00 00050000 000000 .00 .000 00msm R 00 mo 00 mm om mu0 o: 00 00 mm om 00 00 m ., r o <.Aflflw a _ A at _ q . 0+ q 0 A w 4 0 T i m i 4» I m T O Iii—4 1 .L m I H I. 0 0/4 0 0000006 0 r 0000500 A; Q d .4 N. 0000000 Tl Q O .0.0 0000002 A+v Q 0U I 00000500 Anv Q I I w 00000 000000 67 .00003000100-0000000 0+0 Q 0000x0 .000000000000 00000 00 0E30o> 00000 0:0 00 00000 000 0000000 .00E:0o> 0000 000200 co 0000:000uc0n0000000 0+0 Q 000 .0000000 0+0 Q .0000000u0000 .0000005 000000000 0+0 Q ..0.U 0000008 0+0 Q 00 00m00000000 0000000000 00 0000000 0:0 00 000>00C0 000000 .00 .000 00m3m R 00 00 00 .mm om m: o: 00 Om mm om 00 00 m _ _ 0 0 0| I». 0» n d. _ i0 14 0 _ o / ,. - : JOIIIJVJII n I ///AF [01/ n” .112 V“ 0| [/0 /%/r4 1 m D /O , if 00%;. I 011/: w. 1 0 0000000n000m O 9/0 T COHpSHOmacwlmmOpUmup A+v Q G L N. 0000000 0+0 Q 0U 0000002 00000000H 0+0 Q 2 h .0.0 000000: 0+0 Q Q 0 n m 00000 000000 _ 68 increased the amount of force needed to crush a gluten ball became less (except in the case of D (+) lactose). Part of the decrease in the amount of force needed to crush gluten balls might have been due to the effect of the sugar used actually weakening gluten structure; however, at the higher levels, less gluten was obtained and hence, less force was needed to crush the gluten balls. Figs. 12 and 13 illustrate the decreases in crushing forces as sugar concentrations were increased. Probit analyses (22) of the crushing forces are shown in Figs. lb, and 15. Gluten balls which had had additions of glucose, fructose and sucrose were similar in crushing forces. The gluten balls, to which D (+) technical maltose had been added, had lower crushing forces at lower levels of concentration than gluten balls to which comparable concen- trations of the other sugars had been added. Tlmaglutenlxalls made from beta—lactose and D (+) lactose—in-solution had similar crushing forces. The D (+) lactose seemed to have no significant effect on the crushing forces of gluten balls when added at any level of concentration. General Discussion of Procedure 11 Technical maltose, which contained lO-lS% dextrins, seemed to have the most detrimental effect on gluten forma— tion, and the volumes and crushing forces of baked gluten balls. The dextrin content of this sugar is thought to limit gluten formation to some extent as the C.P. maltose did not 69 Crushing force (9.) 5000 MSOO hOOO 3500 3000 2500 2000 1500 1000 500 C D (—) Fructose - O D (+) Maltose C.P. ' C) D (+) Lactose _ a A. L)(-) Glucose ‘ 0 Sucrose 4 A\. i o 0 /O“‘“fl- -~- \ /// 4\\\E///d/// J 4 1 I A \ '1 \ 0 ‘l A 01 L .“_.\ O 5 10 15 2O 25 30 35 no A5 50 55 60 65 70 % Sugar Fig. 12. Effects of increasing percentages of D (-) fructose, D (+) maltose C.P., sucrose, D (-) glucose, and D (+) lactose on the crushing forces of gluten balls. Each point is the average of three replications. ’L "L‘ .V-filfi'OrH"P‘? .‘ 70 (133521213 ) 0 D (+) Maltose C.P. ‘ S D (+) Technical Maltose o £)(+) Lactose 5000 O D (+) Lactose-in-Solution W 0 Beta—Lactose MSOO d uOOO _ e J W /\ =- " 3000 0 2500 ’/// J 2000 0 1500 2 1000 4 500 ';: 1 J I J 5 10 15 20 25 30 35 no u EX) 55 60 65 7O % Sugar Fig. 13. Effects of increasing percentages of D (+) maltose C.P., D (+) technical maltose, beta-lactose, D (+) lactose, and D (+) lactose-in-solution on the crush- ing forces of gluten balls. Each point is the average of three replications, except D (+) lactose- in-solution. 71 i fl“11.1....” . . . ".... .. i. 1 . .x . ... 7 1| ./ ... . .\ . . . 0 .. pl . . . i: . . . . . . . .0 . . _. .13! ... 10.... .00.-..3030t-fii ..m. m” H“ .000000000000 00000 00 00000 00000000 00000 000 00 00000 000 0000000 .00000 000000 00 000000 00000500 000 :0 0000000 0+0 Q 000 .0000000 0-0 Q .0000050 ..0.u 0000008 0+0 Q 000000200 0-0 Q 00 00000000000 ©000000000 0000000 000 00 00030000 000000 .00 .000 00msm R 00. 00 00 mm om m: o: 00 00 mm om 00 S m o 4 . a 0 0| _ 0 _ 0 _ 0 _ J ET / 10 0 - u N T. 41/ . I m l/ D, . . /D/ f. O: 1 AV/ L o 0 O O Oflr Q Iva/B/ T 10-1/V- /, , Q a I m 0.! O /4 .... O O/fi. T ./< L 0 o 000003m . 0000300 A; Q N I .0. 008.000 0+0 0 o .. .00 003002 0+0 0 o :0 00000500 0-0 Q I L 00000 000000 72 .00H05Q00-00-000000Q A+V Q 0000x0 .000Q000QQQ00 000:0 Q0 00000Q mcwc0000 Q0000 0:0 00 00000 000 mpwnoum .0QQ00 0005Qm Q0 00000Q mcwzmspu 0:0 00 00Q05Q00ncwn000000Q A+V Q 000000Q A+v Q .000000QI000Q .0000Q0E Q00QCQ000 A+V Q ..m.u .0000Q0E n+v Q Q0 00m0000000a mcH00000cQ Q0 0000QQO 0:0 Q0 000>Q0C0 0QQ00m .mQ .mHm 0mmsw R ow 00 00 mm om m: 0: mm on m0 om m0 00 m . 0 d _ + O 7 AM .1 I.N 0- u 0 J/«Q/ Afi 1 m .r I o r 0000004-000m O I N :0Q05Q0mucfin0000004 A: Q 0 0000004 A+v Q Au r 000yQ02 Q00QCQ00H A+V Q Z .m.0 .0000002 Q+v 0 0 I m 0Q000 000000 73 effect gluten formation, and the volumes and crushing forces of the gluten balls as much as did the technical maltose. The C.P. maltose, however, had a more detrimental effect on gluten yields and the volumes and crushing forces of baked gluten balls than did glucose, fructose, sucrose, or D (+) lactose. The D (+) lactose did not significantly affect the gluten yields, and the volumes and tenderness of baked gluten balls. The beta-lactose and D (+) lactose-in-solution exerted similar effects on gluten yields, and the volumes and crushing forces of baked gluten balls. The data suggest that the effects of sugars on gluten formation may be related to the solubility of sugars. The D (+) lactose seemed to be insoluble in the water present in the dough and exerted no significant effects on gluten yields and on the volumes and crushing forces of the gluten balls. Whittier (00) stated that beta-lactose is more soluble than alpha-lactose. He also reported that a lactose which had a + 55.5 rotation was an equilibrium mixture of the alpha and beta forms, and that the alpha-form may be converted to the beta-form if crystalization takes place above 93°C. The D (+) .lactose used in this study had an optical rotation of -+ 52.2-52.5° and, therefore, probably consisted of a near ecuiilibrium mixture of alpha and beta-lactose. Thus when the I) (+) lactose was mixed with water and heated to form a soltrtion, the alpha-form was probably converted to the beta- fornh The similarity of the effects of beta-lactose and :3 oi. . ‘L. . Mr! 7h the D (+) lactose-in-solution may be explained in this man- ner. Jago and Jago (27,.fi3)reported that as the concentra- tion of sucrose in a sugar-flour—water dough was increased, the dough viscostiy decreased. They further studied the effects of sucrose in water solution or in alcohol solution on gluten protein. They concluded that the sucrose might have had a solvent effect on the flour proteins and that it also affected the water absorptive power of the flour pro- teins. McAuley (3h) found that sucrose decreased the viscos- ity of sodium salicylate dispersions of gluten and concluded that this decreased viscosity was due to the fact that the particle size or the axial ratio of the gluten molecules was decreased. She suggested that sugar peptized the molecules of gluten. Thus, the fact that a decreased amount of gluten was obtained as the levels of concentration of each sugar, ex- cept D (+) lactose, were increased may be due to: the sugars actually dissolving gluten protein; a decreased absorptive power of the flour proteins due to the presence of a sugar, particularly at the "critical concentration levels"; or the sugars exerting a peptizing action on the gluten protein. It is thought that the sugars did affect the structure of gluten balls as shown by increased volumes of the gluten balls when the sugars were added at the lower levels of 75 concentration. The crushing forces of the gluten balls were also noted to be smaller at these lower levels and would further indicate weakening in the structure of gluten. How- ever, as the concentrations of the sugars were increased, gluten yields became smaller and hence, the volumes and crushing forces of these baked gluten balls were less. SUMMARY AND CONCLUSIONS Two experimental procedures were employed in this study. An all—purpose flour was used throughout the study. In the first procedure 5% levels of D (-) fructose C.P., D (-) glucose C.P., beta-lactose 98%, D (+) technical maltose, and sucrose (cane sugar) were incorporated in: (a) a dough in the preparation of gluten, (b) gluten prepared from the : f preceding method, and (c) gluten made from only a flour-water dough. The effects of the three methods of adding the sugars and the effects of each sugar on gluten were determined by measuring the amount of resulting drip loss from the raw glu- ten, and the volumes and crushing forces of baked gluten balls. Gluten which had had no sugar additions served as a control for each method. Drip losses of gluten were greater when sugars were incorporated in the gluten after preparation. These drip losses, in addition to containing some of the added sugar in solution, were also shown to include nitrogenous material (positive ninhydrin test) presumably proteins, peptones, peptides or alpha-amino acids. It was concluded that the sugars exerted a peptizing or solvent action on the gluten :proteins when added to prepared gluten. Volumes of the gluten balls prepared by methods (a) or (b) were greater than the volumes of gluten balls prepared 76 77 by method (c). Individual analysis of the volumes of the gluten balls within each method revealed that the volumes of gluten balls prepared by methods (a) and (b) were not altered significantly by sugar additions. ln method (c), the gluten balls to which lactose or maltose had been added had signifi— cantly smaller volumes than control gluten balls or gluten balls to which fructose had been added. The volumes of gluten balls to which glucose or sucrose had been added did not differ significantly from control gluten balls or gluten balls which had had additions of fructose, lactose or maltose. The crushing forces of gluten balls prepared by method (a) were significantly greater than the crushing forces of gluten balls prepared by methods (b) or (c). It was concluded that a sugar addition to prepared gluten weakened the struc— ture of the baked gluten balls and hence, these gluten balls were more tender. The double sugar additions of method (b) weakened the structure of gluten balls to a significant ex- tent. In the second experimental procedure 5% increments of D (-) fructose C.P., D (-) glucose C.P., D (+) technical malt— ose, D (+) maltose C.P., beta—lactose 98%, D (+) lactose C.P., or“ sucrose (cane sugar) were added to a flour dough in the Iareparation of gluten. The effect of each sugar was followed byrrneasuring gluten yields, and the volumes and crushing forces of baked gluten balls. 78 No gluten was obtained when the following sugars were added at these "critical levels of concentration": fructose, glucose and sucrose, 55-65%; D (+) maltose C.P., 45%; beta- lactose, uO-u5%; and D (+) technical maltose 30%. The D (+) lactose seemingly did not affect gluten yield, even at the 70% concentration. The technical maltose had the most detrimental effect on gluten yields and on the volumes and crushing forces of baked gluten balls. Beta—lactose closely resembled the tech- nical maltose in its effects. The C.P. maltose was not as detrimental in its effect on the gluten yields and the volumes and crushing forces of baked gluten balls as the technical maltose, but it was more detrimental in its effect than was glucose, sucrose, fructose or D (+) lactose. The D (+) lac- tose did not affect gluten yields or the volumes or crushing forces of baked gluten balls. Results of the second experimental procedure indicate that the effect of a sugar on gluten formation may be related to the solubility of the sugar. The D (+) lactose seemed to be less soluble and, therefore, exerted no significant effects on gluten yields, and the volumes and crushing forces of baked gluten balls. It is suggested that all of the sugars, except D (+) lactx:se, either exerted a solvent or peptizing action on the gfluiten protein or decreased the water absorptive power of the glut£n1 proteins. Hence, as increasing increments of the sugars 79 were added less gluten was obtained and at "critical levels of concentration," no gluten was obtained. The volumes of gluten balls were greater than controls when the sugars were added at initial levels of concentration. The crushing forces of the gluten balls also decreased as in— creasing levels of sugars were added. These nayiltsindicated that the presence of a sugar in the dough from which the glu— ten was prepared had actually weakened the structure of baked gluten balls. However, as the concentration of the sugars in creased, the yields of gluten were less and hence, thevolumes of gluten balls were much smaller and forces needed to crush these gluten balls were less. IO. 11. 12. LITERATURE CITED ..Alsberg, C. L., and Griffing, E. P. The heat coagulation of gluten. Cereal Chem. g: ull-u23 (1927). Bailey, C. H. A translation of Beccari's lecture "Concern- ing Grain" (I728). Cereal Chem. IQ; 555-561 (l9ul). . Bailey, C. H. 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