EVALUATION OF FOUR SORGHUM HYBRIDS THROUGH THE ...

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are added as adjustments to leavening agents may be needed (Serna-Saldivar and others, 1988). Reducing Agents Reducing agents break disulfide bonds in gluten and can impact protein properties. Disulfide bonds affect dough recovery and stretching. When reducing agents are added the dough is more extensible and less elastic improving dough machineability (Serna-Saldivar and others 1988). L-cysteine, sodium bisulfites, and sodium metabisulfites are common reducing agents (Qarooni 1993). Oxidizing Agents Die-cut operations may add oxidizing agents to increase the mixing stability as dough is reworked. Ascorbic acid and potassium bromate are examples of oxidizing agents for die-cut flour tortillas (Serna-Saldivar and others 1988). Structure Development Gluten Functionality Among cereal flours, wheat flour is the only flour that can form a strong, cohesive dough with gas retention capabilities. This viscoelastic property is what sets wheat apart from the other cereal flours. The source of this function is essentially from hydrated gluten (Pyler 1988). Isolated gluten is about 80% protein and 8% lipids on a dry basis, with the residual 12% being ash and carbohydrate (Hoseney 1994a; Pyler 1988). The gluten proteins are believed to be responsible for the cohesive, viscoelastic characteristic as well as gas retention. The two proteins in gluten are gliadin and glutenin, each at approximately half the total composition (Hoseney 1994a). 33
Gliadin, which is a prolamin characterized by being soluble in aqueous alcohols, has a molecular weight between 30,000 to 100,000 (Pyler 1988). When gliadins are isolated and hydrated, a viscous, fluid mass is produced. Isolated glutenins, on the other hand, produce a very tough, rubbery mass when hydrated. The extensibility (i.e., ability to stretch without breaking) of a wheat dough is affected by the total amount of glutenin in the flour (Macritchie 1992). Glutenins are often classified as glutelins as they are insoluble in aqueous alcohols, but are soluble in dilute acetic acid. The molecular weight ranges from 100,000 to several million. This large tertiary structure is due to the presence of inter-molecular disulfide bonds. These disulfide bonds have created an area of study in gluten development known as the disulfide-sulfhydryl interchange reaction. The function of this interchange reaction in gluten development continues to be a controversial topic. Effects on the rheological properties of dough have been observed when using disulfide bond reducing agents, sulfhydryl oxidizing agents, and sulfhydryl blocking agents (Macritchie 1992). However, the purpose of sulfur-containing amino acid residues in dough development has not been successfully explained through experimental research (Bloksma and Bushuk 1988; Pomeranz 1988). Although the intricate bonding that takes place in gluten is extremely important in discussing functionality, the glass transition temperature must be taken into account. A glass transition is a large change in modulus at a certain temperature for a particular material. At the right temperature, the polymers go from a leathery state to a rubbery state. Gluten with 16% water has a glass transition temperature at room temperature. This property explains gluten’s ability to form a unique dough while mixing. Other 34
Page 1 and 2: EVALUATION OF FOUR SORGHUM HYBRIDS
Page 3 and 4: compared to a gluten-free wrap alre
Page 5 and 6: Flour Characterization Starch Isola
Page 7 and 8: Chapter 1 LIST OF FIGURES 1. Mechan
Page 9 and 10: 4. Comparison of color, pH, water a
Page 11 and 12: ACKNOWLEDGMENTS I cannot begin to t
Page 13 and 14: most important. As a continent, Afr
Page 15 and 16: Before this act, ingredients in foo
Page 17 and 18: Mechanism of Actions According to B
Page 19 and 20: symptoms similar to allergic reacti
Page 21 and 22: Table 1. Symptoms of Celiac Disease
Page 23 and 24: Treatment If an individual is diagn
Page 25 and 26: MARKET FOR GLUTEN-FREE PRODUCTS In
Page 27 and 28: This exported sorghum may be used f
Page 29 and 30: sorghum, White sorghum, and Mixed s
Page 31 and 32: The actual proportion of the three
Page 33 and 34: fiber (Bach-Knudsen and Munck 1985)
Page 35 and 36: preference towards white sorghums w
Page 37 and 38: cassava starch, and raw cassava sta
Page 39 and 40: (about 5 min.). Waniska and others
Page 41 and 42: easily. These tortillas are best fo
Page 43: starch, and leavening acids, is a c
Page 47 and 48: gluten matrix can hold some of the
Page 49 and 50: LITERATURE CITED Aboubacar A, Hamak
Page 51 and 52: Federal Register. 2007. Food Labeli
Page 53 and 54: Murty DS, Singh U, Suryaprakash S,
Page 55 and 56: Subramanian V, Jambunathan R, Suury
Page 57 and 58: Chapter 2: Grain and Flour Characte
Page 59 and 60: Introduction: An estimated 1-2 perc
Page 61 and 62: The cleaned grain was then analyzed
Page 63 and 64: Starch Particle Size Distribution:
Page 65 and 66: Moisture Content: The moisture cont
Page 67 and 68: products. Grain hardness can also b
Page 69 and 70: Flour Characterization Flour Partic
Page 71 and 72: Starch Particle Size Distribution:
Page 73 and 74: Total Starch: The total starch cont
Page 75 and 76: Table 4. Comparison of total starch
Page 77 and 78: 66 Table 5. Comparison of starch pa
Page 79 and 80: create a flour of a specific ash co
Page 81 and 82: Conclusions: This study has shown t
Page 83 and 84: Evers AD, Stevens DJ. 1985. Starch
Page 85 and 86: Schober TJ, Bean SR, Boyle DL. 2007
Page 87 and 88: Abstract Gluten-free flour tortilla
Page 89 and 90: following five states in ranking or
Page 91 and 92: increased. This is probably due to
Page 93 and 94: than a typical tortilla process. Ov
Page 95 and 96:
Table 1. Formulation for sorghum fl
Page 97 and 98:
of 1.00 mm/s, test speed of 1.00 mm
Page 99 and 100:
values. Calibration was performed b
Page 101 and 102:
flour to use was determined by memb
Page 103 and 104:
Table 2. Comparison of weight, diam
Page 105 and 106:
Also, starch damage was found to be
Page 107 and 108:
Color: Significant differences were
Page 109 and 110:
98 Table 4. Comparison of color, pH
Page 111 and 112:
3.83 (TVM) to 8.00 (F-625). Grittin
Page 113 and 114:
102 Table 6. Comparison of texture
Page 115 and 116:
104 Table 8. Comparison of texture
Page 117 and 118:
Table 9. Comparison of scores from
Page 119 and 120:
REFERENCES Bejosano FP, Joseph S, L
Page 121 and 122:
Appendices 110
Page 123 and 124:
Appendix 2. Average starch particle
Page 125 and 126:
Appendix 4. RVA curve for F-1000. 1
Page 127 and 128:
Appendix 6. RVA curve for 5040C. 11
Page 129 and 130:
118 Appendix 8. RVA curve for TVM.
Page 131 and 132:
TEXTURE (in the hand) Roughness: Th
Page 133 and 134:
Hardness: The relative resistance t
Page 135 and 136:
Appendix 11: CONSUMER PRE-SCREENING
Page 137 and 138:
SAMPLE: 571 Please check only one b
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