Wheat proteins general

Dietary protein sources differ widely in their proportions of the EAA. In general, complete proteins (those containing sufficient quantities of EAA) are of animal origin (e.g., meat, milk, and eggs). Plant proteins often lack one or more EAA. For example, gliadin (wheat protein) has insufficient amounts of lysine, and zein (com protein) is low in both lysine and tryptophan. Because plant proteins differ in their amino acid compositions, plant foods can provide a high-quality source of essential amino acids only if they are eaten in appropriate combinations. One such combination includes beans (low in methionine) and cereal grains (low in lysine). 

The reaction is not limited to amino acids but can be extended to proteins in general [27,28]. For example, hydrolyzed wheat protein can be cross-linked with siloxane chains. These products are obtained by the reaction of epoxide or anhydride groups of organo-modified polysiloxanes with amino groups of the protein. 

This is a tetraploid wheat with generally yellow vitreous endosperm used for the industrial production of long and short pastas. It contains from 10%-17% of protein. 

Soft-wheat flours are sold for general family use, as biscuit or cake flours, and for the commercial production of crackers, pretzels, cakes, cookies, and pastry. The protein in soft wheat flour mns from 7 to 10%. There are differences in appearance, texture, and absorption capacity between hard- and soft-wheat flour subjected to the same milling procedures. Hard-wheat flour falls into separate particles if shaken in the hand whereas, soft-wheat flour tends to clump and hold its shape if pressed together. Hard-wheat flour feels slightly coarse and granular when mbbed between the fingers soft-wheat flour feels soft and smooth. Hard-wheat flour absorbs more Hquid than does soft-wheat flour. Consequently, many recipes recommend a variable measure of either flour or Hquid to achieve a desired consistency. 

Field Pea Flours in Bread Products. Legume flours, particularly soy, have long been incorporated into wheat-based products, both for their functional effects and for protein fortification. In general, increasing the levels of legume flours results in decreased loaf volume, lower crumb grain quality, and adverse flavor characteristics in the baked bread (Table III). 

Cake Donuts. The effects of 0-30% substitution of dry-roasted air-classified navy, pinto or black protein flour for wheat flour on the physical and sensory qualities of cake donuts were investigated. In general, fat absorption decreased as the level of substitution increased with the pinto bean variable having the lowest values. An increase of navy bean and pinto protein levels decreased donut height after the 10% level. The donuts with pinto bean protein exhibited less spread than the other bean type donut variables. Navy bean protein produced a more tender donut than the other bean types. The control donut and those with navy bean protein were the lightest in color, followed by pinto and black bean protein donuts,... 

The best method for evaluation of the color problem is to prepare a food product containing the protein flour. Biscuits were routinely used as the model food system. Figure 5 illustrates the color of biscuits prepared with lOOZ wheat flour and with 20Z plant-protein products. The color of the biscuits prepared with soybean and peanut flours shows that these ingredients do not cause a serious color problem. However, sunflower, alfalfa leaf, and cottonseed flours do produce a discoloration in this model food system. The L and b values generally reflect this visual evaluation. 

Sufficient protein can generally be obtained in a vegetarian diet by combining a legume, such as peas or beans, with a grain, such as wheat or corn. Familiar meals containing such a combination include a peanut butter sandwich, corn tortillas and refried beans, and rice and toffi. 

Identification of oat (Avena) cultivars by HPLC was first reported by Lookhart and coworkers (153-155) in combined electrophoresis/HPLC experiments. The HPLC technique used was a modification of the procedure described by Bietz (137) for wheat. Generally, the prolamin fraction, i.e., the alcohol-soluble fraction, of oat species generates complex polyacrylamide gel-electrophoresis (PAGE) and RP-HPLC patterns, with increasing complexity as ploidy of the selections increased. Readily (visible) identification of the cultivars was possible only when PAGE and RP-HPLC results were combined. An HPLC procedure for the characterization of the major oat protein fractions was developed by Lapvetelainen et al. (156). Salt-soluble, alcohol-soluble, and alkali-soluble protein fractions were extracted with 0.1 M NaCl, 52% ethanol, and 1% SDS in 0.05 M borate (pH 10), respectively. For the five cultivars examined, RP-HPLC separations of salt- and alkali-soluble proteins were very similar, whereas the prolamin fraction enabled culti-var differentiation, except for very closely related cultivars. 

Several other proteins that bind emulsifiers follow the general trends of this model. For example, the properties of the lipid binding protein from wheat called puroindoline has broadly similar properties [15]. 

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