Legume proteins, functionality

Characteristically, legume seeds are rich in protein and contain intermediate to high levels of lysine and threonine which are important in balancing the deficiencies of these essential amino acids in cereal diets. Certain legume proteins, such as soybean, also exhibit strong functional properties, especially water solubility, water and fat binding and emulsification. Thus soybean flours, protein concentrates and isolates have been used widely as nutritional supplements and functional ingredients in foods. 

Indeed a recent report to the National Science Foundation on Protein Resources and Technology recommends the study of the modification of the functionality of oilseeds and legume proteins by physical, chemical, and enzymatic methods to facilitate development of protein materials with wide versatility and acceptability in formulated foods (I). 

Wieser, H., Seilmeier, W, Belitz, H.-D. Use of RP-HPLC for a better understanding of the structure and the functionality of wheat gluten proteins. In High-Performance Liquid Chromatography of Cereal and Legume Proteins (Eds. Kruger, J.E., Bietz, J.A.), p. 235, American Assodation of Cereal Chemists St. Paul. Minn., 1994... 

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). 

Whole oilseeds and legumes and their derivatives (defatted flours, and protein concentrates and isolates) are used in traditional foods as sources of protein and for their texture-modifying functions. This article reviews, on a comparative basis, processes for preparation of vegetable food proteins, compositions and characteristics of the resulting food ingredients, and their functionalities and uses in traditional foods. 

Composition and Functionality of Protein, Starch, and Fiber from Wet and Dry Processing of Grain Legumes... 

Functional Properties. The pH s of the flours and products obtained by air classification varied between 6.5-6.7 (Table III), which was typical of legume flours (1.3). The proteinates were near oH 7 because of the neutralization orocedure after isoelectric orecioita-tion while the refined starch and fiber were still alkaline in pH despite several washings with distilled water. In a previous study, adjustment of the pH of lupine flour was shown to have a significant influence on functional properties (1) but pH was not adjusted in the present investigation. 

Like NSI, the oil absorption capacities of the legume flours were decreased by pin milling, and the protein fractions were more functional in this parameter than were the starch fractions... 

About 300 different non-protein amino acids occur in plants. They may be incorporated into proteins in place of the correct amino acids. If they are incorporated into enzymes, they can prevent them from functioning. This often leads to death of the animal. For example, azetidine 2-carhoxylic acid in lily-of-the-valley, Comallaria majalis, and several legumes interferes with synthesis or utilization of structurally similar proline (Fig. 11.9). 

Zinc plays a number of important roles in the body and deficiency results in serious adverse effects. Recommended daily intake is 12 to 15 mg. Zinc is very common in the environment and readily available in many foods, including grains, nuts, legumes, meats, seafood, and dairy products. Numerous enzymes require zinc, as do proteins that regulate gene expression. Zinc plays a role in the immune system and is also important in the development and function of the nervous system. 

HI4 OMT protein showed activity against the 3-hydroxyl of a compound related to (+)-6a-hydroxymaackiain, ( + )-medicarpin, suggesting HM OMT may be functionally identical to HM30MT. However, the HM30MT substrate is only found in species making (+)-pisatin. The G. echinata HM OMT cDNA was used to isolate HM OMT cDNAs from L. japonicus, M. truncatula, and other legumes. Both HM OMT and lOMT may be involved in formono-netin biosynthesis, perhaps in the same tissues, and the formation of heterodimers of similar OMTs has been reported. 

Makri, E., Papalamprou, E., Doxastakis, G. (2005). Study of functional properties of seed storage proteins from indigenous European legume crops (lupin, pea, broad bean) in admixture with polysaccharides. Food Hydrocolloids, 19, 583-594. 

We have chosen to discuss enzyme modification of proteins in terms of changes in various functional properties. Another approach might have been to consider specific substrates for protease action such as meat and milk, legumes and cereals, and the novel sources of food protein such as leaves and microorganisms ( ). Alternatively, the proteases themselves provide categories for discussion, among which are their source (animals, plants, microorganisms), their type (serine-, sulfhydryl-, and metalloenzymes), and their specificity (endo- and exopeptidases, aromatic, aliphatic, or basic residue bond specificity). See Yamamoto (2) for a review of proteolytic enzymes important to functionality. 

The Rhizobium-legume symbiosis, an interaction between a prokaryote (Rhizobium) and a eukaryote (legume), requires a series of sequential induction and function of both bacterium-encoded (bac-teroidins) and host-encoded (nodulins) nodule-specific proteins. It has been shown that many plant (Peters et al., 1986 Firmin et al., 1986 Djordjevic et al., 1987 Sadowsky et al., 1988 see also Peters Verma,... 

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