Extractability, extractable protein compositions, technological-functional properties of pea (Pisum sativum) proteins from six genotypes grown in Serbia were investigated. Also, the relationship between these characteristics was presented. Investigated genotypes showed significant differences in storage protein content, composition and extractability. The ratio of vicilin:legumin concentrations, as well as the ratio of vicilin + convicilin: Legumin concentrations were positively correlated with extractability. Our data suggest that the higher level of vicilin and/or a lower level of legumin have a positive influence on protein extractability. The emulsion activity index (EAI) was strongly and positively correlated with the solubility, while no significant correlation was found between emulsion stability (ESI) and solubility, nor between foaming properties and solubility. No association was evident between ESI and EAI. A moderate positive correlation between emulsion stability and foam capacity was observed. Proteins from the investigated genotypes expressed significantly different emulsifying properties and foam capacity at different pH values, whereas low foam stability was detected. It appears that genotype has considerable influence on content, composition and technological-functional properties of pea bean proteins. This fact can be very useful for food scientists in efforts to improve the quality of peas and pea protein products.

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Due to high nutritive quality, good techno-functional properties and low cost, legume protein products are becoming the most appropriate alternative to protein products of animal origin. In food industries, these products are usually used as techno-functional additives which provide specific characteristics of final food products. Legume proteins are commonly used as flour, concentrates, and isolates. The greatest application on industrial scale has soy proteins, and to a lesser extent, in the past 20 years, pea protein isolates. The modest use of pea protein is partly a result of insufficient information relating to their techno-functional properties. This paper is an overview of techno-functional properties of pea proteins and their isolates. Also, the paper deals with the possible use of limited enzymatic hydrolysis as a method for the improvement of their techno-functional properties.2 tein isolates, whereas some other (5,13,14) pointed out better properties of pea isolates. Variations in the results among different studies could be due to the differences in the protein purity of the studied samples, method of protein isolation, the specific conditions used for the tests, as well as the different processing conditions (7,15). Furthermore, significantly different functionalities among pea isolates were observed. Maninder et al. (16) and Barac et al. (6,17) attributed this to the different ratio of the major proteins, which is in turn influenced by genotype characteristics, environmental conditions, and processing conditions (10,(18)(19)(20). To avoid the difference caused by different processing conditions, Barac et al. (15) prepared and compared pea, soybean and adzuki isolates under the same conditions. The results of this investigation showed that techno-functional properties of the isolates prepared from different species depended on several factors such as: choice of species and varieties, preparation conditions, and the pH value at which specific properties were tested. STORAGE PEA PROTEINSPea seeds contain about 22-23% proteins. The majority of pea proteins are globulins and albumins, which represent about 80% of total seed protein content. Albumins represent 18-25% and globulins 55-65% of total proteins (21). All globulins and some of albumins are storage proteins, which are used as nitrogen sources for the new embryos after seed germination (22).Major pea storage proteins, legumin, vicilin and convicilin are globulins and represent 65-85% of total proteins (23). According to sedimentation properties these proteins are classified into two fractions, 7S (vicilin, convicilin) and 11S fraction (legumin). Molecular forms of the three major proteins are presented in Figure 1. Figure 1. Molecular forms of legumin, vicilin and convicilin (22) APTEFF, 46, 1-269 (2015) 6 Alternatively, the isoelectric precipitation step can be substituted by ultrafiltration. The use of ultrafiltration increases the yield of isolates and change their composition. Isolates prepared by ultrafiltration contain 90-94% of protei...

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The aim of this work was to compare functional properties including solubility, emulsifying and foaming properties of native and thermally treated adzuki, soy and pea protein isolates prepared under the same conditions. These functional properties were tested at four pH values: pH 3.0, pH 5.0, pH 7.0 and pH 8.0. The lowest solubility at all pH values were obtained for isolate of adzuki whereas isolates of soybean had the highest values at almost all pHs. Thermal treatment reduced solubility of soy and pea isolates at all pH values, whereas solubility of adzuki isolate was unchanged, except at pH 8. Native isolate of adzuki had the best emulsifying properties at pH 7.0 whereas at the other pH values some of native pea and soybean protein isolates were superior. After thermal treatment, depending on tested pH and selected variety all of three species could be a good emulsifier. Native soy protein isolates formed the most stable foams at all pHs. Thermal treatment significantly improved foaming properties of adzuki isolate, whereas reduced foaming capacity of soy and pea isolates, but could improve foam stability of these isolates at specific pH. Appropriate selection of legume seed as well as variety could have great importance in achievement of desirable functional properties of final products. All three tested species could find specific application in wide range of food products.

Protein quality in six soybean varieties, based on subunit composition of their protein, was correlated with quality of the produced tofu. Also, protein changes due to a pilot plant processing method involving high temperature/pressure and commercial rennet as coagulant were assessed. In each soybean variety, glycinin (11S) and β-conglycinin (7S) as well as 11S/7S ratio significantly changed from beans to tofu. Between varieties, the 11S/7S protein ratio in seed indicated genotypic influence on tofu yield and gel hardness (r = 0.91 and r = 0.99, respectively; p < 0.05). Also, the 11S/7S ratio correlated with soymilk pH (r = 0.89, p < 0.05), leading to a relationship between soymilk pH with protein recovery and yield of tofu (r = 0.94 and r = 0.91, respectively; p < 0.05). The soybean β'-subunit of 7S protein negatively influenced tofu hardness (r = -0.91, p < 0.05). Seed protein composition and proportion of 7S protein subunits under the applied production method had an important role in defining tofu quality.

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Summary The aim of this study was to investigate the effects of partial enzymatic hydrolysis on functional properties of two different pea protein isolates obtained from two pea genotypes, Maja and L1. Papain and commercial protease (Streptomyces griseus protease) were used for protein modification. Solubility, emulsifying and foaming properties were estimated at four different pH values (3.0, 5.0, 7.0 and 8.0). Papain increased solubility of L1 pea protein isolate at pH 3.0, 5.0 and 8.0, emulsifying properties and foaming capacity at all pH values. Otherwise, papain increased solubility of Maja pea protein isolate only at pH 8.0. This pea protein isolate modified with both enzymes formed emulsions with improved stability at lower pH (3.0, 5.0). The commercial protease‐prepared pea protein isolates showed generally low solubility and different emulsifying and foaming properties. Proper selection of enzyme, conditions of hydrolysis and genotypes could result in production of pea protein isolates with desirable functional properties.