Abstract
Proteins from vegetable and cereal sources are an excellent alternative to substitute animal-based counterparts because of their reduced cost, abundant supply and good nutritional value. The objective of this investigation is to study a set of vegetable and cereal proteins in terms of physicochemical and functional properties. Twenty protein sources were studied: five soya bean flour samples, one pea flour and fourteen newly developed blends of soya bean and maize germ (five concentrates and nine hydrolysates). The physicochemical characterization included pH (5.63 to 7.57), electrical conductivity (1.32 to 4.32 mS/cm), protein content (20.78 to 94.24% on dry mass basis), free amino nitrogen (0.54 to 2.87 mg/g) and urease activity (0.08 to 2.20). The functional properties showed interesting differences among proteins: water absorption index ranged from 0.41 to 18.52, the highest being of soya and maize concentrates. Nitrogen and water solubility ranged from 10.14 to 74.89% and from 20.42 to 95.65%, respectively. Fat absorption and emulsification activity indices ranged from 2.59 to 4.72 and from 3936.6 to 52 399.2 m2/g respectively, the highest being of pea flour. Foam activity (66.7 to 475.0%) of the soya and maize hydrolysates was the best. Correlation analyses showed that hydrolysis affected solubility-related parameters whereas fat-associated indices were inversely correlated with water-linked parameters. Foam properties were better of proteins treated with low heat, which also had high urease activity. Physicochemical and functional characterization of the soya and maize protein concentrates and hydrolysates allowed the identification of differences regarding other vegetable and cereal protein sources such as pea or soya bean.
Highlights
There is a rising interest in protein isolation for their subsequent use as food ingredient
The electrical conductivity (EC) of soya and maize concentrates ranged from 2.47 to 3.64 mS/cm, comparable to the results reported by Režek Jambrak et al [28] of 3.28 mS/cm of a soya protein concentrate
This research characterized and compared chemical and functional properties of some vegetable and cereal proteins including commercial and new protein concentrates and hydrolysates obtained from a mixture of soya bean and maize germ
Summary
There is a rising interest in protein isolation for their subsequent use as food ingredient. Half of adults perceive proteins as ingredients that increase energy levels, support overall good health and improve muscle tone. These macronutrients are considered important in diets aimed to complete a weight management program. The protein industry is segmented into animal (gelatin, egg white, casein and whey) or vegetable, of which soya bean is the only source of worldwide relevance. The former has the advantage of being of high nutritional quality, but with higher cost than the vegetable counterparts and frequently the supply is irregular and unreliable.
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