Properties and molecular-structural features of enzymatically hydrolyzed proteins of pea isolate and secondary starch-protein product

The study examined the functional characteristics and molecular structure of the enzymatically hydrolyzed pea isolate and secondary starch-protein product obtained by enzymatic extraction of flour using domestic carbohydrases and protease. A relationship was established between the structural features of proteins, their functional properties and bioavailability. The isolate contained 94 % protein, had a light cream color and a slight pea flavor. Compared with the isolate obtained by traditional alkaline extraction, it had increased solubility (by 23.40 %), foaming capacity (by 35.56 %), fat-binding capacity (by 33.48 %), in vitro digestibility (by 11.79 %) and an increased content of β-bends in the protein structure (by 2.32 times). Urease activity in the isolate under study decreased 5 times in comparison with the original pea flour. Increased foaming capacity of the isolate proteins and decreased foam stability are associated with a high content of β-structures and a decrease in the number of α-helices. Increased porosity of the isolate protein particles contributed to an increase in its solubility in water and attackability by gastrointestinal enzymes, in comparison with the isolate obtained in the traditional way. The starch-protein product contained about 75 % starch and 10 % protein, had a milky color, a floury taste with a slight pea flavor. Also, in comparison with flour, the product had a split structure, increased protein digestibility in vitro (by 2.81 %), the content of α-helices in protein (by 67.90 %), β-bends (by 2.37 times) with a decrease in the amount of β-layer (by 10.12 times) and urease activity. Taking into account the achieved results, the pea isolate obtained by enzymatic extraction with Russian enzymes should be recommended as a protein ingredient in the production of plant-based drinks, food products with a foam system, and the starch-protein product — in the technology of manufacturing extrusion snacks.