Mechanically activated hydrolysis of plant-derived proteins in food industry

Abstract

A poor consumption of important nutrients triggered a public interest in functional foods that contain easy-to-digest proteins. The present research features fractionation, mechanical activation, and enzymatic hydrolysis of pea protein. According to modern chemical methods, the protein content in the original pea biomass was 24.3% and its molecular weight distribution (MWD) was 5–135 kDa. Fractionation, or protein displacement, resulted in four fractions of biopolymers with different chemical composition, i.e. a different content of protein and carbohydrate molecules. The paper introduces some data on the enzymatic transformations of the substrate. A set of experiments made it possible to define the optimal conditions for the mechanical activation of pea biomass with proteolytic enzymes. The enzymes were obtained from Protosubtilin G3x, a complex enzyme preparation. When the substrate and the enzymes were mechanically activated together, it produced mechanocomposite, an intermediate product with increased reactivity. It increased the specific surface area by 3.2 times and doubled the crystallinity of the substrate. As a result, the rate and yield of the subsequent enzymatic hydrolysis increased from 18% to 61%. The study determined the capacity of the substrate in relation to the enzyme preparation. Under optimal conditions, the pea hydrolysis destroyed protein molecules within two hours. After four hours of hydrolysis, no changes were detected. A polyacrylamide gel electrophoresis revealed non-hydrolysed protein molecules with MW ≈ 20 kDa. Presumably, they corresponded with legumin, which is resistant to neutral and alkaline proteases. The resulting hydrolysates were spray-dried to test their potential use as a food component. The product obtained by spray-drying had a monomodal distribution of particle sizes of spherical shape with adiameter of 5–20 μm.