Complex bioconversion of secondary products of processing pea flour into fodder yeast

Abstract

The purpose of the research is to develop a comprehensive bioconversion of secondary processing products (SPP) of pea flour: liquid whey and insoluble starch-protein residue (ISPR), formed during the isolation of food protein concentrate (PC) using various enzyme preparations. The research was carried out in 2021-2023. The bioconversion of whey and ISPR into fodder yeast (FY) was performed with the association of cultures of S. cerevisiae 121 and G. candidum 977 (1:1). There was created a mathematical model of the dependence of biomass growth on whey on technological factors, and the optimal parameters were determined: pH, temperature, amount of inoculum. In the process of biomass synthesis microorganisms absorbed glucose, xylose, galactose, fructose from whey. The parameters of ISPR hydrolysis and the conditions for its joint bioconversion with whey with the same microorganisms were established: the amount of residue added to the mass of whey, pH, temperature, process duration, pressure. With insoluble starch-protein residue hydrolyzed at pH 1.8, the amount of protein in the biomass increased by 2.2 times, reducing sugars – by 6.1 times, compared with the original whey. At the same time, glucose and maltose were absorbed. Dry FYs contained 51.09-61.68 % protein, 2-8 % lipids, and ash content 5-8 % per dry matter. The amino acid score of proteins was 90-247 %, the ratio of saturated (23.5 %) and unsaturated fatty acids (71.67 %) – 1:3, omega-6 fatty acids – 19.73 %, trans-isomers – 5.0 %. Yeast is rich in sodium, potassium, calcium, magnesium, zinc. The mass fraction of nucleic acids and heavy metals in FYs were within the normal range, in vitro digestibility was 85.73-89.74 %. The data indicated the expediency of utilization of pea flour secondary processing products into high-quality FY by comprehensive bioconversion.