PROTEIN QUALITY IMPROVEMENT AND ANTI-NUTRITIONAL FACTORS REDUCTION IN SOYBEAN MEAL BY Bacillus velezensis K1

Abstract

The solid-state fermentation (SSF) of soybean meal (SBM) by Bacillus velezensis K1 to improve protein quality and reduce allergenic proteins as well as raffinose family oligosaccharides was investigated in this research paper. The fermentation parameters affected protein hydrolysis, namely soybean meal moisture, size of inoculums, time and temperature of fermentation were evaluated in the soybean meal. The best solid-state fermentation conditions with the highest degree of hydrolysis (16.65 ± 4.08%) were 50% (w/w) moisture content, 10% (v/w) inoculum size, 40°C and 72 hours fermentation. Under these optimal conditions, large proteins in the soybean meal were hydrolysed. Proteins with molecular weight <10 kDa increased significantly from 34.05 to 48.22% (P<0.05). Additionally, allergens (glycinin and β-conglycinin) and raffinose family oligosaccharides decreased. The bands representing glycinin and β-conglycinin on SDS-PAGE were considerably reduced and their degradations were 96.47% and 49.60%, respectively. The raffinose family oligosaccharides, primarily stachyose and raffinose also decreased by 73.57% and 22.76%, respectively. With the capability of producing protease and other carbohydrate hydrolytic enzymes (cellulase, pectinase, amylase and invertase), B. velezensis K1 presents great potential for increasing the nutritional quality of the soybean meal as an ingredient in the feed industry.