Effect of Two-Step Fermentation by Rhizopus oligosporus and Bacillus subtilis on Protein of Fermented Soybean

The objective of this study was to investigate effect of the steamed soybeans inoculated with Rhizopus oligosporus in advance then Bacillus subtilis on the protein of fermentd soybeans. Soluble nitrogen content and degree of hydrolysis of soy protein increased with increasing fermenting time both of the two-step fermentation and single starter culture of B. subtilis. The amino acid composition of the two-step fermented product fluctuant during fermentation, of which glutamic and aspartic acids had the highest content. However, The most bands of soy protein components with molecular weight above 20 kDa on electrophoretogram of the product by the two-step fermentation became faint. It meant the concentration of these proteins decreased after 24 h of fermentation.