Study on hydrolysis of soybean protein by protease from Bacillus natto

Hydrolysis process of soybean protein by protease from Bacillus natto was investigated.The effect of the main parameters including enzyme/subst rate ratio,soybean protein concentration,initial pH,hydrolysis time,and hydrolysis temperature were analyzed and the hydrolysis process was optimized with single factor experiment,fractional factorial design(FFD),central composite design(CCD)and response surface methodology.After optimization,the optimum hydrolysis process conditions were obtained:soybean protein concentration 4%,enzyme/subst rate ratio 3460u/g,initial pH 10.0,hydrolysis temperature 58℃ and hydrolysis time 8h.Under these optimized conditions,hydrolysis degree value of soybean protein could reach 38.08mg/g,and the yield of polypeptides was 66.5%.