Step-by-step Enzymatic Hydrolysis Preparation of Soybean Peptide with Ultrasonic-Assisted Method

The ultrasonic treatment and step-by-step enzymatic hydrolysis method was utilized to improve the hydrolysis of soy peptides.The suitable time,power and temperature of ultrasonic treatment were investigated with soluble protein content as index.Then the neutral protease and papain were used as tool enzyme to hydrolyze soybean meal step-by-step,and the effect of substrate concentration,temperature,pH,enzyme concentration,hydrolysis time on peptide yield was researched.Results showed the best process parameters of the ultrasonic pre-treatment were 35℃,10 min,210 W.The optimized conditions of neutral protease hydrolysis were hydrolyzed at 45℃,pH 8.0 for 3 h with the substrate concentration of 6% and enzyme concentration of 10 000 U·g-1,the hydrolysis degree and peptide yield reached 19.45% and 20.51%,respectively.The optimized conditions of papain hydrolysis were hydrolyzed at 55℃,pH 10.5 for 3.5 h with the enzyme concentration of 12 500 U·g-1,the hydrolysis degree and peptide yield reached 30.89% and 48.79%,respectively.After step-by-step enzymatic hydrolysis,peptide yield and the added value of the soybean meal were increased.