| With soybean protein isolate as raw material, soybean peptide was prepared by ultrasound-assisted complex enzyme enzymolysis. On the basis of single factor experiment, with dosage of complex enzyme, enzymolysis time, enzymolysis temperature, and enzymolysis pH as independent variable, soybean peptide yield as response value, the effects of every independent variable as well as their interaction on the soybean peptide yield were researched by response surface methodology. The relative molecular weight of the soybean peptide was determined. The results showed that the effect of enzymolysis temperature on soybean peptide yield was the strongest, followed by dosage of complex enzyme, enzymolysis time and enzymolysis pH. The optimal ultrasound-assisted complex enzyme enzymolysis conditions were obtained as follows: ultrasonic power 180 W, ultrasonic time 10 min, ultrasonic temperature 35?℃, mass ratio of alkaline protease to neutral protease 3∶?1, dosage of complex enzyme 2.04%, enzymolysis time 40 h, enzymolysis temperature 59?℃ and enzymolysis pH 8.0.Under these conditions, the soybean peptide yield was 63.27%, and the relative molecular weight of most soybean peptide was below 1 000. |
