Optimization of Enzymatic Hydrolysis Conditions for Preparation of Gingko Peptides from Ginkgo Nuts

Abstract

Ginkgo nuts were used as raw material and peptides were prepared in turn with Neutral protease and Flavourzyme. In single-factor experiments of Neutral protease, conditions of temperature, pH, enzyme concentration and substrate concentration were optimized in term of degree of hydrolysis (DH). Based on the results of single-factor experiments, an orthogonal experiment (L9(3)4) was conducted to optimize the hydrolysis conditions of Neutral protease. The results showed that enzyme concentration, substrate concentration, reaction temperature and initial pH were the main variables that influenced DH. The highest DH was obtained when hydrolysis time, reaction temperature, initial pH, enzyme amount and substrate concentration were 4 h, 45 oC, 7.0, 1.8 mg/mL and 0.02 g/mL, respectively. Subsequently, the resulting solution was further hydrolyzed with Flavourzyme. Initial pH, temperature, time and enzyme concentration were optimized in term of DH. Finally, another orthogonal experiment (L9(3)4) was conducted to get the best enzymatic conditions of Flavourzyme, and enzyme concentration, initial pH, temperature and time were used as factors. The results showed that when Flavourzyme concentration, reaction temperature, initial pH and hydrolysis time were 9.0 mg/mL, 50 oC, 7.0 and 5 h, respectively, DH was the highest. The final degree of hydrolysis was 22.56%.