Optimization of Enzymatic Hydrolysis Condition for Preparation of Antioxidant Peptides from Eel Processing By-product

The enzymatic hydrolysis condition for preparation of antioxidant peptides from eel processing by-products were optimized by response surface methodology. The results showed that, the relationship between the antioxidant capacity(Y which evaluated by the reducing power of hydrolysates) of enzymatic hydrolysates and three parameters for enzymatic hydrolysis(ratio of enzyme to substrate protein(X1), temperature(X2) and time(X3) for enzymatic hydrolysis) could be described with the following regression equation: Y=-2.77+ 0.26X1+0.097 1X2+0.32X3-0.001 27X1X2-0.015 3X1X3+0.000 658X2X3- 0.019 4X12-0.093 1X22-0.049X32. All the three independent variables had significant influences on the reducing power of enzymatic hydrolysates(P0.05), and the order of their effects was X1X3X2. And the interactions between X1and X2, and between X1and X3also had significant influences on the reducing power of enzymatic hydrolysates(P 0.05). Over-hydrolysis of the substrate protein decreased the antioxidant capacity of enzymatic hydrolysates. The optimum enzymatic hydrolysis conditions for preparation of antioxidant peptides from eel processing by-products were as follows: the ratio of enzyme to substrate protein was 3.84%, the temperature of enzymatic hydrolysis was 50.6 ℃, and 3 h for hydrolysis. The optimized parameters of enzymatic hydrolysis were verified by 6 duplicated experiments. No significant difference between the predicted reducing power and the actual reducing power of enzymatic hydrolysates was found. And the EC50of DPPH radical scavenging of the enzymatic hydrolysates was 0.32 mg/mL.