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Optimization of enzymatic hydrolysis parameters for antioxidant capacity of peptide from sea cucumber(Stichopus horrens) viscera

In order to increase the utilization value of sea cucumber(Stichopus horrens) viscera as a potential source of peptides, protamex was selected for the hydrolysis of sea cucumber viscera. One-factor-at-a-time method was used to investigate the effects of temperature, p H, enzyme dosage, and hydrolysis time on hydrolysis degree. Following these investigation, a quadratic regression model describing hydrolysis degree as a response to s temperature, p H, enzyme dosage, and hydrolysis time was set up using a Box-Behnken experimental design. As demonstrated by the results analysis of variance and validation experiments, the model could well indicate the hydrolysis degree of sea cucumber viscera. The optimal hydrolysis conditions of temperature, p H, enzyme dosage, and hydrolysis time were determined to be 52.66℃, 6.71, 2.5%(dry mass ratio) and 10 hour, respectively. Under these conditions, the hydrolysis degree of sea cucumber viscera is 49.58%. Under the best condition of enzymatic hydrolysis, more than 74% of the peptides were less than 500 Da. The antioxidant activity of peptides was measured by DPPH method, showing that the radical scavenging activity is 24.8% when the concentration was about 3 mg/m L. The antioxidant activity of peptides was measured by ABTS method, showing that the Vitamin C Equivalent Antioxidant Capacity is 0.255 μmol/g when the concentration was about 3 mg/m L.