Optimization of Preparation Technology and Antioxidant Activity of Schisandrae chinensis Protein Peptides in Vitro by Response Surface Methodology

Objective: To obtain the optimal enzyme and preparation process for Schisandra chinensis protein peptides and investigate its in vitro antioxidant activity. Methods: Seven proteases were used to hydrolyze Schisandra chinensis protein. Based on the degree of hydrolysis, free radical scavenging activity, polypeptide yield and content of different hydrolysates of Schisandra chinensis protein and the comprehensive evaluation of molecular weight in SDS-PAGE, the optimal protease was screened. The DPPH free radical scavenging rate was used as the index, and the optimal enzymatic hydrolysis process was determined by single factor test combined with response surface analysis. The scavenging ability of O₂⁻·, ·OH, DPPH·, ABTS⁺·, Fe²⁺ chelating ability and Fe³⁺ reducing ability of Schisandrae chinensis protein peptides were analyzed and compared with Schisandra chinensis protein. Results: The optimum enzyme for the preparation of Schisandra chinensis protein peptides was alkaline protease. The optimum enzymatic hydrolysis parameters were as follows: substrate concentration 5%, enzyme-to-substrate ratio 1%, enzymatic hydrolysis time 3 h, enzymatic hydrolysis temperature 55 ℃, pH9.0. Under these conditions, the polypeptide content was 88.61%, the degree of hydrolysis was 24.21%, and the DPPH· scavenging rate was 86.96%. The free radical scavenging ability and reducing ability of Schisandrae chinensis protein peptides were better than those of Schisandrae chinensis protein. Conclusion: This study determined the optimum enzyme and hydrolysis process of Schisandrae chinensis protein peptides, and pointed out that Schisandrae chinensis protein peptides had better antioxidant activity in vitro and could be used as a natural antioxidant.