Synthesis and in vitro antioxidant functions of protein hydrolysate from backbones of Rastrelliger kanagurta by proteolytic enzymes

Every year, a huge quantity of fishery wastes and by-products are generated by fish processing industries. These wastes are either underutilized to produce low market value products or dumped leading to environmental issues. Complete utilization of fishery wastes for recovering value added products would be beneficial to the society and individual. The fish protein hydrolysates and derived peptides of fishery resources are widely used as nutritional supplements, functional ingredients, and flavor enhancers in food, beverage and pharmaceutical industries. Antioxidants from fishery resources have attracted the attention of researchers as they are cheaper in cost, easy to derive, and do not have side effects. Thus the present investigation was designed to produce protein hydrolysate by pepsin and papain digestion from the backbones of Rastrelliger kanagurta (Indian mackerel) and evaluate its antioxidant properties through various in vitro assays. The results reveal that both hydrolysates are potent antioxidants, capable of scavenging 46% and 36% of DPPH (1,1-diphenyl-2 picrylhydrazyl) and 58.5% and 37.54% of superoxide radicals respectively. The hydrolysates exhibit significant (p < 0.05) reducing power and lipid peroxidation inhibition. Among the two hydrolysates produced, pepsin derived fraction is superior than papain derived fraction in terms of yield, DH (Degree of hydrolysis), and antioxidant activity.