Production and purification of antioxidant peptides from flatfish skin protein hydrolysates

Antioxidant peptides of flatfish skin protein hydrolyzed by four enzymes(Papain, Pepsin, Trypsin and Neutrase, respectively)were investigated. The Trypsin hydrolysate obtained by hydrolysis exhibited the highest 1,1-dipheny-l-2-picrylhydrazyl(DPPH)radical scavenging activity(DRSA)compared with other hydrolysates. Response surface method ology(RSM), based on Box-Behnken design, was used to study the influence of hydrolysis conditions on the DRSA. The optimal hydrolysis conditions were as follows: pH 7.38, temperature 48.2°C and enzyme/substrate(E/S)ratio 2 840 U/g. Under these conditions, the maximum DRSA was(22.85 ± 0.57)%,. The experimental values agreed with the value (23.09%,)predicted by the model within a 95%, confidence interval. By using gel filtration chromatography and reversed-phase high performance liquid chromatography(RP-HPLC), antioxidant peptide(D2-P)was isolated from flatfish skin protein hydrolysates(FSPH)and could exhibit a(54.28 ± 1.37)%, scavenging activity on DPPH radical at the concentration of 5 mg/mL. This is the first report of a scientific basis for the preparation of antioxidant peptides from flatfish skin. The results suggested that the antioxidant peptides can be exploited into functional foods or used as a novel source of nutraceuticals.