Effect of hydrolysis time on the antioxidant activity of Common carp (Cyprinus carpio) head protein hydrolysate

In the present study, the antioxidant activity of different concentrations of protein hydrolysate from Common carp (Cyprinus carpio) head at different hydrolysis time was investigated. For this purpose, 8 Common carp fish with average weight of 0.766±0.034 kg were prepared from market. Fish heads were hydrolyzed by Alcalase (1% v/w at 55˚C and pH 8) at different hydrolysis times (30, 60, 120 and 180 min). The result of proximate analysis showed that the protein content increased  significantly (from 58.31±1.9 to 75.26±1.49%) as a result of  hydrolysis, while the amount of fat and ash decreased significantly (from 16.46±0.87 to 2.37±0.97%; from 27.16±0.64 to 25.34±1.63%, respectively, p < 0.05). Also, as the duration of hydrolysis increased, the amount of soluble protein and the degree of hydrolysis increased significantly, so that the highest soluble protein 23.01±0.19 mg/ml and the highest degree of hydrolysis 49.67±0.86% were obtained at the time of 180 min. DPPH radical scavenging activity of protein hydrolysate showed significant increasing trend at different hydrolysis times and different concentrations (p < 0.05). The optimum time for DPPH radical scavenging activity (DPPH) was determined at 180 min and IC₅₀ value was obtained 2.08 mg/ml. In addition, with increasing concentration and duration of hydrolysis, the ferric ion reduction power and ABTS radical scavenging activity increased significantly (p < 0.05). In general, due to the proper activity of different concentrations of Common carp head protein hydrolysate on DPPH and ABTS radicals scavenging and reduction of ferric ion, it can be stated that this protein hydrolysate can be considered as a dietary supplement with desirable antioxidant function.