Evaluation the antioxidant properties of purified bioactive peptides from the wastes of skipjack fish (Katsuwonus pelamis) processing, by pepsin and trypsin digestive enzymes

In fish processing industries, 50-70% of primary fish are produced as waste, while they are rich sources of protein and essential amino acids. The optimal use of these wastes and the production of compounds with high added value that have significant health-giving properties is one of the important challenges of fish processing industries. In this research, the effect of hydrolysis conditions (time: 30-300 minutes and enzyme concentration 0.5-3%) and type of protease (pepsin and trypsin) on the degree of hydrolysis and antioxidant properties (DPPH radical scavenging activity, Fe chelating activity, No radical scavenging activity, total antioxidant capacity and Fe reducing power) of hydrolyzed protein obtained from Skipjack viscera were evaluated using response surface methodology. The results showed that the optimal conditions for the production of hydrolyzed protein with the maximum antioxidant properties with pepsin and trypsin enzymes were respectively: hydrolysis time of 179.09 and 143.62 minutes and enzyme concentration of 2.63 and 1.94 %; In this condition, the degree of hydrolysis of the hydrolyzed proteins resulting from the activity of trypsin was calculated to be higher than that of pepsin. Comparing the antioxidant properties of the hydrolysates obtained from the two enzymes used showed that the hydrolyzed protein obtained from trypsin had a stronger antioxidant potential than pepsin. Therefore, it can be stated that the hydrolyzed protein of the Skipjack viscera using trypsin enzyme as a health-giving supplement and with high added value can be used in the production of functional food products and health supplements for athletes and elderly people.