An investigation on antioxidative properties of different molecular weight fractions of protein hydrolysate produced from Common carp (Cyprinus carpio) head

In the present study, the antioxidant properties of different molecular weight fractions and different concentrations of protein hydrolysate from Common carp (Cyprinus carpio) head were investigated. Fish heads were hydrolyzed by Alcalase enzyme (1% v/w) at 55˚C and pH 8 during 180 min. The supernatant was fractionated to three different molecular weight fractions of <3, between 3 and 10 and >10 KDa by ultrafiltration. The results showed a significant difference between DPPH radical scavenging activity of the different molecular weight fractions, and the highest and the lowest values ​​were observed in the fractions of 3-10 and less than 3 KDa, respectively (p <0.05). The fraction with molecular weight of 3-10 KDa showed the lowest IC50 (1.15±0.015 mg/ml) for DPPH scavenging activity.  As the concentration increased, ferric ion reducing power of all molecular weight fractions were increased, and the highest value was observed in the molecular weight of more than 10 kDa (p <0.05). Significant differences of ABTS radical scavenging activity were observed between the different molecular weight fractions at all concentrations, and the highest and the lowest values ​​were observed in the molecular weight fractions of 3-10 and less than 3 kDa, respectively (p <0.05). The molecular weight fraction of 3-10 kDa, exhibited the lowest IC50 value for ABTS radical scavenging activity (1.1±0.01 mg/ml). In general, according to the positive function of Common carp head protein hydrolysate at different concentrations and different molecular weights on DPPH and ABTS radical scavenging activity and ferric ion reducing power, it can be stated that this protein hydrolysate can be considered as a natural antioxidant for use in the food industry or animal, poultry and aquatic feed.