Evaluation of the Common carp (Cyprinus carpio) fillet shelflife incorporated with fish protein hydrolysate

Fish Fillets are perishable due to their poly unsaturated fatty acids and the use of natural antioxidants during storage is of interest to researchers. The aim of this study was to investigate the effect of hydrolyzed protein produced from the viscera of common carp on the shelf life and quality of carp fillets at refrigerator (4±1°C). For this purpose, the common carp viscera were hydrolyzed with alkalase enzyme (concentration 1%, temperature 55 ° C and pH 8) during different times of 30, 60, 120 and 180 minutes and IC50 of hydrolyzed protein (after 180 minutes of hydrolysis) in the DPPH inhibition was obtained 1.34 ± 0.01 mg/ml and the IC50 of vitamin C was determined to be 13.78±0.6 μg/ml. Then, to investigate the effect of hydrolyzed protein on the shelf life of fillets, experimental treatments including fillets with hydrolyzed protein coating, fillets with vitamin C coating and control (without coating) were prepared, and then, chemical parameters (pH, TBA and TVB-N) and microbial (TVC and PTC) parameters were measured in carp fillets kept at 4±1 °C on days 0, 4, 8, 12, 16 and 20. During the storage period, TBA, TVB-N, TVC and PTC had an increasing trend in all treatments, but the level of these indices in the control treatment was significantly higher than those treated by hydrolyzed protein and vitamin C (p<0.05). Overall, comparison of hydrolyzed protein and vitamin C showed that in all studied indices (except TVB-N on some days of storage), the function of hydrolyzed protein in IC50 was similar to vitamin C and can be suggested as an antioxidant to increase shelflife of fish fillet at refrigerator.