Stability of papain-treated grass carp (Ctenopharyngodon idellus) protein hydrolysate during food processing and its ability to inhibit lipid oxidation in frozen fish mince

Impact of food processing on the antioxidant activities of grass carp protein hydrolysate (GPH) and the ability of GPH to inhibit lipid oxidation in fish mince during frozen storage (−10 °C) were studied. The metal chelating activity and reducing power of GPH were stable in a temperature range from 40 °C to 100 °C and in a pH range from 3 to 9. GPH could still scavenge 63.8 % 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and chelate 70.5 % ferrousion in the presence of glucose, sucrose or NaCl. At the application of 2.0 %, it was found that the peroxide values, the formation of conjugate dienes and thiobarbituric acid reactive substances of GPH decreased to 51.1 %, 49.7 % and 34.5 %, respectively, at week 5 of storage compared to control. The results revealed that the antioxidant activities of GPH were stable during food processing and could be used as a natural antioxidant in muscle food.