Effect of different stunning methods on antioxidant status, myofibrillar protein oxidation, and gelation properties of large yellow croaker during postmortem

Post-mortem muscle biochemical processes play a crucial role on fish fillets quality and they are strictly linked to stunning methods. The improper stunning methods before slaughter could cause the fish to deteriorate more quickly during cold storage. This study aimed to investigate the effect of stunning methods (hit on the head, T(1); gill cut, T(2); immersion in ice/water slurry, T(3); CO(2) narcosis, T(4); 40% CO(2) + 30 % N(2) + 30% O(2), T(5)) on myofibrillar proteins (MPs) of large yellow croaker. The results indicated that T(2) and T(3) samples were significantly damaged compared with other samples, which reflected that the activities of total superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were significantly damaged during cold storage in T(2) and T(3) samples. And the gill cut and immersion in ice/water slurry resulted in the generation of protein carbonyl, the decrease of Ca(2+)-ATPase, free ammonia and protein solubility, and the production of dityrosine during storage. In addition, MPs gel of T(2) and T(3) samples showed the decrease of water hold capacity (WHC) and whiteness, structure destruction, and water migration. The T(4) samples had the least damage of MPs and gel structure during cold storage.