Effects of different slaughtering methods on the energy metabolism, apoptosis process and quality of grouper (Epinephelus fuscoguttatus) during cold storage at 4 °C

BACKGROUND The aquatic processing industry is increasingly aware of the need to ensure that slaughtering is carried out under high welfare standards, so there is a need to explore the impact of slaughter methods on fish fillets. This study aimed to investigate the effects of different slaughtering methods (M 1 , lethality by hammering; M 2 , gas mixture causing death; M 3 , lethality by clove oil anesthesia + ice slurry; M 4 , lethality by ice slurry; M 5 , lethality by gradient cooling) on the energy metabolism, apoptosis and flesh mass in grouper ( Epinephelus fuscoguttatus ). RESULTS Therefore, 120 fish (24 per treatment) were slaughtered by the five methods. The results showed that the succinate dehydrogenase (SDH) enzyme activity of M 5 sample was higher. The serum glucose level of M 2 samples and DAPI staining fluorescence of M 2 samples were the highest, indicating that the stress response of M 2 was strong. In addition, the texture, pH, total volatile basic nitrogen (TVB‐N), thiobarbituric acid (TBA) and K value results showed M 5 samples had better flesh quality. CONCLUSION Gradient cooling lethality had the least effect on oxidative damage and apoptosis in grouper during cold storage as the gradient cooling lethality had the least effect on antioxidant enzyme activities.