1Nagasaki Prefectural Institute of Fisheries, Taira, Nagasaki 851-2213, Japan, 2Laboratory of Fishery Nutritional Science, Graduate School of Science and Technology, Nagasaki University, Bunkyo, Nagasaki 852-8521, Japan
In order to evaluate the effect of different killing methods (instant, struggled, temperature shock and spinal cord destruction) and storage temperatures (iced, 5, 10, 15, 20°C) on postmortem changes in the muscle of the cultured three-line grunt, the adenosine triphosphate (ATP), inosine monophosphate (IMP) concentrations, K-value and rigor index were investigated. A primary study on killing procedures showed that the spinal cord destruction method was the best, since the ATP concentrations resulted in a slow decrease and IMP concentrations, K values and rigor index showed slow increases respectively. For the storage temperature study, two fish groups with different culture temperatures, winter and summer, were used. When the changes in ATP, IMP, K-values and rigor index were compared, fish cultured at winter temperatures had relatively slower variations than those cultured at summer temperatures. Regarding the storage temperature tests, the 10°C storage resulted in slower increases in K-values and rigor index. From these results, it can be concluded that the spinal cord destruction method and storage at 10°C, regardless of culture temperature, were the most effective in delaying post-mortem changes of the three-line grunt even 24 h after postmortem.