Laboratory of Fishery Nutritional Science, Faculty of Fisheries, Nagasaki University, Nagasaki, Nagasaki 852-8521, Japan
Fragmentation of myofibrils at various storage temperatures (0, 15, and 30°C) was studied using carp acclimated to 10°C (group L) and 30°C (group H). Fragmentation of myofibrils tended to proceed faster in group H than in group L at all storage temperatures. We examined some of the factors which might influence this difference in fragmentation of myofibrils between groups L and H. The increasing rate in extent of contraction of muscle was higher in group H than in group L at 0°C, hardly differed between groups L and H at 15°C, and was much lower in group H than in group L at 30°C. Calpain activity of group H was higher than that of group L at reaction temperatures of 25°C and 30°C, whereas the activity of group H was slightly lower than that of group L from 0°C to 20°C. Sarcoplasmic reticulum Ca-ATPase activities were higher in group L than in group H at almost all the reaction temperatures from 0°C to 30°C. Consequently, it was suggested that the difference in the fragmentation rate of myofibrils between groups L and H might be caused by these factors.