Post-mortem changes in contents of glycolytic intermediates in the adductor muscle of noble scallop during storage

The changes of glycogen, glucose and several other glycolytic intermediates as well as muscle pH were examined in the adductor muscle of noble scallop during storage at 0 degrees C and 5 degrees C. Phosphorylase, hexokinase (HK), and phosphofructokinase (PFK) activities were also examined in relation to pH and temperature. Glycogen content immediately after death was 3.6 g/100 g and dropped rapidly during early storage. The initial contents of glucose and other glycolytic intermediates were low. Glucose and frucotose-6-phosphate accumulated to a lesser extent compared with glucose-6-phosphate. Glucose-1-phosphate, fructose-1,6-bisphosphate, and alpha-glycerol phosphate increased during strage, then decreased as the storage progressed. On the other hand, phosphoenolpyruvate and pyruvate increased continuously. The initial lactic acid content was 0.82 mu mol/g, consisting of 85% L-Lac. There were no substantial concentration changes of L-Lac during storage. On the other hand, D-Lac increased and reached 3.2 mu mol/g. The initial pH value was 6.88 and dropped faster at 5 degrees C than at 0 degrees C. Phosphorylase and PFK activities decreased as the incubation pH decreased, forming a sigmoid flexure. On the other hand, HK activity increased markedly as the pH dropped lower than 6.2. When the incubation temperature was lowered, PFK activity decreased faster than HK and phosphorylase activities.