Abstract: 【Objective】The conversion from muscle to meat after slaughter includes rigor, aging and a series of complicated changes. Temperature is very important for this process and the quality of meat. Aging process also affects meat quality. The objective of this study was to investigate the process of glycolysis in controlled freezing point storage and provide theoretical basis for regulating the speed of aging. 【Method】The longissimus of Poll Dorset rams were stored at controlled freezing point (-1--2℃) and refrigeration (2-4℃) for 9 days. The products of glycolysis and glycolytic activity of key enzyme were analyzed by the corresponding kit. The degradation of myofibrillar protein during post-mortem were analyzed by myofibrillar fragmentation index, combining with the activity of calpain which were analyzed by casein enzyme analysis. 【Result】 The pH value of the refrigeration and controlled freezing point groups were decreased to the minimum value at 3 d and 7 d, respectively, and then increased gradually. The difference of the minimum value of the two groups were not significant. The content of glycogen decreased and then had no significant changes. There were no significant difference between the two groups during post-mortem. The contents of lactic acid were increased and then became stable, followed by degradation, and the lactic acid content of refrigeration was significantly higher than controlled freezing point at 2 h, 6 h, 12 h, 24 h post-mortem. Pyruvate kinase activity reduced before they were stable, and the pyruvate kinase activity of controlled freezing point was significantly higher than refrigeration at 2 h, 24 h post-mortem. Lactate dehydrogenase activity was first increased and then decreased before becoming stable. The lactate dehydrogenase activity of samples in refrigeration was significantly higher than in controlled freezing point storage at 6 h, 12 h, 24 h, 5 d post-mortem. The activity of μ-calpain was increased first and then decreased, μ-calpain activity of controlled freezing point was significantly higher than refrigeration at 12 h, 24 h, 5 d, 7 d post-mortem. Myofibrillar fragmentation index increased gradually, and myofibrillar fragmentation index of refrigeration was significantly higher than controlled freezing point at 6 h, 12 h, 3 d, 5 d, 7 d, 9 d post-mortem.【Conclusion】Compared with refrigeration, there was no significant difference in glycolysis content and minimum pH value between the two groups, but the controlled freezing point delayed the glycogen degradation about 2 d and the lactic acid accumulation about 1 d. Controlled freezing point could impact the decrease of pyruvate kinase activity and the increase of lactic dehydrogenase activity. In addition, controlled freezing point could also weaken the inactivation of μ-calpain. Controlled freeing point could delay glycolysis process about 1-2 days, so it can delay the aging of muscle.

Key words: muscle, controlled freezing point, aging, calpain