Effects of the Aging Time after Slaughter on Changes in the Intracellular Environment of Different Parts of Yak Meat
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Abstract:
The relationship between intracellular changes in the muscle cells and meat tenderness in different yak parts during different periods of the postmortem aging process was explored. Yak meat was treated with air cooling (0~4 ℃, air speed 0.5 m/s), and the front triceps brachii muscle (TB), central longissimus muscle (ML), and rear semimembranosus muscle (SM) were taken between two hours and five days after slaughter. The pH value, extracellular space area of muscle cells, mitochondrial morphological changes, and activity of the energy factor were measured. Moreover, Ac-DEVD-CHO, a specific inhibitor of caspase-3, was added to perform sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) protein electrophoresis. The results suggested that within 12 h to 24 h postmortem, a significant reduction in the pH of ML (pH=5.17±0.4, p<0.01) was detected. At 24 h postmortem, the extracellular space area of SM was significantly increased by 48.75% (p<0.05) compared with that of the sample at 12 h postmortem. At five days postmortem, significant mitochondrial fusion occurred in ML, and some mitochondrial crests remained in TB. At three days postmortem, the adenosine triphosphate (ATP) content of ML was significantly decreased by 79% compared to the samples at 24 h postmortem, and almost fell to the lowest level (p<0.01). At 12 h postmortem, the protein degradation in TB and ML was significantly inhibited by the caspase-3 specific inhibitor, and an apparent 30 ku protein band was detected in ML. The result showed that the aging process postmortem, the environmental changes in the muscle cells of different parts of yak, and the changes in the quality of yak meat are synchronized.
