宰后成熟时间对不同部位牦牛肉细胞内环境变化的影响

Effects of the Aging Time after Slaughter on Changes in the Intracellular Environment of Different Parts of Yak Meat

摘要:

研究不同部位牦牛肉宰后成熟过程中不同时段肌细胞内部变化与肉质嫩化的关系。将宰后牦牛肉冷却排酸（0~4 ℃，风速0.5 m/s），于宰后2 h~5 d取牦牛肉前部肱三头肌（TB）、中部背最长肌（ML）和后部半膜肌（SM）分析其pH值、肌细胞间隙面积、线粒体形态变化和能量因子活性，加入Caspase-3专一抑制剂Ac-DEVD-CHO制作SDS-PAGE全蛋白电泳图谱。宰后12 h~24 h，ML pH值显著下降pH=5.17±0.4（p<0.01）；宰后24 h，SM肌细胞间隙面积较12 h显著增大48.75%（p<0.05）；宰后5 d，ML线粒体溶融显著，TB线粒体嵴仍有一定存在量；宰后3 d，ML ATP含量变化较宰后24 h差异极显著下降79%，几乎降至最低点（p<0.01）；宰后12 h，Caspase-3专一抑制剂对TB和ML蛋白降解抑制显著，ML显著出现30 ku蛋白条带。结果说明，宰后成熟过程中不同部位牦牛肉肌细胞内环境变化与牦牛肉品质变化是同步进行的。

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.