Chen Lijuan, Li Xin, Ni Na, Liu Yue, Chen Li, Wang Zhenyu, Shen Qingwu W, Zhang Dequan
Institute of Agro-Products Processing Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Products Processing, Ministry of Agriculture, Beijing 100193, People's Republic of China.
Synergetic Innovation Center of Food Safety and Nutrition, Beijing 100193, People's Republic of China.
J Sci Food Agric. 2016 Mar 30;96(5):1474-83. doi: 10.1002/jsfa.7244. Epub 2015 Jun 15.
Tenderness is one of the most important quality attributes especially for beef and lamb. As protein phosphorylation and dephosphorylation regulate glycolysis, muscle contraction and turnover of proteins within living cells, it may contribute to the conversion of muscle to meat. The changes of myofibrillar protein phosphorylation in post-mortem ovine muscle with different levels of tenderness were investigated in this study.
The protein phosphorylation level (P/T ratio) of the tender group increased from 0.5 to 12 h post mortem and then decreased. The P/T ratio of tough group increased during 24 h post mortem, increasing faster from 0.5 to 4 h post mortem than from 4 to 24 h post mortem.The global phosphorylation level of tough meat was significantly higher than tender meat at 4, 12 and 24 h post mortem (P < 0.05). Protein identification revealed that most of the phosphoproteins were proteins with sarcomeric function; the others were involved in glycometabolism, stress response, etc. The phosphorylation levels of myofibrillar proteins, e.g. myosin light chain 2 and actin, were significantly different among groups of different tenderness and at different post-mortem time points (P < 0.05).
Protein phosphorylation may influence meat rigor mortis through contractile machinery and glycolysis, which in turn affect meat tenderness.
嫩度是牛肉和羊肉等肉类最重要的品质属性之一。由于蛋白质磷酸化和去磷酸化调节糖酵解、肌肉收缩以及活细胞内蛋白质的周转，其可能有助于肌肉向肉的转化。本研究调查了不同嫩度的宰后绵羊肌肉中肌原纤维蛋白磷酸化的变化。
嫩度组的蛋白质磷酸化水平（P/T 比值）在宰后 0.5 至 12 小时升高，随后下降。硬度组的 P/T 比值在宰后 24 小时内升高，在宰后 0.5 至 4 小时的升高速度比 4 至 24 小时更快。在宰后 4、12 和 24 小时，硬肉的整体磷酸化水平显著高于嫩肉（P < 0.05）。蛋白质鉴定显示，大多数磷蛋白是具有肌节功能的蛋白质；其他的则参与糖代谢、应激反应等。不同嫩度组和不同宰后时间点的肌原纤维蛋白（如肌球蛋白轻链 2 和肌动蛋白）的磷酸化水平存在显著差异（P < 0.05）。
蛋白质磷酸化可能通过收缩机制和糖酵解影响肉的尸僵，进而影响肉的嫩度。
