本文研究了牦牛肉牛瘤胃肌原纤维蛋白特性及品质的变化规律，以期为平滑肌的深入研究提供理论参考。以牦牛肉牛瘤胃为研究对象，宰后4 ℃冷藏过程中测定其失水率、蒸煮损失、剪切力、肌原纤维小片化指数（MFI）、蛋白溶解度、表面疏水性及组织结构的变化规律。结果表明：整个冷藏过程中，两种瘤胃的失水率、蒸煮损失、MFI、表面疏水性呈上升趋势，均在7 d时上升到最大值。而剪切力、蛋白溶解度均呈下降趋势。牦牛瘤胃剪切力、总蛋白与肌原纤维蛋白溶解度分别在7 d时下降到最小值5.54 kgf、314.19 mg/g、116.37 mg/g。肉牛瘤胃剪切力在1 d时为最小值7.82 kgf；总蛋白与肌浆纤维蛋白溶解度在7 d时下降到最小值368.57 mg/g、221.75 mg/g；肌原纤维蛋白溶解度在5 d时为最小值139.21 mg/g。肌束膜和肌内膜排列散乱，肌纤维束间的空隙增大。综合分析：两种瘤胃品质变化规律的差异性，可能是肌纤维结构变化与蛋白溶解度的不同所造成的。

Law of change of the characteristic and quality of rumen myofibrillar proteins in yak and beef cattle were investigated in this study in order to provide a theoretical reference for the in-depth study of smooth muscles. Taking the rumen of yak beef cattle as the research object, the changes of water loss rate, cooking loss, shearing force, myofibril fragmentation index(MFI), protein solubility, surface hydrophobicity and microstructure were determined during refrigeration at 4 ℃.The results showed that, throughout the refrigeration process, the water loss rate, cooking loss, MFI and surface hydrophobicity of the two rumen showed an upward trend, which rose to the maximum on the 7th day. The shear force and protein solubility showed a downward trend. The rumen shear force, total protein solubility and myofibrillar protein solubility of yak decreased to a minimum of 5.54 kgf, 314.19 mg/g, and 116.37 mg/g, respectively, on the 7th day. The rumen shear force of beef cattle showed the minimum value of 7.82 kgf on the first day and the total protein solubility and sarcoplasmic fibrin solubility decreased to their minimum values of 368.57 mg/g and 221.75 mg/g, respectively, on the 7th day. The myofibrillar protein solubility decreased to a minimum of 139.21 mg/g on the 5th day. The fascia and endomysium showed a scattered arrangement with larger gaps between the muscle fiber bundles becomes. In conclusion, the difference in the regularity of the two rumen quality changes may be caused by the difference in muscle fiber structure and protein solubility.

甘肃省科技计划项目（18YF1NA075）；国家肉牛牦牛产业技术体系项目(CARS-37)