不同部位冷却牛肉成熟过程中水分变化研究

为探究宰后不同部位牛肉在成熟过程中的水分变化及其产生原因，以成熟1、2、3、5、7d的冷却牛背最长肌、半膜肌和腰大肌作为研究对象，通过测定贮藏损失率、弛豫峰面积和比例、肌节长度和肌纤维直径，从贮藏损失、横向弛豫特性和肌肉结构特性3方面阐述了3种部位冷却牛肉在成熟过程中保水性、水分分布及细胞组织学的变化。结果表明，在成熟过程中，3种部位冷却牛肉的贮藏损失均呈现显著升高的趋势，腰大肌的保水性显著高于背最长肌和半膜肌（P<0.05）；3种部位牛肉的各弛豫峰面积均显著降低（P<0.05），且各部位的结合水比例和不易流动水比例间的差异性不大（P>0.05）；半膜肌的肌细胞排列松散，且肌节长度短，腰大肌具有较长的肌节和较小的肌纤维直径。不同部位肌细胞结构的差异导致不同部位牛肉呈现出不同的保水性。

Water Changes in Different Parts of Chilled Beef during Postmortem Aging

Water-holding capacity (WHC) refers to the ability of meat to retain moisture when force is applied. As an important processing quality, WHC of beef affects the quality of the final products. The quality of different parts of beef have significant differences. Different WHC not only has an important impact on the flavor, tenderness and juiciness of different parts of beef, but also has an important economic significance. It is helpful to take corresponding measures to control the loss of water by clarifying the WHC of different parts of chilled beef during aging time. Thus, in order to investigate the changes of water distribution during postmortem ageing, the chilled M. longissimus lumborum (LL), M. semimembranosus (SM) and M. psoas major (PM) beef aged for 1d, 2d, 3d, 5d and 7d were investigated. From the perspectives of purge loss, low field nuclear magnetic resonance (LF-NMR) characteristics and muscle structure, the changes of WHC, water distribution and microstructure of the three parts of chilled beef were described. The results indicated that the purge loss of three parts of chilled beef was increased significantly during postmortem aging time. And the WHC of PM were significantly higher than that of LL and SM (P<0.05). The area of relaxation peak (A2) in three parts of beef was decreased significantly (P<0.05) and the differences among P2b and P21 were not significant (P>0.05). The loose arrangement of myofiber and the short length of sarcomere resulted in the poor WHC of SM. PM had longer sarcomere and smaller myofiber diameter. The difference of myofiber structure in three parts of beef resulted in different WHC.