牦牛肉宰后成熟嫩化与细胞凋亡酶活力变化研究

Tenderness and Apoptotic Activity of Yak Meat during Postmortem Aging

为研究宰后牦牛肉成熟过程中前驱肱三头肌（TB）、中部背最长肌（ML）、后驱半膜肌（SM）的剪切力、肌原小片化指数及细胞凋亡酶（caspase）的变化趋势，选取24头甘南黑牦牛进行屠宰，于0～4℃、风速0．5m／s条件下成熟，在宰后成熟过程中的不同时间点（0．5h、2h、5h、10h、1d、2d、3d、4d、5d、6d、7d）进行剪切力、肌原纤维小片化指数和caspase-3、caspase-8、caspase-9活力测定。宰后7d，TB、ML和SM3个不同部位肉的剪切力值分别下降了35．6％、27．4％、33．5％；肌原小片化指数值分别升高了69．7％、65．7％、63．0％。TB和SM在宰后1dcaspase一3活力达到最高值（P〈0．001），ML则在宰后10h后达到活力最高值。TB和ML在宰后5h达到caspase-8活力最高值（P〈0．001），比ML提前达到caspases-8活力最高值。宰后5h后caspase一9活力显著高于宰后0．5h（P〈0．001），且ML和SM的caspase一9活力达到最高值，而TB的caspase一9在宰后10h后达到最高值，是其初始值的2．39倍；3个不同部位肉的caspase一3与caspase．8活力分别与剪切力和肌原小片化指数呈显著相关性（P〈0．01），caspase-3活力与caspase一8和caspase．9活力相互之间都呈显著相关性（P〈0．05）。结果表明：宰后成熟过程使牦牛肉的剪切力降低、肌原小片化指数提高，率先激发caspase_8、caspase-9活力，同时活化了caspase-3，破坏肌原纤维结构，降解细胞骨架蛋白，从而提高牦牛肉的嫩度。

Totally 24 Gannan yak were slaughtered at 0 - 4℃, wind speed 0.5 m/s conditions to aging , then the shear force, MFI and apoptotic enzymes activity were determined during postmortem aging. Results from this research show that the shear force values of TB, ML and SM decrease by 35.6% , 27.4% , 33.5% , and the MFI values increase by 69.7% , 65.7 % , 63.0%. This investigation also indicated that TB and SM at l d postmortem aging caspase-3 activity reach the highest value （P 〈 O. 001）, while ML at 10 h postmortem aging caspase-3 activity reaches the highest value; caspase-8 activity reaches the highest value activity （P 〈 0. 001 ） at 5 h postmortem aging, and the caspase-8 activity of TB and SM reach highest value earlier than ML; at 5 h postmortem aging, caspase-9 activity is significantly higher than that at 0.5 h postmortem aging（P 〈 0. 001 ） , at the same time caspase-9 activity reaches the highest value in ML and SM muscles, while the caspase-9 activity of TB reaches the highest value at 10 h postmortem aging, it is 2.39 times than its initial value; the caspase-3 and caspase-8 activity is related to shear force and MFI significantly （P 〈 0.01 ） , while caspase-3, caspase-8 and caspase-9 activity show significant correlation with each other （P 〈 0.05）.