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| Variations in Quality and Structural Characteristics of Yak Meat during Postmortem Aging |
| GUO Zhao-bin，HAN Lin，YU Qun-li |
| College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China |
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Abstract Shear force, pH, water loss rate, calpain activity, myofibril ultrastructure were measured on yak meat at days 1, 2, 3, 4, 5, 6, 7 and 8 after slaughtering to investigate variations in quality and structural characteristics of yak meat during postmortem aging. The initial pH of yak meat was 6.12 at 0-4 ℃, and decreased to its minimum level （extreme pH） 5.48 at day 4 after slaughtering, and the water loss rate reached its maximum level at the same day. The calpaln activity showed a gradual upward trend and a distinct increase at day 3 - 4. Notable variations in myofibril ultrastructure were found during postmortem aging, the M and H lines disappeared, and the Z line was seriously broken at day 5. These variations were consistent with those in the tenderness. Moreover, the highest shear force, 55.95 N, was found at day 4, and yak meat revealed the worst tenderness. The shear force began to decrease at day 5 and the tenderness reached the appropriate range for good palatability. Therefore, yak meat was completely aged.
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2012, Vol. 26 
