Effect Of Different Post-mortem Treatments On Yak Meat Quality

Yak is a unique breed of Tibetan Plateau. Yak meat has many advantages like nutritious, high protein, low fat, flesh red, etc. But, both palatability and tenderness of yak meat are poor. Therefore, how to improve the tenderness and palatability of yak meat become an urgent problem.There are many factors which can affect beef tenderness. Those factors can be summarized as ante-mortem and post-mortem factors. Ante-mortem factors include breed, age, sex, location, nutritional status, gene regulation, etc. Post-mortem factors include electrical stimulation, mechanical tenderization, hanging and stretching techniques, etc.Hot boning process has many advantages like costs saving and energy saving. But it would have a negative impact on meat quality. Electrical stimulation process can accelerate the rate of beef aging and improve the quality of beef. However, ES had almost no applications in yak manufacturer in China. The validity and mechanism are also in research. Wet-aging and dry-aging technology can improve the quality of beef effectively. Blade tenderization technology is also regard as one of the most effective tender techniques by many scholars. However, research on effect of aging methods and blade tenderization on quality of yak meat was less and was not enough systematic.The article studied effects of ultra low-voltage electrical stimulation, hot-boning, wet-aging, dry-aging, and blade tenderization on yak meat quality by water-holding capacity, shear force, meat color, myofibrillar ultrastructure and consumer preferences evaluation. Thus to provide theroretical foundation for post-mortem factors applications in yak meat production enterprises. Results showed:1. Hot-boning process reduced the WHC of yak sirloin and made the yak sirloin become tough. Hot-boning process had no significant effect on pH decline of yak sirloin in24h post-mortem(P>0.05) and also had no significant effect on meat color of yak sirloin at post-mortem(P>0.05). Ultra low-voltage electrical stimulation can accelerate pH decline rate of yak sirloin significantly at24h post-mortem(P<0.05). Ultra low-voltage electrical stimulation improved the tenderness and meat color of yak sirloin at post-mortem significantly(P<0.05). Meanwhile, ultra low-voltage electrical stimulation reduced the negative impact on the shear force of yak sirloin significantly(P<0.05). However, Ultra low-voltage electrical stimulation was not impact the WHC of yak sirloin significantly(P>0.05).2. Both Dry-aging and wet-aging improved the tenderness of yak sirloin significantly compared to the control group(P<0.05). The longer the aging time was, the more tender the yak sirloin would be. Dry-aging yak sirloin had higher water-holding capacity and aging loss and lower cooking loss when compared with wet-aging group. The Yak sirloin processed by dry-aging had no difference in pH value, meat color, shear force and consumer preferences evaluation results when compared with wet-aging group.3. Yak sirloin processed by different blade tenderizations were more tender when compared with control group. The more time processed by tenderizer, the more tender the yak sirloin would be. Blade tenderization reduced the water holding capacity of yak sirloin. But, blade tenderization did not significantly affect the pH value, meat color and cooking loss of yak sirloin(P>0.05). The consumer preferences eyaluation results of yak sirloin steak which processed by blade tenderization were much higher than control group.In the present study, all kinds of the different post-mortem treatments affected the quality of yak sirloin significantly. Therefore, post-mortem treatments should be used rationally in order to obtain high-quality yak meat. In terms of economic and practical, wet-aging21d combined with ultra low-voltage electrical stimulation for lmin and achilles stretch was the optimal treatment group.