Effects Of Recombinant UK114 Protein On Meat Tenderness And Water Holding Capacity Of Shanxi Black Pigs

Shanxi black pig,as a kind of local hybrid pig,has been widely recognized by the insiders because of its strong adaptability,rough feeding tolerance,stable genetic performance,strong ability to give birth,delicious meat quality and so on.The main indexes of meat quality evaluation include: pH value,meat color,flavor,tenderness and and water-holding capacity etc.,And calpain is the key endogenous enzyme affecting the tenderness and water-holding capacity of post-slaughtered pork,and UK114 is one of the main activating proteins of ?-calpain.Therefore,in this experiment,Shanxi black pigs were taken as the research object,and 10% meat weight UK114 protein,calpastatin and calpain crude enzyme solution were injected into the longissimus dorsi muscle of postmortem pigs.After the treatment groups were stored at4? for different time,the pH value,apparent water holding capacity and water content of the muscles were measured respectively;Myofibrin was extracted,its hydration characteristics were determined,and protein degradation was analyzed by SDS-PAGE.And to explore the effects of recombinant UK114 protein and calpastatin on calpain activity and meat quality characteristics of Shanxi black pigs during postmortem meat ripening mediated by ?-calpain.The test results show that:The pH value of muscles in each group decreased first and then increased,but the overall change was not significant(P<0.05),except the calpastatin group,the lowest pH value of other groups were higher than that of the control group.The water loss rate under pressure of the UK114 and calpain groups reached the peak at 12 h,and the UK114+calpain group reached the peak at 6 h,significantly earlier than the control group.And the overall storage loss showed a decreasing trend.The UK114 group and calpain group were significantly lower than the control group at 48 h(P<0.05);After 24 h,the content of P22 in UK114 group and calpain group was higher than that of the control group.It could be seen that the addition of UK114 and calpain reduced the juice loss of muscle in the early stage of muscle destiffnes and maturation,and the muscle water-holding capacity was improved.The protein surface hydrophobicity UK114 group and the calpain group reached the peak at 12 hours,while UK114+calpain group reached the maximum value at 6 h.And the solubility of UK114+calpain group reached the minimum value of 103.38 at 6 h.Indicating that calpain,UK114 and calpain can affect the protein hydration characteristics.The myofibril fragmentation index of UK114+calpain treatment group was significantly higher than that of the control group,and the shear force was significantly lower than that of the control group after 24 hours,and the protein bands was degraded significantly at 12 to 48 hours.To sum up,injecting appropriate amount of UK114 protein and calpain crude enzyme solution into pigs after slaughter can accelerate the degradation of myofibrillar protein,accelerate the release of muscle rigidity,reduce the loss of juice during muscle stiffness,promote the maturity of postmortem muscle,and improve the tenderness and water holding capacity of pork at the initial stage of slaughter.