Relationship Among Changes of μ-calpain, pH and Skeleton Protein and Water Holding Capacity of Post-mortem Pork

To investigate the relationship between pH, μ-calpain, desmin and integrin changes and water holding capacity in postmortem pork, 20 samples of longissimus dorsi with different drip loss were divided into High drip loss group(H-group drip loss≥5.01%, n = 10) and Low drip loss group (L-group drip loss≤4.00%, n = 10). pH, μ-calpain activity and expression levels of desmin and integrin were determined in 45 min, 3, 9, 12 and 24 h after slaughter. The results showed that the drip loss of H-group was significantly higher than L-group (P<0.01), desmin expression level (3～24 h) was higher than that of L group (P<0.05), the activity of μ-calpain (12 h and 24 h) was lower than that of L group (P<0.05), integrin expression level (45 min, 3 h and 12 h) and pH (45 min～12 h) was lower than that of L group. The expression of desmin was positively correlated with the drip loss, while the expression of integrin, the activity of μ-calpain and pH were negatively correlated with the driploss.pH, the express level of μ-calpain autolysis, desmin and integrin explained 78.1%, 42.4%, 70.3% and 71.7% of the variation in drip loss, respectively .The results showed that pH, μ-calpain, desmin and integrin all had an effect on drip loss, pH is the single variable that has the greatest influence on drip loss.