Effect of Hypoxia-Inducible Factor 1 on the Contents of Energy Metabolites and Meat Color in the Early Aging Period of Tan Sheep Meat

This study was designed to clarify the changes in the expression level of hypoxia-inducible factor 1 (HIF-1) and its effects on the activity of triose-phosphate isomerase (TPI), the contents of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP), and meat quality traits in Tan sheep meat during a 48-hours postmortem aging period. Results indicated that the expression level of HIF-1 increased significantly between 2 and 24 h, and then decreased. The activity of TPI increased significantly, reaching a maximum value at 6 h, then significantly decreased until 48 h. The contents of ATP, ADP, and AMP significantly decreased with increasing aging time, while muscle pH significantly decreased (P < 0.05). The color values of L*, a*, and b* were significantly increased with increasing aging time. Correlation analysis indicated that the expression level of HIF-1 was correlated with meat quality indicators, TPI activity, and the contents of ATP, ADP and AMP significantly (P < 0.05, P < 0.01). It might be speculated that postmortem hypoxia could induce a rapid increase in the expression level of HIF-1 within 6 h postmortem, and the transfer of the HIF-1 complex to the nucleus to bind with glycolytic genes, thereby promoting the expression of glycolysis-related genes, enhancing postmortem glycolysis, leading to increased activity of glycolysis-related enzymes and decreased muscle pH. To sum up, HIF-1 can affect meat color by regulating postmortem muscle glycolysis and pH.