Abstract: 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.

Key words: Tan sheep; postmortem aging; hypoxia-inducible factor 1; glycolysis; energy substance; quality traits