Abstract: Pork Longissimus dorsi was oxidized using a hydroxyl radical oxidation system (FeCl3-VC-H2O2) to investigate the effect of oxidative stress on the water-holding capacity (WHC) of pork. The results showed that there were no significant changes in centrifugal loss rate, carbonyl content, endogenous fluorescence chromatography and calcium-transporting ATPase expression measured when the concentration of H2O2 was less than 1 mmol/L. As the concentration of H2O2 increased further, especially when exceeding 10 mmol/L, the indicators began to show obvious differences. The degrees of cross-linking and degradation of proteins increased significantly as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and a significant increase in the gap between muscle fiber bundles was observed by scanning electron microscopy (SEM). When the H2O2 concentration was larger than 10 mmol/L, the expression of calcium-transporting ATPase reached its maximum, and the expression of cathepsin L was greatly reduced and reached its minimum at 20 mmol/L. Also, high concentration of H2O2 (> 10 mmol/L) caused a significant change in the expression of endogenous enzymes in pork Longissimus dorsi, significantly increased the degree of oxidative degradation of pork protein, which affected the microstructure of pork meat and reduced in WHC.

Key words: hydroxyl radical; pork meat; oxidative stress; endogenous enzyme; water-holding capacity