Abstract: The aim of the study was to investigate the effects of high oxygen modified atmosphere packaging on the quality of beef semimembranosus muscle during postmortem aging. Four Simmental cattle were slaughtered and semimembranosus muscles from each carcass were excised, packaged in high oxygen modified atmosphere (80% O2 + 20% CO2) or in vacuum at 24 h postmortem and then stored at 4 ℃. Meat tenderness, color, protein solubility, thiobarbituric acid reactive substances (TBARS) value, and the proteolysis of troponin-T were determined after 0, 4, 7 and 10 days of storage. The distribution of protein carbonyl groups in muscle cells was observed by confocal laser scanning microscopy. The results showed that meat tenderness, the solubility of sarcoplasmic protein on day 7 of storage and total protein solubility in high oxygen modified atmosphere packaged samples were significantly lower than those of vacuum packaged samples (P < 0.05), while TBARS value was significantly higher (P < 0.05) and the fluorescence signal of protein carbonyl groups was similarly higher in the former, which penetrated?from the exterior to the interior of?the cells with increasing storage time. Moreover, the rate of proteolysis of troponin-T significantly decreased compared with the vacuum packaging group (P < 0.05). However, high oxygen modified atmosphere packaging maintained higher surface redness values (P < 0.05) in comparison with vacuum packaging during the 10-day storage period. In conclusion, high oxygen modified atmosphere packaging increased the level of lipid and protein oxidation, thereby inhibiting μ-calpain degrading of troponin-T and finally decreasing the tenderness of beef samples.

Key words: high oxygen modified atmosphere packaging; beef; quality; oxidation; proteolysis