The effects of modified atmosphere packaging and enzyme inhibitors on protein oxidation of tilapia muscle during iced storage

•Protein oxidation indices in tilapia muscle samples increased with iced storage.•Modified, oxygen-free atmosphere packaging attenuated protein oxidation.•Inhibitors of endogenous proteases attenuated protein oxidation.•Best preservation was achieved by modified packaging or by inclusion of MDL-28170.

The objectives of this study were to investigate whether modified atmosphere packaging (MAP) and inhibitors of calpain, caspase-3, and cathepsins can reduce protein oxidation of tilapia muscle during iced storage. Parameters such as protein solubility, total carbonyl and sulfhydryl content as well as electrophoretic pattern of myofibrillar proteins from tilapia muscle were examined. We found that protein solubility, sulfhydryl group contents, and electrophoretic band intensities of myosin heavy chain and actin in MAP samples were significantly higher, whereas carbonyl content was significant lower than those in AP samples (P < 0.05). The extent of degradation in myosin heavy chain and actin in muscle tissue stored in AP was higher than that in MAP, suggesting that the latter was a better method to reduce protein oxidation during iced storage. After storage for 14 d with different enzyme inhibitors, carbonyl content, sulfhydryl content, and protein solubility in muscle samples were significantly affected by treatment (P < 0.05 for all three measures). The best preservation effect, similar to that of MAP, was achieved by the inclusion of the calpain inhibitor MDL-28170.