高氧气调包装对宰后猪肉蛋白质氧化、钙蛋白酶活性及蛋白质降解的影响

【目的】研究高氧气调包装（HiOx，80% O₂/20% CO₂）对宰后猪肉蛋白质氧化、钙蛋白酶活性及蛋白质降解的影响，探讨高氧气调包装影响猪肉品质的内在机制。【方法】选取12条冷却（4℃）24 h后的杜洛克×长白×约克夏三元杂交猪背最长肌，分别进行高氧气调包装和真空包装（VP），4℃冷库贮藏，分别在1、4、6 d测定羰基含量及分布、巯基含量、肌节变化、钙蛋白酶活性、肌联蛋白及肌钙蛋白-T降解变化。【结果】高氧气调包装组羰基含量高于真空包装组且贮藏第4和6天差异显著（P＜0.05）。贮藏第1和4天，高氧气调包装组肌细胞外围出现羰基氧化荧光信号，荧光以靠近细胞膜处密度更高，并且逐渐向细胞内部扩散；贮藏第6天，高氧气调包装组细胞膜呈高亮荧光圈，胞内荧光增强，而真空包装组荧光信号较弱。贮藏第6天，高氧气调包装组巯基含量显著低于真空包装组（P＜0.05）。真空包装组宰后肌节M线弱化、A带模糊、肌原纤维Z线断裂；高氧气调包装组肌节结构相对完整。高氧气调包装组在贮藏第1天钙蛋白酶活性显著低于真空包装组（P＜0.05）；高氧气调包装抑制了肌联蛋白和肌钙蛋白-T的降解，且在贮藏第4和6天差异显著（P＜0.05）。【结论】高氧气调包装能够显著提高宰后猪肉蛋白质氧化程度，抑制钙蛋白酶活性发挥及其底物蛋白质的降解。

Effects of High Oxygen Modified Atmosphere Packaging on Protein Oxidation,Calpain Activity and Protein Proteolysis of Pork During Postmortem Refrigerated Storage

【Objective】 The objective of this study was to investigate the effect of high oxygen modified atmosphere packaging (HiOx, 80% O₂/20% CO₂）on protein oxidation, calpain activity and protein proteolysis of pork during refrigerated storage. This could help explaining the mechanism of regulation behind HiOx in pork quality. 【Method】 Twelve longissimus dorsimuscles of Duroc × Landrace × Yorkshire crossbred pork were precooled at 4℃ for 24 h, and then randomly assigned to either HiOx or vacuum packaging (VP) and stored for 1, 4 and 6 d at 4℃. The carbonyl content and distribution, sulfhydryl content, sarcomere changes, calpain activity, titin and troponin-T degradation were determined, respectively. 【Result】 Carbonyl content of samples from HiOx was significantly higher than the samples from VP at 4 and 6 d of storage (P＜0.05). HiOx samples showed fluorescence signal in the peripheral area of cell membrane and then the fluorescence signal spread to the internal cellular environment at 1 and 4 d of postmortem refrigerated storage. At 6 d of postmortem refrigerated storage, samples under HiOx presented a strong fluorescence light, with a glaring fluorescence intensity more pronounced in a peripheral area corresponding to the cell membrane and to a region in close contact with the cell membrane, while VP samples presented weaker fluorescence signal. Sulfhydryl content of HiOx samples was significantly lower compared with VP samples at 6 d of postmortem storage (P＜0.05). Samples from VP showed weakening M line, blurry A band as well as broken Z line during postmortem refrigerated storage, whereas samples under HiOx remained less affected. μ-Calpain activity was less in samples from HiOx compared with that from VP at 1 d of storage (P＜0.05). Titin and troponin-T showed less proteolysis in samples from HiOx than that from VP at 4 and 6 d of postmortem refrigerated storage (P＜0.05). 【Conclusion】 Increased protein oxidation under HiOx could inhibit μ-calpain activity and protein proteolysis of pork during postmortem refrigerated storage.