高氧气调包装下蛋白羰基化诱导肌原纤维蛋白交联对牛肉嫩度劣变的影响机制

High oxygen modified atmosphere packaging (HiOx-MAP) is becoming widely used for fresh beef, however it can affect meat tenderness negatively, in which cross-linking of myofibrillar protein (MFP) induced by protein carbonylation might play a significant role. To our best knowledge, no study has been done to link meat toughing with MFP cross-linking induced by protein carbonylation, and its underling mechanism is not yet clear. This study will focus on protein carbonylation and set vaccum packaging as control. Firstly, to find out the main pathway though which protein carbonylation occurs under HiOx-MAP and also the major carbonyled MFP, changes in the amounts of MFP carbonyls formed through different pathways during HiOx-MAP storage will be followed, and the carbonyled proteins will be recognized using western blotting. Secondly, to explain the association among cross-linking of MFP induced by protein carbonylation of beef under HiOx-MAP, myofibril structure and meat tenderness, the extent of cross-linking associated with protein carbonylation and specific cross-linking products will be quantified, and the changes in myofibril structure and meat tenderness will also be measured. Finally, to understand the effect of heating on MFP cross-linking in relation to protein carbonylation and further tenderness of beef under HiOx-MAP, beef steaks after stored in HiOx-MAP will be cooked, and then changes in protein carbonylation and its cross-linking will be studied. Collectively, the impact of this study is to provide theoretical guide for solving the toughing problem of meat in HiOx-MAP, and to help promote the healthy development in packing industry of fresh meat in China.

高氧气调包装越来越广泛应用于冷鲜牛肉，但易造成肉品嫩度的劣变，而蛋白羰基化诱导的肌原纤维蛋白交联可能是重要的原因，目前未见相关报道，机制尚不清楚。本课题拟以真空包装作为对照，首先研究高氧气调包装下经不同路径形成的肌原纤维蛋白羰基随贮藏时间的变化，借助免疫印迹分析发生羰基化的蛋白种类，明确高氧气调包装下蛋白羰基化的主要路径和蛋白质；然后，研究不同包装条件下肌原纤维蛋白羰基化交联总量和特征交联产物随贮藏时间的变化，观测肌原纤维结构和嫩度变化，阐明高氧气调包装贮藏中肌原纤维蛋白羰基化交联对肌原纤维结构和肉品嫩度的影响；最后，对经过贮藏的牛排加热，研究加热前后肌原纤维蛋白羰基化和羰基化交联的变化，明确加热是否会促进高氧气调包装肉中肌原纤维蛋白的羰基化交联进而加剧嫩度劣变。该项目将为解决高氧气调包装冷鲜肉嫩度劣变的问题提供理论指导，并有助于推动我国冷鲜肉包装行业的健康发展。

高氧气调包装越来越广泛应用于冷鲜牛肉，但易造成肉品嫩度的劣变，而蛋白羰基化诱导的肌原纤维蛋白交联可能是重要的原因，目前未见相关报道，机制尚不清楚。本课题首先研究了不同氧气浓度的气调包装下肉中肌浆蛋白质和肌原纤维蛋白总羰基、AAS特征蛋白羰基含量随贮藏时间的变化规律，并探讨了这些变化与肉品嫩度之间的关系。然后，针对高氧气调包装和真空包装贮藏的鲜肉进行加热处理，研究了肌肉蛋白总羰基、特征蛋白羰基（α-aminoadipic semialdehyde，AAS）及席夫碱特征交联产物（lysinonorleucine，LNL）随不同加热条件的变化，明确了经过高氧气调贮藏的肉蛋白羰基化及其交联程度是否会受到加热的促进效应，进一步阐明了高氧气调包装下肌肉蛋白羰基化交联对肉品嫩度劣变所起作用。研究结果表明高氧气调包装环境所引起的肉品嫩度的下降与蛋白羰基化密切相关，然而冷藏阶段肉中蛋白的羰基化可能很大一定程度上来自于脂肪氧化产物（如MDA）与蛋白质的共价结合，而非相关氨基酸残基的直接氧化。另一方面，随着加热温度的升高肉中特征蛋白羰基产物AAS和席夫碱交联产物LNL显著增加，并且高氧气调包装组的含量明显高于真空包装组。这些结果表明蛋白羰基化交联对肉品嫩度的影响可能主要与MDA引起的蛋白交联相关，或者主要发生在肉品加热阶段。该项目将为解决高氧气调包装冷鲜肉嫩度劣变的问题提供理论指导，并有助于推动我国冷鲜肉包装行业的健康发展。