宰后肌肉蛋白氧化介导的滴水损失形成机制

The drip loss of post-mortem muscle leads to weight loss and reduces the juiciness, tenderness and appearance quality of the meat and results in great losses to the meat production. At present the studies of muscle water holding capacity(WHC) were mostly concentrated on the post-mortem glycogen anaerobic metabolism, few studies on the relationship between drip loss and protein oxidation in the mature process of post-mortem muscle.This project uses post-mortem pig longissimus dorsi as the experimental material, comparative analysis the changes of post-mortem muscle protein oxidation apparent characteristic features under different oxidation conditions and combines with the determination of muscle water NMR relaxation, to clarify the effects of the mediated charge effects of protein oxidation on the muscle water holding capacity.By using SDS-PAGE protein electrophoresis and Western blot analysis, combining with scanning electron microscopy to clarify the effects of oxidation-mediated protein cross-linking polymerization effects on the microscopic space structure of the muscle bundles. Revealing the relationship between protein oxidation and muscle hydraulic conductivity. Using controlled Fe3+-H2O2-Vc oxidation system to imitate myofibrillar protein oxidation to confirm the protein oxidation-mediated charge effects and space effects. By check experiment and simulation test verification to answer the effects of protein oxidation on the formation of muscle flowing water's "pool" and "drip channel". The results of this project would elucidate the protein oxidation-mediated mechanism of drip loss and provide a new theoretical basis to control drip loss of post-mortem muscle.

畜禽宰后肌肉滴水损失导致失重，降低了肉的嫩度、多汁性和外观品质，给肉类生产造成很大损失。目前对宰后肌肉持水性的研究主要集中在糖原无氧代谢方面，而对宰后肌肉成熟过程中蛋白氧化与滴水损失的关系研究较少。项目以宰后猪背最长肌为材料，通过对不同处理条件下的宰后肌肉蛋白氧化特征量变化规律的比较分析，结合肌肉中水的NMR弛豫测定，阐明蛋白氧化介导的电荷效应对肌肉持水性的影响；采用SDS-PAGE蛋白电泳和Western blot分析，结合扫描电镜观察，阐明氧化介导的蛋白交联聚合效应对肌束间空间构象的影响，揭示蛋白氧化与肌肉导水性的关系；采用铁-过氧化氢-抗坏血酸氧化体系对肌原纤维蛋白进行模拟控制氧化，确证蛋白氧化介导的电荷效应和空间效应。通过对比试验与模拟验证，回答蛋白氧化在肌肉可流动水"库"与"渠"形成中的作用，阐明蛋白氧化介导的滴水损失形成机制，为宰后肌肉滴水损失控制提供新的理论依据。

项目以宰后猪背最长肌为材料，通过低场核磁共振技术测定肌原纤维蛋白凝胶的横向弛豫时间以及水分子氢质子密度成像图谱，研究凝胶中结合水、不易流动水和自由水3种状态水的组成、含量及分布，建立了一种测定肌原纤维蛋白凝胶的保水性及其水分含量的方法；通过羟自由基氧化体系下不同H2O2浓度对蛋白氧化程度及MP凝胶白度、持水力、质构特性（texture profiles analysis，TPA）与弹性模量等特征指标的影响研究，确证了·OH氧化体系中肌原纤维蛋白氧化会影响其凝胶形成，破坏蛋白凝胶结构，降低凝胶功能，阐明蛋白氧化与肌肉持水性之间的关系，为宰后肌肉滴水损失控制提供新的理论依据。