宰后变性僵直横桥形成对猪肉保水性的影响机制研究

宰后降温不及时会加速猪肌肉代谢，导致保水性下降，严重损害猪肉的经济价值和营养价值，因此研究猪肉僵直调控已成为人们日趋关注的热点领域。本项目前期研究发现，僵直横桥结构在PSE诱导条件下变性，失去遇ATP时的解离能力，是导致粗细肌丝间距收缩，保水性降低的机制之一，但具体作用机制尚不明确。由此，申请人提出宰后变性僵直横桥受胴体温度与组织内pH协同调控，进而影响保水性的科学假说。项目将在明确猪肌肉僵直横桥连接速率与保水性关系的基础上，利用肌肉生理学、生物化学测量手段（肌张力、ATPase活性、圆二色光谱等）揭示变性横桥生理生化性质在温度与pH协同作用下的动力学变化规律；采用物理及生化表征方法（表面净电荷、疏水基团、氨基酸侧链修饰等）阐明变性横桥影响保水性机制。本研究结果将丰富僵直横桥对保水性影响机制的理论基础，为宰后肌肉僵直调控体系的建立提供指导。

Insufficient post-mortem chilling regime will accelerate muscle metabolic rate after slaughter, which will result in profound reduction in water-holding compacity, creating dramatic economic and nutritional loss to pork. According to our previous study, rigor cross-bridges denatured significantly under PSE meat-induction condition, being unable to dissociate even when ATP is present. The denaturation led to the lattice spacing compression between thick and thin filaments, which reduced water-holding capacity subsequently. However, the mechanism still remains unclear. Therefore, the current project proposes a hypothesis that the properties of rigor-cross bridges are greatly influenced by carcass temperature and intracellular pH, and thereby any alterations occurred in rigor-cross bridges will have impacts on water-holding capacity of meat. The aim of the present project is to first study the relationship between the rigor cross-bridge attachment rate post mortem and water-holding of meat. In the second part, the kinetics of rigor cross-bridge denaturation corresponding to different pH and temperatures condition will be investigated using muscle physiology and protein biochemistry techniques (fibre force, ATPase activity, circular dichroism spectroscopy, etc.). At last, the physical and biochemical impacts of cross-bridge properties on water-holding capacity will be elucidated by measuring myofibrillar protein surface charges, hydrophobicity, amino acid side-chain modifications, etc. The results from the current project will add new theoretical knowledge on the mechanism explaining the influence of post-mortem rigor cross-bridge attachment on water-holding compacity. In addition, the current project will support future studies on carcass rigor process control and meat quality.