L-精氨酸对低离子强度下鱼肌球蛋白热胶凝的促进作用及其机制

Surimi-based product is one of the traditional aquatic food products. The level of salt at a range of 2~3% employed during processing of surimi products is important because it influences the amount of exuded protein obtained, which affects the protein aggregation and gelation. Surimi gels made with a low proportion of salt tend to be poorer because the protein is not adequately solubilized. How to reduce the amount of salt added into surimi product with advanced quality became an urgent issue for surimi industry. Previous studies indicated that L-arginine could improve the solubility of myosin and gelation properties of surimi at low ionic strength, whereas its improvement mechanism is still unclear. Therefore, the interactions between L-arginine and myosin from freshwater fish (Grass carp) at low ionic strength will be investigated. Then we will discuss how these interactions influence the structure and conformation of myosin at molecular level. The changes in the interactions between myosin and myosin, myosin and water during heat-induced aggregation and gelation will be also studied. The effects of L-arginine on the microstructure properties and macroscopic physical properties of myosin gel at low ionic strength will be investigated. These studies will provide some information for understanding the influence mechanism of L-arginine on solubility and the heat-induced gelation properties of myosin from freshwater fish at low ionic strength, and also provide theoretical basis for developing surimi products with reduced sodium content.

鱼糜制品是我国传统的水产食品。食盐是鱼糜制品加工中不可缺少的配料，添加量一般为2%~3%。如何在减少鱼糜制品中食盐添加量的同时又保证产品具有良好的品质，是低盐鱼糜制品生产中亟待解决的问题。前期研究发现在低离子强度下L-精氨酸可以提高草鱼肌球蛋白溶解性，并且可以改善低盐鱼糜凝胶特性，但机理尚不明确。因此，本课题拟以草鱼肌球蛋白为对象，在低离子强度下研究L-精氨酸与肌球蛋白的相互作用，揭示L-精氨酸对肌球蛋白的溶解性的影响及机制；分析热聚集和热胶凝过程中L-精氨酸诱导肌球蛋白-肌球蛋白相互作用、肌球蛋白-水之间的相互作用的变化规律；探讨L-精氨酸对肌球蛋白凝胶的微观结构和宏观性能的影响，构建低离子强度下肌球蛋白结构的变化与热聚集行为和凝胶特性之间的模型，从而从分子间相互作用的角度揭示L-精氨酸对低离子强度下肌球蛋白热胶凝的促进作用及其机制，同时也为新型低盐鱼糜制品的开发提供基础理论依据。

鱼糜制品是我国传统的水产食品。食盐是鱼糜制品加工中不可缺少的配料，添加量一般为2%~3%。如何在减少鱼糜制品中食盐添加量的同时又保证产品具有良好的品质，是低盐鱼糜制品生产中亟待解决的问题。本项目研究表明L-精氨酸可以增加肌球蛋白的溶解性，这种促溶作用下较低离子强度（50和150 mmol/L NaCl）下表现得尤为突出。L-精氨酸对肌球蛋白的增溶作用不仅仅来自于研究体系的pH值的增加，还和L-精氨酸与肌球蛋白相结合有关。L-精氨酸可以增加蛋白质分子间的静电斥力，使ζ电位绝对值增加，促进肌球蛋白解聚和分子链的伸展，暴露更多疏水基团，增加表面疏水性。添加0.65% L-精氨酸后，鱼糜凝胶的持水性、凝胶强度、质构特性、流变特性以及微观结构均得到了显著改善，L-精氨酸改善鱼糜的凝胶性能的原因是由它的强碱性以及它的基团与蛋白质分子之间发生相互作用共同所致。