基于玻璃化转变理论的魔芋寡糖保护鱼糜蛋白冷冻变性的分子机制

水产品蛋白冷冻变性一直是国内外关注的焦点。添加糖类抗冻剂可有效改善水产品蛋白的冻藏稳定性，是目前保护水产品蛋白冷冻变性的主要途径。针对传统糖类抗冻剂如蔗糖甜味高、热量大的问题，本项目提出添加新型魔芋寡糖KOG实现鱼糜蛋白冷冻变性的保护作用。通过分析KOG对冷冻鱼糜蛋白理化、结构、凝胶、流变特性影响，探索KOG对鱼糜蛋白冷冻变性的影响。针对抗冻剂与蛋白及冰晶之间相互作用分子机制不明确的问题，本项目提出借助玻璃化转变理论和分子动力学模拟方法阐明KOG保护鱼糜蛋白冷冻变性的分子机制。通过分析冷冻鱼糜热动力学和机械特性变化，分析KOG与鱼糜肌球蛋白及冰晶之间相互作用，建立鱼糜玻璃化转变与鱼糜分子互作的多因素相关性分析，揭示KOG对冷冻鱼糜冰晶成核与生长以及蛋白空间结构影响机制，阐明KOG保护鱼糜蛋白冷冻变性的分子机制。本项目将丰富和完善糖类抗冻剂冷冻保护机理，为改善水产品蛋白冷冻变性提供理论指导。

The aquatic proteins denaturation has been an important issue around the world. The addition of the cryoprotectants of sugars could effectively improve the stability of aquatic proteins during frozen storage, which makes it a principal pathway to protect aquatic proteins from denaturation. However, the traditional cryoprotectants of sugars such as sucrose are sweet and of high calorie. In the present project, a novel sugar, konjac oligo-glucomannan (KOG), is used as cryoprotectant to protect surimi proteins from frozen denaturation. The effect of KOG on the physicochemical, structural, gel and rheological properties of surimi proteins during frozen storage is analyzed, to investigate the effect of KOG on the frozen denaturation of surimi proteins. On the other hand, the interactions between cryoprotectant and aquatic protein, cryoprotectant and ice crystal are still unclear. The present project uses glass transition theory and molecular dynamics simulation, to elucidate the molecular mechanism of KOG protecting surimi proteins from denaturation. The thermodynamics and mechanical properties of frozen surimi are analyzed, and the interactions between KOG and surimi myosin, KOG and ice crystal during frozen storage are analyzed. The multivariate correlation analysis between surimi glass transition and surimi molecule interactions is developed, to reveal the mechanism of the effect of KOG on the nucleation and growth of ice crystal, and surimi proteins conformation. Finally, the molecular mechanism of KOG protecting surimi proteins from denaturation is elucidated. The present project would enrich and improve the cryoprotective mechanisms of cryoprotectants of sugars, and would also provide theoretical guidance to improve aquatic proteins denaturation during frozen storage.