鲢鱼肌原纤维蛋白热诱导凝胶对腥味物质的结合作用机制研究

Freshwater fish has strong fishy odor, which has always been one of the bottlenecks restricting the surimi processing in China. During the heat processing of surimi-based product, the changes of protein conformation and gel network structure have siginificant influence on the binding and release of fishy odor compounds, however the related mechanism was still unclear. This project selects silver carp as object, the binding sites and molecular forces of characteristic fishy odor compounds and myofibrillar protein will be explored by mass spectrometry, spectrum technology and frozen electron microscopy. The change of myofibrillar protein conformation, aggregation behavior and gel properties under different heat-induced conditions will be investigated by Raman spectroscopy, differential scanning calorimetry, dynamic rheometer, atomic force microscope, confocal laser scanning microscope and transmission electron microscope, and the effects of myofibrillar protein heat-induced unfolding and aggregation on the binding sites of fishy odor compounds will be clarified. Furthermore, the interaction between fishy odor compounds and myofibrillar protein gels, as well as relationship between protein gel network structure and fishy odor compounds binding capacity will be studied. The project aims to reveal the binding evolvement rule of fishy odor compounds and myofibrillar protein and illustrate the mechanism of protein heat-induced gelation process on the binding of fishy odor compounds. The project can provide theoretical basis for the control of fishy smell and improving the flavor and quality of surimi-based product, and make contributions to innovating and enriching freshwater fish surimi processing theories.

腥味重一直是制约我国淡水鱼鱼糜加工产业发展的瓶颈。鱼糜制品热加工过程中，蛋白质分子构象变化、凝胶网络结构改变对腥味物质的结合与释放具有重要影响，但作用机制尚不清楚。本项目拟以鲢鱼为研究对象，采用质谱、光谱和冷冻电镜等技术研究鲢鱼鱼糜中特征腥味物质与肌原纤维蛋白的结合位点、作用力类型；通过拉曼光谱、DSC、动态流变仪、AFM、CLSM和TEM等技术细致表征不同热诱导条件下肌原纤维蛋白构象变化、聚集行为和凝胶特征，解析肌原纤维蛋白热诱导展开与聚集过程对特征腥味物质结合位点的影响规律，进一步分析腥味物质与蛋白凝胶之间的作用方式，建立凝胶网络结构特征与腥味组分吸附特性的内在联系。本研究旨在揭示肌原纤维蛋白对腥味物质结合作用的演变规律，阐明鲢鱼肌原纤维蛋白热诱导凝胶对腥味物质的结合作用机制，为鱼糜制品中腥味物质的调控及风味品质改善提供理论依据，对创新和丰富淡水鱼鱼糜加工的基础理论具有重要意义。

腥味重一直是制约我国淡水鱼鱼糜加工产业发展的瓶颈。肌原纤维蛋白和肌球蛋白作为直接底物，不仅影响鱼糜制品的凝胶特性，而且影响腥味物质的释放，但目前关于蛋白基质与腥味物质相互作用的研究关注较少。为了阐明鱼糜热加工中腥味物质与蛋白基质的相互作用机制，本项目通过建立鱼肌原纤维蛋白/肌球蛋白-腥味化合物作用模型体系，采用顶空-气相色谱/质谱法（HS-GC-MS）、分子模拟和光谱等技术研究了鱼肉蛋白与典型腥味物质之间的结合作用特征；通过拉曼光谱、荧光光谱、SDS-PAGE凝胶电泳、DSC、动态流变仪、Zeta电位分析仪和HS-GC-MS等研究了不同热诱导条件下蛋白质构象变化、聚集行为及其对腥味化合物结合作用的影响，阐明蛋白热诱导展开与聚集过程对特征腥味物质结合作用的影响规律。研究结果表明，鱼肉蛋白基质与所选腥味化合物之间的结合能力随着碳链长度及不饱和度的增加而显著增大，且醇类的吸附能力显著低于醛类；疏水性互作用、氢键及共价键是鱼肌球蛋白与所选腥味化合物结合的主要方式。热处理过程中，蛋白质结构和表面性质的变化会显著影响其与腥味化合物的结合作用。在加热初期，由于蛋白表面疏水性和总巯基含量的增加，以及蛋白二级结构的展开导致活性氨基酸、巯基基团和疏水结合位点的暴露，从而使蛋白质对腥味化合物的结合能力增强。然而，长时间的加热会导致蛋白质重新折叠，蛋白聚集程度加速，从而减少疏水性结合位点，减弱蛋白质与风味化合物的结合作用。脱乙酰魔芋葡甘聚糖（DKGM）能够与肌球蛋白形成复合物，并能促进蛋白结构的展开及分子间的交联作用，增强肌球蛋白的凝胶形成能力；DKGM的添加促使肌球蛋白的α-螺旋结构向β-转角、β-折叠转变，使热诱导肌球蛋白的表面疏水性和总巯基含量增加，同时促进蛋白的热聚集作用；DKGM的添加促进肌球蛋白结构的展开，暴露出更多的疏水性基团和巯基基团，从而增强其对腥味化合物的结合作用。