鱼肉肌球蛋白在快速介电加热作用下的结构变化及相关机制研究

Low-salt diet is becoming the new health requirement. Rapid dielectric heating process which is a promising alternative to conventional heating method for producing high quality low-salt surimi products, is becoming of increasing interests in the aquatic products processing industry. Myosin plays a main role in the process of the gel-forming, but the change mechanisms of structure response to dielectric heating is still a lack of clear understanding. In this study, structural changes of myosin proteins from Hypophthalmichthys molltrix treated by dielectric heating were determined by using circular dichroism, spectrum technology et al, combining with SEM analysis, gel properties analysis, LF-NMR and MRI analysis, et al. This study first put forward to figure out myosin conformational changes on the response mechanism of dielectric heating effect, illuminate the correlation of fish myosin gel reticulation structure induced by dielectric heating and molecular forces and verify the influence of non-thermal effect for myosin structure; Meanwhile, temperature distribution in surimi products based on computer vision and model foods will be observed, ultimately, the quantitative and qualitative relationship of the myosin gelation properties with their structural changes and processing parameters (heating speed) were explored by correlation analysis. Based on the understanding of the myosin structural changes during dielectric heating process, different heating model will be established to produce the low salt surimi products with particular structures and ideal functional properties. This study will lay the foundation for inhibition of fish protein gel degradation with rapid dielectric heating and control theory, provide a new technology insight to the low-salt fish protein processing system, make further progress on dealing with the bottleneck which restricts the development of this industry, upgrade of the industrial structure.

低盐饮食成为新的健康需求。快速介电加热代替传统的热处理方式以获得高品质的低盐鱼糜制品，是水产品加工的热点。肌球蛋白在鱼糜形成过程中起主要作用，但尚未了解基于介电加热的肌球蛋白结构演化规律。本研究选取鲢鱼鱼肉肌球蛋白为研究对象，在实现介电加热速率精确控制与模拟的基础上，利用圆二色谱分析、光谱分析等研究肌球蛋白结构变化规律，结合电镜扫描分析、凝胶特性分析、低磁场核磁共振分析等，首次提出明确肌球蛋白分子结构变化与介电加热参数的相关性，阐明肌球蛋白介电加热诱导凝胶网状结构形成与分子作用力相关性，验证非热效对肌球蛋白结构的影响；同时通过介电特性分析、计算机模拟等手段研究内部热量分布状态的变化规律，最终揭示鱼肉肌球蛋白凝胶特性与加工参数、结构变化的相关性并实现调控。本研究为快速介电加热技术抑制鱼肉蛋白凝胶劣化及控制理论奠定基础，进一步解决制约低盐鱼糜制品行业发展的瓶颈问题，促进产业层次升级。

降低加工食品中的食盐用量一直是国内外关注的问题，但是对于凝胶类鱼糜制品来说，传统加工过程中为了促进鱼肉蛋白的凝胶化过程，需要添加3%左右的食盐，降低盐分含量不但会导致咸度的下降，更影响蛋白质功能特性进而降低产品品质。本项目主要以中盐提取的鲢鱼肉功能性蛋白和低盐鲢鱼糜为研究对象，使用快速介电加热和快速介电加热辅助水浴加热诱导肌球蛋白，尤其是快速介电加热对传统二段加热升温阶段的替代，系统研究和分析了鱼糜原料中功能性蛋白——肌球蛋白在不同热处理组合模式中的差异和分子结构演化机理。提出了通过改变传统热传导方式这一有效的手段，改善低盐鱼糜制品加工过程存在的蛋白凝胶化速度慢、凝胶强度差、容易出现凝胶劣化的问题。明确了介电加热非热效应对鱼肉肌球蛋白分子结构变化规律的影响；从分子水平上揭示肌球蛋白的热聚集行为、水分状态与三维网络结构形成的相关性；揭示了鲢鱼鱼肉肌球蛋白凝胶特性与介电加热加工参数、结构变化的相关性。研究成果为生产鱼糜工艺提供了理论依据，对更好地控制肌球蛋白分子的稳定性提供了依据，为低盐水产蛋白食品的研发提供了新的思路。应用上突破了单纯在产业上使用分子交联剂（添加外源性蛋白酶或者使用内源性蛋白酶抑制剂等）成本高、非连续性、耗能等局限，从理论层面明确了快速介电加热成为抑制低盐鱼糜制品凝胶劣化的有效手段，使介电加热技术成为充分开发利用低盐低值原料资源，促进水产品产业发展的一条有效途径。