基于蛋白质重组装的淡水/海水混合鱼糜凝胶协同增效机制研究

With the accelerated pace of life, the demand quantity of surimi products has increased year by year, but the main raw materials of marine fish resources are increasingly scarce. On the contrary, freshwater fish that can be used for surimi processing resources are very rich in China, and the price of them is low. Gel properties of freshwater fish surimi is worse than marine fish surimi, and how to improve it is one of the bottlenecks in the development of freshwater fish surimi. We and others have been found that the blended surimi from freshwater fish with marine fish could produce gel synergies under the proper conditions. Based on these findings we propose a hypothesis of “forces of protein intermolecular - changes of protein conformation - gel synergy of the blended surimi”. This project aims to analyse protein and amino acid composition of marine/freshwater blended surimi and the difference of endogenous transglutaminase, and study the effect of interaction among protein molecules on surimi gel network structure during the process gel forming, and explore the correlation between changes of protein conformation and gel synergies of blended surimi by modern instrumental analysis and molecular biotechniques and so on. Meanwhile, to reveal the gel synergies based on protein recombinant, the gel properties of blended surimi, conformational changes and aggregation characteristics of protein will be further study. The project can innovate and enrich surimi products processing theory, and also provide technology support for high value utilization of freshwater fish.

随着生活节奏加快，鱼糜制品需求量逐年增加，但其主要原料海水鱼资源却日益匮乏，相反我国淡水鱼资源丰富且价格低廉，而淡水鱼糜的凝胶特性较海水鱼糜差，提高凝胶特性成为淡水鱼糜产品开发的瓶颈之一。本课题组及前人研究发现，淡水/海水混合鱼糜在一定条件下可产生凝胶协同增效作用，据此本项目提出“分子间作用力-蛋白质构象改变-混合鱼糜凝胶协同增效”的假说。拟综合运用现代仪器分析、分子生物学等技术研究淡水/海水混合鱼糜蛋白质和氨基酸组成及内源性谷氨酰胺转氨酶的差异，分析鱼糜凝胶形成过程中蛋白质分子之间的相互作用力对凝胶网络结构形成的影响，探讨蛋白构象的改变与混合鱼糜凝胶特性协同增效的相关性。同时，对混合鱼糜凝胶化特性、蛋白质构象变化、蛋白质聚集特征等进行深入研究，从蛋白质重组装过程探明混合鱼糜凝胶协同增效机理。本项目可创新和丰富鱼糜制品加工理论，也可为淡水鱼高值化利用技术的发展提供支撑。

随着生活节奏加快，鱼糜制品需求量逐年增加，但其主要原料海水鱼资源却日益匮乏，相反我国淡水鱼资源丰富且价格低廉，而淡水鱼糜的凝胶特性较海水鱼糜差，提高凝胶特性成为淡水鱼糜产品开发的瓶颈之一。本课题组及前人研究发现，淡水/海水混合鱼糜在一定条件下可产生凝胶协同增效作用。本项目组综合运用现代仪器分析、分子生物学等技术，将海水鱼鱼糜（金线鱼鱼糜）与淡水鱼鱼糜（白鲢鱼鱼糜）混合，研究了混合鱼糜中蛋白质、氨基酸组成变化对凝胶形成作用力以及蛋白质构象的影响，同时分析了鱼糜凝胶形成过程中蛋白质构象的变化导致凝胶微观结构及粒径大小变化的原因，最后综合讨论了混合鱼糜凝胶协同增效作用的机理。结果表明：蛋氨酸与凝胶强度之间高度相关；丙氨酸、异亮氨酸、组氨酸、精氨酸和疏水性氨基酸总量与凝胶强度呈显著性相关；蛋氨酸、酪氨酸、组氨酸和精氨酸与非特异性关联、氢键之间呈显著性负相关。在鱼糜热凝胶形成过程中，混合鱼糜凝胶形成过程中凝胶强度与非特异性关联、氢键和α-螺旋呈极显著性负相关，与β-折叠、β-转角和无规则卷曲呈极显著性正相关，与二硫键呈不相关，网络结构较单一鱼糜更致密、均匀；混合鱼糜凝胶的网络结构更紧实。鱼糜形成的凝胶具有较好的凝胶特性，在凝胶形成过程中，氢键和非特异性关联含量大幅减少，肌球蛋白的表面疏水性得到增强，二级结构中的α-螺旋被破坏，随后有大量的β-折叠结构产生，肌球蛋白的大量聚集导致蛋白质的粒径增大。综上所述，混合鱼糜凝胶协同增效作用主要是由于氨基酸组成的改变，加强了蛋白质间的相互作用，促进了二级结构的转变，最终形成了更加均匀紧密的凝胶网络结构。