利用岩藻聚糖硫酸酯构建多层乳液型食品营养载运体系的基础研究

Fucoidan exists in various marine food resources such as brown algae and sea cucumber. Although its bioactivities have been widely and extensively studied, reports on the functions of fucoidan at other aspects are still rare, which limits the further utilization of this polysaccharide. In our previous study, the potential of fucoidan in fabricating multilayer emulsion delivery system has been verified, and under this background, this project is planning to conduct a series of research on the key scientific issues related to the development of fucoidan-based multilayer emulsion. Fucoidans with different primary structure, conformation, and physicochemical properties will be employed as materials to fabricate multilayer emulsion with the fish oil primary emulsion. By a combination of various techniques including microelectrophoresis, covalent florescence labelling, confocal laser scanning microscopy and isothermal titration calorimetry, this project will elucidate the interaction of fucoidan and primary emulsion via stability map, microstructure, changes in thermodynamics parameters, and theoretical model, examine the possible replacement of fucoidan on the interface of multilayer emulsion by polysaccharides in food matrix, clarify the influence of pH and NaCl on the properties of multilayer emulsion, and evaluate the digestive characteristics by using in vitro and in vivo models. This project will clarify the rules existing in the interaction of fucoidan and emulsion, and reveal the relationship between the properties of fucoidan-based multilayer emulsion and molecular characteristics of fucoidan. Furthermore, this project will realize the rational design of multilayer emulsion based on fucoidan, and thus expand the application of fucoidan.

岩藻聚糖硫酸酯(FUC)存在于褐藻、海参等多种海洋食品原料中，其生物活性得到广泛且深入的研究，但其他功能却普遍缺乏关注，限制着该多糖的进一步应用。项目组前期验证FUC在构建多层乳液方面具有潜力，本项目拟围绕FUC多层乳液构建过程中的关键科学问题展开研究，以具有不同一级结构、空间构象及物化性质的FUC为实验材料，与载有鱼油的单层乳液复合构建多层乳液，综合激光微电泳、FUC共价荧光标记、激光共聚焦、等温滴定量热等技术，从稳定相态图、微观结构、热力学变化、理论模型等多个角度研究FUC与单层乳液的相互作用，同时深入探究食品基质多糖对多层乳液界面上FUC的置换，考察基质pH及NaCl对多层乳液的影响，结合体外、体内模型评价FUC多层乳液的消化吸收特性。项目将首次阐明FUC与单层乳液相互作用的规律，揭示FUC多层乳液性质与FUC分子特征间的关系，实现FUC多层乳液的理性构建，为FUC的应用开拓新途径。

岩藻聚糖硫酸酯（FUC）是一种重要的海洋多糖，其构建多层乳液这一新型营养运载体系的可行性先前已得到验证。本项目围绕FUC构建多层乳液过程中的关键科学问题展开研究，制备出具有不同一级结构、空间构象及物化性质的FUC为实验材料，系统探索了FUC与单层乳液相互作用的规律，建立了FUC分子特征与其多层乳液构建性能之间的构-效关系。利用特色工具酶将FUC降解至不同分子量，发现随着分子量的降低，FUC的刚性和尺寸不断降低；高分子量的FUC与乳液相互作用的pH区间宽，且使单层乳液饱和的浓度较低；与此同时，高分子量制备的多层乳液具有较好的贮藏稳定性和盐稳定性。利用酶解的方式将不同一级结构（有无支链、硫酸酯化位点不同）FUC的分子量降解至同一水平，发现硫酸酯化位点对FUC与乳液相互作用的影响有限；相比直链FUC，支链FUC使乳液饱和的浓度较高，制备的多层乳液的盐稳定性更强。证实褐藻胶、卡拉胶、果胶等多种食品基质多糖均不能置换多层乳液界面上的FUC，说明FUC构建的多层乳液在食品基质稳定性方面具有优势。利用体内外模型比较了不同分子特征FUC构建的多层乳液的消化吸收特性，随着FUC分子量的降低，FUC在体外提升乳液初始消化速率的效果和在体内抑制吸收的效果逐步降低，FUC一级结构上的差异对乳液消化吸收的影响有限。在完成项目原定计划的基础上，还揭示了不同类型多糖与乳液相互作用的规律，利用“自上而下”的策略克隆表达了多种新型多糖酶，为获取不同类型、相同分子量水平的多糖提供了关键工具；发现在硫酸化的半乳聚糖中ι-卡拉胶与乳液有较强的相互作用，其制备的多层乳液具有最高的盐稳定性；羧酸多糖在制备多层乳液的过程中最容易发生架桥和损耗絮凝；κ-卡拉胶可以显著提高多层乳液的消化程度。在项目资助下，现已发表SCI论文14篇，其中JCR一区论文9篇，申请发明专利2项。研究成果可为利用多糖构建特定功能的多层乳液提供理论支撑。