微/纳尺度复合凝聚物形成、稳定机制与选择性包埋

The microcapsule prepared by complex coacervation confers plenty of adervantages, like controlled releasing and the capability of resisting high temperature and high humility. However, due to the problems of the micrometer size distribution and the unstable dispersion of suspension, such technology encounters severe restriction in application of liquid food. In order to disclose the formation mechanism of complex coacervates with different sizes and the entrapment of core materials, the following aspects will be applied for the present study. Firstly, the analysis of zeta-potential, turbidity titration, dynamic light scattering (DLS) and microscopic observation will be employed to discuss the formation possibility of complex coacervates between common used proteins and polysaccharide with variable anion groups, much more attention will be paid on the essential structure and physiochemical features of wall materials specifically suitable to the nanocapsule formation. Combined with isothermal titration calorimetry (ITC), circular dichroism (CD), Raman spectroscopy and small angle X-ray scattering (SAXS), the regulation mechanism will be evaluated for the formation and stableness of complex coacervates with different sizes from the view of driving force, secondary bond and conformational transition. Finally, hydrophobic probe and fluorescence staining together with confocal laser scanning microscope (CLSM) will be applied to investigate the binding mechanism between complex coacervates and core material. The statistic analysis method called partial least squares regression (PLSR) will be used to study the selective entrapment of variable core materials by complex coacervates from different wall materials and determine the characteristic physicochemical parameters of wall and core materials for suitable encapsulation. Based on such fundamental research, we will be able to further understand the mechanism of complex coacervation and directional prepare microcapsule or nanocapsule for flavor volatile substance or bioactive food compounds. The achievements will advance the processing technology in food industry and the maintenance of human health.

以复合凝聚物为壁材的微胶囊能耐受高温高湿环境并具控释特性，但微米尺度的粒径分布和悬浊液的分散不稳定性限制了其在液态食品中的应用。本项目采用zeta-电位、浊度滴定、动态激光光散射、显微图像等分析方法，探讨利用常见的蛋白质与带不同负电基团的多糖反应形成不同尺度复凝物的可能性，重点研究制备纳米胶囊的壁材所需具备的结构与带电性质；结合等温滴定量热法、圆二色谱、拉曼光谱、小角X-射线散射等手段，从反应驱动力、次级键作用及分子构像变化等微观水平揭示不同尺度复凝物形成与稳定的调控机制；采用疏水性探针、荧光染色联合激光共聚焦显微技术，研究复聚物与芯材的结合机制，应用偏最小二乘回归（PLSR）方法明晰复聚物包埋芯材选择性的关键影响因素。本项目的研究将深化当前对复合凝聚机理的认识，并有望实现微/纳米不同尺度的胶囊化功能精油或功能因子的可控制备，为食品领域的产品升级及人体健康的维持提供理论指导和技术支持。

以复合凝聚物为壁材的微胶囊能耐受高温高湿环境并具控释特性，但微米尺度的粒径分布和悬浊液的分散不稳定性限制了其在液态食品中的应用。本项目采用zeta-电位、浊度滴定、动态激光光散射、显微图像等分析方法，探讨了利用常见的蛋白质与带不同负电基团的多糖反应形成不同尺度复凝物的可能性，重点研究了制备纳米胶囊的壁材所需具备的结构与带电性质；结合等温滴定量热法、圆二色谱、拉曼光谱、小角X-射线散射等手段，从反应驱动力、次级键作用及分子构象变化等微观水平揭示了不同尺度复凝物形成与稳定的调控机制；采用疏水性探针、荧光染色联合激光共聚焦显微技术，研究了复聚物与芯材的结合机制。.结果表明,通过控制体系的pH在3～4.5范围以及蛋白/多糖比例可形成不同尺度的复凝物。离子多糖如高甲氧基果胶、羧甲基纤维素钠、硫酸软骨素、壳聚糖的空间位阻效应对纳米颗粒的形成以及稳定性具有重要作用。蛋白糖基化有助于形成纳米尺度并且具有环境耐受性的纳米胶囊，而接枝度的不同造成了纳米颗粒稳定性的显著差异。微米级复凝物形成阶段以放热信号为特征，主要受两种大分子之间静电相互作用产生的热焓变化控制。离子多糖、葡聚糖接枝均导致蛋白质的内源荧光淬灭,表明共价结合的葡聚糖链和静电结合的离子多糖分子以空间位阻效应参与到纳米颗粒形成过程。静电相互作用是促进了微米级颗粒形成的最主要作用力，空间位阻效应和疏水相互作用则是纳米颗粒形成与稳定的关键调控因素。疏水性芯材肉桂醛、叶黄素等主要分布在复合凝聚物微/纳米胶囊的疏水小区，疏水相互作用是主要作用力。明胶等蛋白分子主要分布在多核胶囊的界面上，形成致密的保护层，从而发挥着提高敏感芯材稳定性的作用。.本项目的研究深化了当前对复合凝聚机理的认识，并实现了微/纳米不同尺度的胶囊化功能精油或功能因子的可控制备，可为食品领域的产品升级及人体健康的维持提供理论指导和技术支持。.