界面张力对单分散微囊构建过程及其核壳结构的影响机制

Monodispersed core-shell structure microcapsules, prepared with hydrophilic and hydrophobic phases, have various application potentials in the fields of cereal and oil foods and food ingredients. During the preparation of monodispersed microcapsules, interfacial tension is a key factor that governs the formation of double emulsions, the molecular assembly of components in outside dispersed phase and the characteristics of core-shell structure. Here, we will prepare monodispersed water-in-oil-in-water double emulsions using the microfluidic method, following by removing the solvent in outside dispersed phase and obtaining the monodispersed microcapsules with core-shell structure. Interfacial tensiometer will be used to study the function relationship between the hydrophilic/hydrophobic interfacial tension and the influencing factors such as surfactant concentration. Then, a method for regulation of hydrophilic/hydrophobic interfacial tension will be acquired. Thereafter, high-speed camera, laser granulometer and interface rheometer will be used to explore the relationship between the interfacial tension and the preparation features of double emulsions (e.g., formation process, monodispersity and stability). Also, small/wide angle X-ray scattering and SEM will be applied to disclose the correlation of the interfacial tension alterations to the molecular assembly of components in outside dispersed phase during solidification and to the core-shell structure characteristics (size, morphology, shell thickness, shell compactness and ordering degree). Based on these investigations, how interfacial tension affects the fabrication of monodispersed microcapsules and their core-shell structural features will be revealed. This work will provide a theoretical basis for the rational design and preparation of high-quality monodispersed microcapsules.

亲疏水两相所构建的单分散核壳结构微囊在粮油食品和食品配料领域具有广泛的应用前景。微囊构建过程中界面张力是双重乳液形成、分散相组分的分子组装行为及由此形成的核壳结构特征的决定性因素。本项目拟采用微流控法制备单分散水包油包水双重乳液，移除乳液外分散相的溶剂使其固化，得到单分散核壳结构微囊；采用界面张力仪，建立亲/疏水相间界面张力与表面活性剂浓度等因素的函数关系，获得界面张力的调控方法；采用高速摄像机、激光粒度仪和界面流变仪等，研究界面张力与双重乳液的构建效果（形成过程、单分散性、稳定性等）的关系；利用同步辐射小角/广角X射线散射和扫描电子显微镜等，研究界面张力变化与外分散相固化过程中组分的分子组装行为及形成的核壳结构特征（尺寸、形貌、壁厚、致密性、有序度等）的相关性，揭示界面张力影响单分散微囊构建过程及其核壳结构的机制。本研究将为设计与制备高品质单分散核壳结构微囊提供理论依据。

亲疏水两相所构建的单分散核壳结构微囊在粮油食品和食品配料领域具有广泛的应用前景。核壳结构微囊的单分散性和包封率不高，导致其应用效果不稳定。本项目采用 “双重乳液构建-壳层凝胶固化-壳层脱水干燥”方法制备核壳结构微囊。研究结果如下：（1）搭建了微流控系统，成功制备了单分散双重乳液；从微尺度流体形变的角度，明确了界面张力是影响单分散双重乳液制备的关键因素，并建立了亲/疏水相间界面张力的调控方法；阐明了三相流体流速、添加物种类和浓度对双重乳液形成过程的影响。（2）建立了双重乳液亲水壳层相（琼脂/魔芋葡甘聚糖复配体系）凝胶温度点的调控方法。即：黄原胶、卡拉胶等组分通过与魔芋葡甘聚糖发生协同增效作用形成凝胶网络，该网络与琼脂自身凝胶网络共同形成互穿网络，提高了复配体系的凝胶温度。淀粉、刺槐豆胶、结冷胶等组分与魔芋葡甘聚糖分子链发生缠结，后与琼脂形成半互穿网络凝胶，降低了复配体系的凝胶温度。聚乙烯醇等分子量相对较小的组分，虽然与魔芋葡甘聚糖、琼脂发生分子链缠结，但其存在对琼脂分子自身形成网络的阻碍作用较小，并未影响其凝胶温度点。（3）基于壳层“溶胶-凝胶-薄膜”多相态分子链缠结与相互作用规律，建立了多糖基核壳结构微囊壳层特性和单分散性的调控方法。即：分子间协同增效作用增强核壳结构微囊壳层的拉伸强度，分子间缠结作用增强壳层的断裂伸长率。在此基础上，制备了包封率可控、单分散性好的核壳结构微囊，在香精香料包埋方面呈现良好的应用效果。研究成果发表SCI论文10篇，中文核心论文1篇，获得湖北省科技进步二等奖1项（序3），申请发明专利1项，培养硕士研究生3名。