纳米蒙脱土对挥发性精油微胶囊壁材的改性及控释机理研究

Volatile essential oil is usually microencapsulated in the application. In order to solve the defect of microcapsule wall material with natural macromolecules, the layered inorganic nano montmorillonite is added into the wall material, then the essential oil is encapsulated in the project. This design applies the montmorillonite wafer with larger diameter to thickness ratio to improve the mechanical property, barrier ability, heat resistance and moisture resistance of the natural macromolecules wall material, to improve the performance of the wall material, and to achieve better protection and controlled release of essential oil. In order to improve the composite ability of montmorillonite with natural macromolecules, and to cause macromolecules intercalating into montmorillonite interlayer with the fully stripped sheet. The montmorillonite was first modified by small molecule amino acid or sugar, then added to the natural macromolecule. The interaction of active groups with montmorillonite is studied, the effect of intercalation conditions on dispersion of montmorillonite wafer in natural macromolecules is discussed and the reinforcing mechanism of montmorillonite on nanocomposite is revealed. The effects of nanocomposite as wall materials on emulsifying properties, encapsulation efficiency, structural morphology, mechanical strength, stability and release properties of microcapsules were studied. The release kinetics of microcapsules encapsulating essential oil is investigated, and the mathematical model of the essential oil diffusion is established. The relationship between the wall material structure and the controlled release properties is obtained. The antibacterial and fresh-keeping abilities of microcapsules encapsulating controlled-release essential oil in food packaging is also studied. The project will provide theoretical support and practice guidance for the development of new wall materials for microcapsules encapsulating volatile essential oil.

挥发性精油常用微胶囊化技术进行包覆，为解决天然大分子作为微胶囊壁材的缺陷，本项目在壁材中加入层状无机纳米蒙脱土，对精油进行包覆。该设计利用具有较大径厚比的纳米蒙脱土晶片提高天然大分子壁材的力学性能、阻隔能力和耐热耐湿性，达到更好保护精油，调控释放的目的。为提高天然大分子与蒙脱土的复合能力，让大分子插层于蒙脱土晶片中，使片层充分剥离，先用小分子氨基酸或糖对蒙脱土进行修饰，再加入到天然大分子中，研究活性基团与蒙脱土的作用，探讨插层条件对蒙脱土晶片在天然大分子中分散的影响，揭示蒙脱土对天然大分子改性机理。研究纳米复合物壁材对精油乳化性能以及对微胶囊包埋效率、结构形态、机械强度、稳定性、释放性能的影响。考察精油微胶囊的释放动力学，建立精油扩散数学模型，获得囊层结构与控释性能之间的对应关系。并研究缓释精油微胶囊在食品包装中的抗菌保鲜应用。该项目将为挥发性精油微胶囊开发新型壁材提供理论支持和实践指导。

挥发性精油常用微胶囊化技术进行包覆，为解决天然大分子作为微胶囊壁材的缺陷，本项目在壁材中加入纳米蒙脱土或者其它纳米颗粒，对精油进行包埋，达到更好保护精油，调控释放的目的。该研究先在制备精油微胶囊的乳化过程中，将纳米颗粒加入到天然大分子溶液，经均质乳化后再干燥形成微胶囊，探讨纳米颗粒与天然大分子的相互作用，揭示纳米复合物壁材对精油乳化性能以及对微胶囊力学性能、阻隔能力和耐热耐湿性的影响。通过对单一天然壁材和复合纳米壁材性能的研究，发现天然大分子活性基团与纳米颗粒之间产生相互作用，形成了具有三维空间的网络结构，可有效抑制复合壁材的溶胀，提高了壁材的热稳定性、机械强度和阻水隔油的性能，能够在干燥过程中有效降低壁材的破裂，减少精油的泄漏，达到提高包埋率的效果。在鱼油微胶囊的壁材中添加纳米蒙脱土，提高了壁材包埋鱼油的效率，有利于减缓鱼油微胶囊在较高湿度和温度下的氧化，易于贮存。并且进一步研究了喷雾干燥法和锐孔－凝固浴法制备精油微胶囊的最佳工艺条件。. 精油在微胶囊中的释放介于扩散限制动力学和一级释放动力学之间，随着相对湿度和温度的增加，释放速率常数变大，壁材中添加纳米蒙脱土降低了精油释放速率，提高了释放活化能。精油累积释放曲线采用Ritger-Peppas扩散数学模型拟合，其拟合性很好，方程中的n值均小于0.45，属于Fick自由扩散。. 研究了纳米颗粒稳定的Pickering乳液，纳米颗粒在油水界面能提供良好的乳化效果，有效阻止液滴聚集，并且在高温下能保持乳液的稳定，在食品乳液的应用中纳米颗粒可以替代合成乳化剂。采用大豆蛋白颗粒稳定的乳液油凝胶，具有弹性凝胶网络构造，将其应用于肉糜中替代动物脂肪，肉糜的保水保油效果得到改善，有利于在蒸煮过程中抑制肉糜油脂的渗出。该项目为制备精油微胶囊开发新型壁材提供理论支持和实践指导。