神经酰胺复合凝胶体系改善油凝胶特性的自组装机制研究

Oleogels are being widely studied in structuring edible oils and providing novel routes for potential hard-stock fat replacement with low saturated and zero trans fats. Ceramides have been reported as a remarkable organogelator with numerous beneficial health effects. However, it crystallizes into fibrous network that is very different from colloidal fat crystal network, and the cost is considerably high, which hinders the further development of ceramide as an edible oil structurant. In order to improve the gelation behavior of ceramide oleogels and reduce the cost, co-gelators will be added to fabricate a mixed-gelator system to modulate the molecular packing and crystal morphology to create more similar properties as colloidal fat crystal networks. However, the mechanism behind co-assembly is not clear. In this project, modern analytical techniques will be utilized to characterize the self-assembled supramolecular networks of the mixed system and probe the gelation mechanism behind co-crystallization. Additionally, different oil phase will be investigated to illuminate the influence of solvent on molecular packing, self-assembled supramolecular networks and macroscopic properties of the resultant gel. These physiochemical properties will be correlated to solubility parameters to establish predictive models in the aspect of solvent for further elucidation of gelation mechanism of the mixed-gelator system. With the completion of this project, fundamental knowledge will be gained about how to manipulate the co-assembly of mixed gelators to achieve desirable crystal morphology and macroscopic properties, as well as providing guidelines for the product development of healthy fat replacers comprised of mixed-gelator system.

油凝胶作为塑性脂肪替代物为开发零反式、低饱和脂肪酸的脂肪产品提供新思路。神经酰胺是一种具有健康功效的新型食品级油脂凝胶剂，但其凝胶过程中形成的晶体结构有缺陷限制了其应用。本项目通过添加复合凝胶剂，改善原单一体系晶体结构使其更接近塑性脂肪。但复合凝胶体系的增效过程不清晰，形成机制也不明了。本项目首先利用电子显微镜、X射线衍射、核磁共振氢谱等结构表征手段全面探究复合凝胶体系构建过程中不同层面网络结构随凝胶剂体系的变化规律。在此基础上，探讨不同基料油对上述复合凝胶体系微观网络结构及宏观特性的影响，并将其与溶解度常数关联，建立模型对基料油影响复合体系中凝胶剂分子自组装的过程进行量化评价。最终阐释如何利用复合凝胶体系改善神经酰胺油凝胶特性这一科学问题。该研究为复合凝胶剂在植物油中的自组装机制奠定理论基础，为合理设计复合凝胶体系构建健康脂肪产品提供指导。

油凝胶作为塑性脂肪替代物为开发零反式、低饱和脂肪酸的脂肪产品提供新思路。神经酰胺是一种具有健康功效的新型食品级油脂凝胶剂，但凝胶过程中形成的晶体结构有缺陷限制了其应用。本项目利用复合凝胶剂的共结晶构建神经酰胺-卵磷脂复合油凝胶体系，通过调控体系中的微观网络结构，改善单独使用不能凝胶、或者凝胶晶体结构和宏观性能不理想等问题。但复合凝胶体系的增效过程不清晰，形成机制也不明了。申请人利用电子显微镜、X射线衍射等结构表征手段全面探究复合凝胶体系构建过程中不同层面网络结构随凝胶剂体系的变化规律，通过分子间作用力及计算机模拟耗散动力学分析，发现神经酰胺和卵磷脂以1:1的摩尔比共组装，冗余的神经酰胺和卵磷脂以自分类方式形成基础结晶，通过氢键和范德华力的作用，与共组装的初晶纤维排列组装成不同的网络结构，导致不同的凝胶行为。在此基础上，申请人进一步研究了神经酰胺和卵磷脂共组装晶体的动力学生长过程，通过改良Avrami方程、Jeziorny方程、Ozawa方程和Mo方程等结晶动力学方程对该复合体系结晶过程进行拟合，得到的曲线可用于预测得到特定结晶度的凝胶体系所需的冷却速率和冷却时间。此外，申请人构建了水致复合油凝胶体系，进一步增强了神经酰胺-卵磷脂复合油凝胶体系的凝胶性能。研究了油相和水相性质对凝胶特性的影响。利用溶剂常数将基料油性质量化，并与体系弹性模量、结晶焓值以及氢键强度进行了关联，用于更好地调控凝胶特性。本研究从凝胶剂和基料油两方面阐释了复合凝胶剂自组装形成凝胶的机制，研究结果为复合凝胶剂在植物油中的自组装机制提供大量基础数据和重要的理论补充，为将来合理地设计复合凝胶体系构建健康的脂肪产品奠定基础。