水分迁移和分布与环糊精抑制淀粉链有序化重排关系探索

Starch riched food would have a bad quality during storage just because of the retrogrdation of starch. The essence of retrogradation is the ordering rearrangement of starch chain. The former research of our group showed that cyclodextrin could result in inhibiting order rearrangement of the starch chain, and water play important role during the process. While the role of water in cyclodextrin-starch system was neglected in the present mechnism for explaing the cyclodextrin antiretrogradation. Thus, based on the former research, this project aimed to explain some regulars including how do cyclodextrins with various cave diameter effect on water in cyclodextrin-water-starch triad, what the relationship between the water and the changement of starch crystal is, how do water distribution and migration in cyclodextrin-starch system. Based on the technics of NMR, molecular simulation, and X-ray, the experimental methods and analysis method from quantum chemistry were combined together to explain the regular and mechnism that starch crystal changement caused by water imgration and distribution in the cyclodextrin-starch system. This research will provide novel idea for studying antiretrogradation, which will be very meaningful for improving food quality during the starch processing.

高淀粉食品在储藏过程中因回生而导致食品品质劣化，淀粉回生的本质在于淀粉分子链的有序化重排。本项目前期研究表明环糊精能够有效抑制淀粉分子链有序化重排，且水分影响淀粉重排后的晶胞类型，而目前关于环糊精抗回生的作用机理探索忽略了水分在环糊精-淀粉体系中所发挥的作用。因此，在前期的研究基础上，本项目拟通过探索环糊精-水-淀粉三元体系中不同空腔大小环糊精对于水分子的作用规律、水分与淀粉晶体变化关系规律、水分在环糊精和淀粉分子间的分布和迁移规律，综合采用核磁共振技术、分子模拟技术、X-晶体衍射技术等，将实验手段和量子化学分析手段相结合，解析水分子在环糊精-淀粉体系的迁移和分布导致淀粉有序化过程中晶体变化规律和机制，为淀粉抗回生机理探索提供新的思路，对于促进淀粉深加工产品品质具有重要意义。

项目通过开发γ-CGTase 、4aGTase等关键催化用酶，探索了母体环糊精、分支环糊精及大环糊精的制备、分离、检测方法，并探索不同环糊精抗淀粉回生过程，围绕环糊精抗淀粉回生的机理、水分迁移和分布规律、环糊精-淀粉体系的再利用等方面开展了系列研究，取得创新性研究成果如下：发现β-CD能够同时发挥对小麦淀粉的短期回生抑制作用和长期回生抑制作用，且β-CD抗小麦淀粉回生受水分含量影响显著；发现在混合体系中β-CD的添加增强了淀粉体系的氢键作用力，环糊精空腔的疏水性促进了体系的水分迁移；通过对环糊精的空腔疏水性进行测定、环糊精空腔疏水性变化进行分子模拟计算，发现环糊精促进淀粉回生过程中的水分迁移的主要驱动力是环糊精空腔疏水作用力，且该作用力是环糊精与淀粉形成复合物的关键驱动力之一；利用该特性，用反溶剂法制备出一种廉价易得且工艺简单的纳米材料。该研究完善了β-CD抗淀粉回生的作用机制，为拓展β-CD的工业化应用、解决工业上普遍存在的淀粉回生问题提供了参考。