淀粉中间级分的分子结构及其构造单元骨架模型的探究

淀粉是植物能量储存的基本形式，作为人类日常生活的重要营养来源及食物的重要原辅料而备受关注。它主要由高度分支的支链淀粉和近似线性的直链淀粉组成，直支比及其分子特性决定了淀粉的结晶结构、功能特性乃至淀粉质产品的性能。前期研究指出，某些淀粉(尤其是高直链)存在结构特性介于直链淀粉和支链淀粉之间的第三种组分，即中间级分。为全面理解淀粉的结构功能，应准确表征三种不同淀粉组分的结构特征。然而，中间级分的精细结构及其对淀粉结构和性质的影响尚不明确。因此，本课题拟以典型的玉米、豌豆、马铃薯为研究对象，采用正丁醇-异戊醇选择沉淀法分离提取淀粉的3个级分，对比分析三者在精细结构上的差异以此揭示中间级分的结构本质，并根据分子结构参数构建其构造单元结构模型；探讨不同来源淀粉的结构与性质差异以期全面理解中间级分在淀粉颗粒结构中存在形式及组织排列，探讨其对淀粉结构与功能特性的贡献；旨在完善淀粉结构与功能的基础理论。

As the principal energy reserve material in plants, starch attracts considerable attention as the most important nutrition source for human consumption and the significant ingredient for food. There are two major starch fractions, i.e., highly branched amylopectin (AP), predominantly linear amylose (AM). The AM/AP ratio and their molecular features have been confirmed crucial in determine the semicrystalline structure of starch and also its functional properties and even the performance of starch-based products. Previous studies indicated that a third starch fraction has been proposed for especially amylose-extender (ae) mutant starches, which is termed as the intermediate material (IM) of starch with structural features different from both amylose and amylopectin. To comprehensively understand the structural features and functionalities of starch, the structural features of different starch fractions, not only amylopectin and amylose but also IM, should be accurately evaluated. However, the fine structure of the IM and its effects on structure and properties of starch were not clear. Therefore, the three starch fractions, i.e., amylopectin, intermediate material, and amylose from typical cereals starches, beans starches and tubers starches will be obtained using differential alcohol precipitation using n-butanol and isoamyl alcohol in the present study. Then we will investigate the differences in the fine structure of intermediate material and amylose and amylopectin to reveal the structural nature of intermediate material. Furthermore, the building block backbone model of the intermediate materials will be constructed based on their molecular structure parameters. The differences between the structure and the properties of starch from different sources will be discussed, so as to reveal the existing form of IM in the starch granules structure and their organization in particle structure, and to comprehensively understand the contribution of intermediate fractions to starch structure and functional characteristics, and improving the basic theory of starch structure and function.