超高压致莲子直链淀粉-脂肪酸复合物形成机理及抗消化特性的研究

The digestion characteristic of starch is of particular importance for human nutrition and health. The formation of amylose-lipid complexes can reduce starch digestibility and can be used as controlled lipid release agents. Previous studies have found that, a small amount of lipid in lotus seed starch interacted with amylose to form complexes during starch gelatinization induced by ultra-high pressure treatment, however, the formation mechanism and digestion resistibility of the complexes have not been understood. Based on this, this project aims to simulate the formation process of lotus seed amylose-fatty acid complexes, in order to investigated the formation mechanism and digestion resistibility of the complexes induced by different ultra-high pressure treatment. Modern analytical instruments will be used to investigate a variety of multi-scale structures (particle structure, aggregation state structure, short-range structure and molecular chain structure), the thermal and pasting properties of the complexes. The preparation conditions of complexes and the change rule of digestion resistibility and multi-scale structures of lotus seed amylose-fatty acid complexes treated by ultra-high pressure will be clarified and explained. The formation mechanism and digestion resistibility of the complexes would be revealed. The outcome of this project is beneficial to expand the application field of ultra-high pressure technology in starch modification, and provide an important theoretical guidance to regulate the healthy starch in starchy foods such as lotus seed.

淀粉的消化特性对于人类的营养和健康至关重要，直链淀粉-脂质复合物的形成能够降低淀粉的消化性，可作为脂质控释剂。前期研究发现，莲子淀粉中存在的少量脂质在超高压导致的淀粉糊化过程中与直链淀粉相互作用形成复合物，但其形成机理及抗消化特性尚未知。基于此，本项目拟模拟莲子直链淀粉-脂肪酸复合物的形成过程，研究不同超高压制备条件下复合物的形成机理及抗消化特性。采用现代分析仪器对复合物的颗粒结构、聚集态结构、短程结构、分子链结构等多个尺度结构以及热特性和糊化特性进行系统研究。阐明复合物的超高压制备条件以及超高压处理后莲子直链淀粉-脂肪酸复合物的抗消化特性与不同尺度结构的变化规律，揭示超高压条件下莲子直链淀粉-脂肪酸复合物的形成机理及抗消化特性。本项目的研究有利于拓展超高压技术在淀粉改性领域中的应用，为莲子等淀粉类食品中营养淀粉含量的调控起到重要的理论指导作用。

直链淀粉-脂肪酸复合物被称为第五类抗性淀粉，其对于维持餐后血糖稳定，促进肠道健康具有重要意义。本项目采用非热力高新技术——超高压技术制备莲子直链淀粉-脂肪酸复合物，探讨了不同饱和度和不同碳链长度的脂肪酸对复合物形成机理及理化特性的影响，并研究了复合物的多尺度结构、热特性以及抗消化特性。本研究有利于拓展超高压技术在淀粉非热力改性领域中的应用，为莲子等淀粉类食品中营养淀粉含量的调控起到重要的理论指导作用。主要研究结论如下：.（1）莲子直链淀粉-脂肪酸复合物的制备及其分子特性的研究.莲子直链淀粉及复合物的分子量随超高压处理压力的升高而降低。莲子直链淀粉-不同链长脂肪酸复合物的复合指数与脂肪酸碳链长度相关，链长越短其复合指数越高；莲子直链淀粉-不同饱和度脂肪酸复合物的复合指数与脂肪酸饱和程度及分散性相关，复合指数随超高压处理压力的升高而降低。.（2）莲子直链淀粉-脂肪酸复合物结构特性的研究.莲子直链淀粉经超高压处理后为B-型晶型，而莲子直链淀粉-脂肪酸复合物为V6III-型。复合物的形成提高了莲子直链淀粉的结晶度，结晶程度与脂肪酸链长、饱和程度及分散性相关。莲子直链淀粉和莲子直链淀粉-脂肪酸复合物都存在片状结晶结构，复合物的片状结构堆叠为亚微米级球晶，且复合物的形成提高了莲子直链淀粉的质量分型维数。.（3）莲子直链淀粉-脂肪酸复合物热力学特性的研究.莲子直链淀粉与不同链长、不同饱和度的脂肪酸复合后的复合物都属于热力学I型复合物。脂肪酸的碳链长度、饱和程度及分散性影响了复合物的结晶结构，进而影响了糊化特性。.（4）莲子直链淀粉-脂肪酸复合物抗消化特性的研究.莲子直链淀粉-脂肪酸复合物的形成增加了抗性淀粉的含量并降低了易消化淀粉和慢消化淀粉的含量。对莲子直链淀粉-脂肪酸复合物消化率曲线拟合的研究结果表明，莲子直链淀粉与复合物具有近似的消化模式，表明两者都存在螺旋状晶体结构。