微波诱导淀粉解组装规律变化对胶态淀粉分子聚集态特性的影响机制

With tremendous health benefits, resistant starch has been recognized as one of the most favorable ingredients for healthy foods. Our previous findings have revealed that compared with conventional conduction cooking, microwave cooking can result in gelatinized starch (colloidal form) with higher tendency to form resistant starch during storage. This phenomenon closely relates to the microwave-induced changes in the molecule aggregation features of colloidal starch, e.g., compactness of molecular chain entanglement, and size of molecular chain aggregates. Nonetheless, it is still unclear that how microwave affects starch molecular disassembly and thus alters the molecule aggregation features of colloidal starch. Here, with conventional conduction cooking as a control, from various native starches, we will prepare different colloidal starches with different resistant-starch-forming abilities during storage using varied microwave cooking conditions. Afterward, the starch disassembly (disorganization of multi-level structure, accompanied with evolution of molecular fine structure) during cooking-induced formations of those colloidal starches will be understood, using combined techniques such as temperature-resolved small/wide angle X-ray scattering and high performance anion-exchange chromatography. In addition, the molecule aggregation features of different colloidal starches will be explored, which will allow the establishment of the relationship between the difference in the molecule aggregation features and the changes in the starch molecular disassembly. Based on the above results, the mechanism regarding how microwave-induced evolutions in starch disassembly affect the molecule aggregation features of colloidal starch will be understood, which will provide a theoretical basis for understanding the microwave-enhanced resistant starch formation and thus for producing starch ingredients with desired digestion resistance.

抗消化淀粉因其诸多健康益处而成为备受青睐的健康食品组分。前期发现，相比常规蒸煮，经微波蒸煮糊化的胶态淀粉（溶/凝胶）在贮藏中可形成更多抗消化淀粉，这与微波作用下胶态淀粉分子聚集态特性（链缠绕致密性、链聚集体尺寸等）的变化密切相关，然而微波影响淀粉分子解组装规律从而改变胶态淀粉分子聚集态特性的机制尚不明确。本项目以淀粉为研究对象，以常规蒸煮为对照，通过变换微波蒸煮条件，构建贮藏中抗消化淀粉形成能力不同的胶态淀粉；运用温度分辨同步辐射小角/广角X射线散射、阴离子交换色谱等，考察这些不同胶态淀粉形成过程中淀粉分子解组装的规律（多层次结构无序化模式、分子精细结构演化模式）；明确不同胶态淀粉的分子聚集态特性，建立此类特性差异与淀粉分子解组装规律变化之间的关联，阐明微波诱导的淀粉解组装规律变化对胶态淀粉分子聚集态特性的影响机制，为揭示微波如何强化抗消化淀粉形成及构建抗消化性适宜的淀粉组分奠定理论基础。

合理降低食品中淀粉组分的消化速率对低血糖指数健康食品的研发具有重要意义。前期研究显示，微波加热贮藏可使所制备的胶态淀粉中形成更多的慢/抗消化淀粉。本项目从加热过程中淀粉分子解组装的角度，系统研究了微波作用下淀粉解组装规律及其影响胶态淀粉结构特性和消化特性的机制，为制造消化特性适宜的淀粉类食品及配料提供了理论依据。主要开展了以下三个方面的研究：. 1.选取不同大米淀粉为原料，以常规蒸煮为对照，利用不同微波蒸煮条件（功率、时间、体系水分）制备系列的胶态淀粉，将这些淀粉在特定温度下贮藏不同时间，通过体外消化法测定这些微波处理淀粉的消化特性；进一步变换微波处理条件，制备具有不同消化特性的淀粉试样。2.以上述淀粉试样为研究对象，采用固体核磁共振、温度分辨同步辐射小角/广角X射线散射等，揭示微波加热过程中淀粉的螺旋、结晶、薄层、颗粒等多层次结构的演化，从而揭示微波诱导下淀粉分子的解组装规律及其在不同条件下的差异。3.综合运用多种分析方法，明确贮藏后胶态淀粉结构特性及其在消化过程中的变化情况，归纳分析淀粉分子解组装-胶态淀粉结构特性及其在消化中变化-淀粉慢/抗消化特性之间的关系，阐明微波作用下淀粉分子的解组装规律及其影响胶态淀粉特性和促进慢/抗消化态淀粉形成的机制。. 项目执行期间，发表第一/通讯作者的英文论文10篇；获得第二届中国粮油学会青年科技奖、湖北省科技进步二等奖等科技奖励；入选第四届中国科协青年人才托举工程、湖北省楚天学者计划楚天学子等人才类项目，培养研究生3人（2人在读）、本科生3人；举办中国科协第371次青年科学家论坛暨2019粮油营养与健康青年科学家论坛1次，在学术会议作报告6次。