可溶性膳食纤维对淀粉水解和葡萄糖扩散的调控机制研究

Soluble dietary fiber has a significant effect on the digestion of starch and absorption of glucose in gastrointestinal tract (GIT), which is very important for the human health. However, the exact mechanism(s) by which dietary fibers are able to modulate the rate of starch hydrolysis and glucose diffusion remains to be elucidated. This proposal try to study the interaction between soluble dietary fiber (β-glucan, KGM and xanthan gum) and starch in simulated GIT solution by light scattering and rheometer techniques combined with the diluted solution theory and concentrated solution properties. Further work is to establish the simulated digestion model in vitro to evaluate the effects of dietary fiber on the hydrolysis of starch and diffusion of glucose as well as the kinetics model based on the rheological properties. The relationship between in vitro digestion and solution properties is going to be found out. Tha aim of the proposal is to elucidate the mechanism of dietary fiber effect on the the hydrolysis of starch and diffusion of glucose in simulated GIT solution. This proposal will present the mechanism of dietary fiber to exert the physiological functions on molecular level. The results will provide a theoretical foundation for the selection of good quality dietary fiber as well as the popularisation of dietary fiber used in the human diet in our country.

可溶性膳食纤维可有效调节胃肠道环境中淀粉的水解消化和葡萄糖的吸收速率，对人体健康起着积极的作用，然而，关于膳食纤维对淀粉水解和葡萄糖扩散的调控机制还不清楚。本项目拟通过光散射和流变技术，结合高分子稀溶液理论与浓溶液性质，探讨可溶性膳食纤维（β-葡聚糖、魔芋多糖和黄原胶）与淀粉在模拟胃肠道溶液中的相互作用；在此基础上，构建体外模拟消化吸收模型，基于流变特性研究膳食纤维对淀粉水解和葡萄糖扩散的影响及其动力学分析，建立体外消化吸收与溶液性质之间的关系，最终结合膳食纤维与淀粉的相互作用阐明其对淀粉水解和葡萄糖扩散的调控机制。本研究将从分子水平探讨膳食纤维发挥生理功能的作用机理，为探寻优质膳食纤维资源，推广膳食纤维在我国居民饮食中的应用奠定理论基础。

可溶性膳食纤维（SDF）可有效调节人体淀粉消化和葡萄糖吸收速率，对降低食物血糖响应和餐后血糖水平起着积极的作用。为阐明SDF调控淀粉消化吸收的作用机理，本项目选取β-葡聚糖类、木葡聚糖类、酸性多糖和葡甘聚糖类等四大类SDF为研究对象，首先对不同SDF的结构和溶液构象进行表征，通过粘度仪、扫描电镜、低场核磁共振以及流变等技术，研究了不同膳食纤维与淀粉的相互作用，在此基础上，构建体外模拟消化吸收模型，研究了SDF对淀粉消化和葡萄糖扩散的影响，建立了淀粉消化动力学与消化液粘度衰减之间的关系。结果表明：SDF可改变玉米淀粉的糊化性质，与淀粉分子竞争结合水，降低混合体系的水自由度，提高体系的表观粘度。体外模拟表明消化液表观粘度是影响淀粉消化和葡萄糖扩散的主要因素，粘度越大，消化液的流动性越低，从而阻碍消化产物的释放，并由此抑制酶与底物的反应速率，降低淀粉的消化和吸收速率；不同SDF可通过缠绕、包裹以及SDF自身聚集等方式提高体系表观黏度，达到抑制淀粉消化和葡萄糖扩散的作用。动力学模型表明SDF可通过调节消化液粘度的衰减速率，来调控淀粉早期消化阶段的消化速率，粘度水平越高，延缓效果越好，且不同SDF由于结构差异，其与淀粉交联和缠绕作用能力不同，在对消化液粘度衰减速率上表现出显著差异，这对开发SDF延缓淀粉的快速消化和避免血糖在短时间内迅速升高具有重要意义。本研究为SDF在降低食物血糖响应和餐后血糖水平方面提供更深入的证据，为糖尿病人饮食管理、SDF在淀粉类食品中的应用及低GI食物的开发利用提供理论依据，同时也可为探寻优质膳食纤维资源，推广膳食纤维在我国居民饮食中的应用奠定理论基础。