小麦不溶性膳食纤维抑制淀粉消化的机理研究

As an important component of whole grain foods, insoluble dietary fiber is critical for reducing glucose index and maintaining stable blood sugar. However, its mechanism of influencing starch digestion is not yet clear. This project aims to investigate the inhibition mechanism of insoluble dietary fiber for starch digestion. Hard wheat, which is commonly used for producing Chinese traditional staple food, will be used as the raw material, and cellulose and arabinoxylan will be used as models of insoluble dietary fiber. In vitro digestion and first order kinetics will be applied to evaluate starch digestibility, and changes in the morphology and structure of starch during starch digestion in presence of insoluble dietary fiber will also be analyzed to study the influences of insoluble dietary fiber on starch digestion rate and extent. The inhibition type and ability of insoluble dietary fiber for α-amylase will be evaluated through half maximal inhibitory concentration and inhibition kinetics, and the binding sites and enzyme activity will also be analyzed. The mechanism of insoluble dietary fiber for inhibiting α-amylase activity will then be elucidated. Wheat cell wall and wheat bran will also be used to verify the obtained results, and to finally reveal the mechanisms of wheat insoluble dietary fiber for regulating starch digestibility. The outcomes of this project will provide theoretical support for the appropriate processing of bulk grain and for precise design of low GI healthy foods.

不溶性膳食纤维作为全谷物食品的重要组分，对降低血糖生成指数和维持人体血糖稳态至关重要，但其对淀粉消化性的影响机制尚不清楚。本项目针对不溶性膳食纤维对淀粉消化的抑制机理这一基础理论问题，以我国传统主食原料硬质小麦为研究对象，将其中富含的纤维素和阿拉伯木聚糖作为研究不溶性膳食纤维的切入点，通过体外模拟和一级酶动力学方程评价淀粉消化性，跟踪消化过程中淀粉形貌和多层级结构变化，考察不溶性膳食纤维对淀粉消化速率和消化程度的影响规律。通过半抑制常数和酶抑制动力学研究不溶性膳食纤维抑制α-淀粉酶的能力和类型，并测定体系中淀粉酶的结合位点和结合率，阐释小麦不溶性膳食纤维对α-淀粉酶的抑制机理。将所得结果在小麦细胞壁和麸皮两个富含不溶性膳食纤维的全谷物食品配料中进行验证，揭示小麦不溶性膳食纤维抑制淀粉消化的内在机制。研究结果对大宗粮食的科学加工、低GI健康食品的精准设计具有重要的理论指导意义。

不溶性膳食纤维作为全谷物食品的重要组分，对降低血糖生成指数和维持人体血糖稳态至关重要，但其对淀粉消化性的影响机制尚不清楚。本项目针对不溶性膳食纤维对淀粉消化的抑制机理这一基础理论问题，以我国传统主食原料硬质小麦为对象，通过体外模拟、一级酶动力学对淀粉消化性进行评价，结合LOS拟合等多种分析手段，研究不溶性膳食纤维对淀粉消化和理化性质的影响规律。通过酶抑制动力学、多光谱分析等方法，研究不溶性膳食纤维对淀粉消化的抑制机理，以期为低血糖生成指数健康食品的设计制造提供理论指导。具体研究内容包括：（1）小麦不溶性膳食纤维对淀粉消化及理化性质的影响规律；（2）小麦不溶性膳食纤维对α-淀粉酶的抑制动力学；（3）小麦不溶性膳食纤维与α-淀粉酶的相互作用及抑制淀粉消化的机理，并在小麦全粉体系中讨论影响淀粉消化的因素。研究结果发现：（1）在淀粉中加入小麦不溶性膳食纤维可增加体系黏度，影响α-淀粉酶对淀粉的可及度，从而在一定程度上降低淀粉消化速率和消化程度，这与不溶性膳食纤维的添加量有关；（2）小麦不溶性膳食纤维对α-淀粉酶的活性有明显的抑制作用，抑制类型为可逆的混合型抑制，抑制效果与不溶性膳食纤维的浓度呈正相关；（3）小麦不溶性膳食纤维可与α-淀粉酶形成自发的疏水相互作用，结合位点为1，这引起α-淀粉酶二级结构的变化，导致α-淀粉酶活力降低，从而降低淀粉的消化性。项目总体按原计划进行，完成了研究目标和预期成果。原计划发表SCI论文3-4篇，培养研究生3名。最终在项目的资助下共发表SCI论文5篇，中文核心论文1篇，培养研究生4名，项目成果已产生一定的学术价值。本项目为基础理论研究，暂未产生应用价值，项目研究成果将为淀粉消化性能的调控及糖尿病人特膳食品的制造提供理论依据。