小扁豆中抗性淀粉的抗热性机理研究

抗性淀粉是一类不被人消化吸收，对健康具有促进作用的新一代膳食纤维。大部分谷物及马铃薯等资源中抗性淀粉含量在经过不同方式的烹调加工后均呈现显著性下降趋势。我们的前期研究发现，小扁豆等杂豆经过湿热处理后，抗性淀粉含量仍保持较高水平，其物理特性与抗性淀粉含量密切相关。小扁豆中抗性淀粉的抗热性是由于在豆壳保护下的热稳定性，还是在湿热条件下豆壳内的淀粉分子在无定形区和结晶区重新排列而形成新的抗性淀粉，目前其机理尚不明确。本项目拟采用X-射线衍射、小角散射、FTIR、13C-NMR、高效排阻色谱等仪器分析，在比较湿热处理前后抗性淀粉的精细结构和构象模型变化的基础上，阐明小扁豆中抗性淀粉的抗热性机理。此外本研究还将结合抗性淀粉低血糖生成指数及黏度、流变等物理性质的测定，进一步探讨小扁豆中抗性淀粉结构与性质的关系。本研究将为小扁豆等杂豆中抗性淀粉的开发与利用提供理论和实验依据，并为科学膳食提供理论指导。

Resistant starch (RS) has been defined as a group of starch that resists digestion in the small intestine of healthy people and is widely recognized as multi-functional and health-promoting ingredient, which has evoked new interests in its uses as a newly developed source of dietary fiber. As indicated in previous studies, the amount of resistant starch derived from most cereal grains, potatoes and other natural resources all showed a significant decrease due to different cooking and processing methods applied. From our preliminary results, it was found that the resistant starch from lentils (Lens culinaris) and other pulses has remained a relative high level after hydrothermal treatment. Additionally, the tendency of the variations in RS content was consistent with those results of the physical properties including thermal properties and the scanning electron microscopy. The assumption needs to be verified whether the heat resistance of RS derived from lentils was related to either its heat stability under the protection of seed hulls, or to the new resistant starch formed by the re-association and re-arrangement of starch molecules from the amorphous and crystalline regions under hydrothermal treatment. By using the techniques of x-ray diffraction, small angle X-ray scattering, Fourier transform infrared spectroscopy (FTIR), 13C nuclear magnetic resonance (13C-NMR), size exclusion HPLC, as well as anion-exchange HPLC, etc., the proposed project is aiming to elucidate the heat resistance mechanisms of RS in lentils, by comparing its molecular and conformational structures before and after hydrothermal treatment. In addition, by analyzing the in vitro glycemic index and physical properties such as viscosity and rheological property of RS, the study also aims to clarify the relationship between the structural characteristics and the hypoglycaemic effects as well as the physical properties of RS in lentils. The goal of the proposed project is to provide theoretical and experimental basis for further application of the resistant starch in pulses, and to provide fundamental guidance in healthy and nutritional diets.