基于超高压下燕麦米淀粉和β-葡聚糖结构变化及抑制淀粉老化机制

Oat grains, an important special miscellaneous grains, possess the special nutritional value and healthcare functions. However, starch retrogradation of oat grains is one of the reasons for preventing the development of oat instant rice application. Ultra-high pressure treatment can change non-covalent bonds which maintain polymer stereo structure in food materials. In this study, the changes of oat starch chain ratios, molecular weights, microstructures, the contents and structural changes of β-glucan are analyzed after oat grains are treated by ultra-high pressure treatment. Additionally, their effects on retrogradation of oat grains starch, migration and distribution of water molecules during starch retrogradation process are also determined. These results reveal the mechanism of oat grains starch retrogradation inhibition following ultra-high pressure treatment, indicating a new approach to inhibit the retrogradation process of oat grains starch.

燕麦米是重要的特色杂粮，具有特殊的营养价值和保健功能。但燕麦米淀粉容易老化是燕麦大米方便米饭加工应用受限的原因之一。超高压处理使物料中维持高分子立体结构的非共价键发生变化。本研究通过超高压处理燕麦米后，分析燕麦淀粉链支比、分子量及微观结构变化、β-葡聚糖含量和结构变化及其对淀粉老化特性的影响，燕麦米淀粉老化过程中水分子迁移和分布特征，揭示超高压处理抑制燕麦米淀粉老化机制，探索抑制燕麦米淀粉老化的新途径。

燕麦米是重要的特色杂粮，具有特殊的营养价值和保健功能。但燕麦米淀粉容易老化是燕麦米方便米饭加工应用受限的原因之一。超高压处理使物料中维持高分子立体结构的非共价键发生变化。本研究通过超高压处理燕麦米后，分析燕麦淀粉链支比、分子量及微观结构变化、β-葡聚糖含量和结构变化及其对淀粉老化特性的影响，燕麦米淀粉老化过程中水分子迁移和分布特征，揭示超高压处理抑制燕麦米淀粉老化机制，探索抑制燕麦米淀粉老化的新途径。.结果表明：超高压处理对燕麦淀粉微观结构的影响经历结晶完善、结晶破坏、结晶解体和糊化阶段；超高压处理（500MPa处理15min）能够抑制燕麦淀粉、燕麦淀粉/β-葡聚糖复配体系的老化。与燕麦淀粉相比，超高压处理及添加β-葡聚糖后，老化期间，凝胶体系硬度降低，短程有序结构、双螺旋结构减少，相对结晶度降低，老化延缓。.超高压处理增强了燕麦淀粉颗粒内部直链淀粉分子的相互作用，减少了糊化过程中直链淀粉的溶出；β-葡聚糖添加后通过氢键与直链淀粉相互作用，抑制了老化初期直链淀粉相互作用形成晶核的过程，从而使支链淀粉以该晶核为中心形成晶体结构的过程延缓；超高压处理及β-葡聚糖的添加增强了淀粉凝胶体系对水分的束缚作用，导致体系中水分子流动性减弱，减缓了淀粉分子的迁移重结晶速率，从而抑制淀粉的老化。抑制老化的机制为：超高压处理和β-葡聚糖的添加通过延缓老化初期直链淀粉相互作用形成晶核的过程并降低体系老化过程中水分子的流动性和重结晶速率从而抑制燕麦淀粉的老化。