湿热处理对不同直链淀粉含量大米淀粉多尺度结构和消化性能的影响

本文采用体外模拟法和现代化分析技术测定及考察了不同直链含量的大米淀粉经湿热处理后其多尺度结构和消化性能的变化情况，明晰了湿热处理后大米淀粉多尺度结构和消化性能的关系。结果表明，湿热处理体系中热能和水分子的协同作用，一方面对大米淀粉颗粒具有一定的破坏作用，使得其平均相对分子量降低、双螺旋含量降低、相对结晶度降低、半结晶片层的有序化程度降低，Mw>2×107的高分子量片段区域逐渐向Mw<1×106拓宽，且直链含量较低的大米淀粉破坏程度更为显著。另一方面，湿热处理促进了降解后的大米淀粉分子链自由运动，使淀粉分子发生重排和取向，形成新的单螺旋结构，有利于大米淀粉慢消化和抗消化性能的提高，且直链淀粉含量较高的大米淀粉提高的越明显。研究结果为加工淀粉及淀粉基营养健康食品提供了基础数据及理论支撑。
In this paper, the relationship between multi-scale structure and digestibility of rice starch with different amylose content before and after the heat-moisture treatment (HMT) was investigated. The results showed that the thermal energy and water molecules during HMT could degrade starch molecules, unravel double helix, reduce relative crystallinity and decrease the ordered degree of lamellar structure, and the Mw>2×107 area gradually turned to the Mw<1×106. And these changes were more obvious with the lower amylose content of rice starch. Accompanying the structural disorder and degradation, some molecule rearrangements and orientation occurred to probably form densely packed starch fractions such as new single helix structure, which was conducive to improve the content of slowly digestible starch (SDS) and resistant starch (RS), and these changes were more obvious with the more amylose content of rice starch. The results provide basic data and theoretical support for the processing of starch and starch-based nutritional healthy food.