高粱自然发酵对淀粉分子结构及老化性质的影响

Effect of Natural Fermentation on Molecular Structure and Retrogradation Properties of Sorghum Starch

为明确自然发酵对高粱淀粉分子结构及老化性质的影响,将高粱进行自然发酵,利用碱提法提取高粱淀粉,研究发酵过程中淀粉颗粒表面形态、官能团、淀粉分子质量、链长分布的变化对淀粉老化性质的影响。结果表明:自然发酵后高粱淀粉颗粒表面有一定的侵蚀痕迹;发酵处理未生成新的化学基团,各官能团的峰位保持不变;发酵后淀粉的重均分子质量降低,低分子质量淀粉由74.2%增加到78.5%,同时高分子质量淀粉含量由5.4%降低至2.5%;支链淀粉的短支链百分含量降低1.8%~3.89%,长支链百分含量增加2.01%;发酵后淀粉的峰值黏度及回生值增加,其中回生值增加466 mPa s,使发酵后的高粱淀粉更易形成凝沉,研究结果为自然发酵高粱技术调控及老化淀粉食品加工提供理论基础与数据支持。

This study aimed to clarify the influence of natural fermentation on the molecular structure and retrogradation properties of sorghum starch. The surface morphology, functional groups, molecular mass and chain length distribution of starch prepared by alkaline extraction of naturally fermented sorghum were measured versus fermentation time. The results showed that after natural fermentation, the surface of sorghum starch granules exhibited some traces of erosion;no new chemical groups were formed during the fermentation process, and the peak position of each functional group remained unchanged. The weight average molecular mass of the starch was reduced after fermentation, and the percentage of lowmolecular-mass starch was increased from 74.2% to 78.5%, while the percentage of high-molecular-mass starch decreased from 5.4% to 2.5%;the percentage of short-chain branch of amylopectin decreased by 1.8%–3.89%, whereas the percentage of long-chain branch increased by 2.01%. After fermentation, and the setback value increased by 466 mPa·s, and the peak viscosity also increased. Fermented sorghum starch was more likely to form gel. The findings of this study provide a theoretical basis and supporting data for the regulation of natural fermentation of sorghum and the processing of foods with retrogradated starch.