储藏时间对大米淀粉精细结构的影响

In order to systematically investigate starch fine structure of rice during storage, five rice cultivars (collected from different regions) were stored at 35℃ and relative humidity 75% for 30, 60 and 90 d. After rice starch extraction, microstructure, particle size distribution, crystal structure, short-range ordered structure and amylopectin chain length distributions were measured. The results showed that no clear differences displayed on the surface and particle size of rice starch during storage; relative crystallinity of rice starch presented an increasing tendency to different degrees; rice starch displayed typical A-type crystallization and there was no transformation during storage; short-ranged ordered structure of rice starch became tighter and more ordered; the percentage of short amylopectin chains (DP 6-12 and DP 13-24) increased, while the medium and long amylopectin chains (DP 25-36 and DP ≥37) decreased over time.