Ordered structure and thermal property of acid-modified high-amylose rice starch

► Acid initially degraded the amylose, then A chain and short B chain of amylopectin. ► Relative double helix content and crystallinity increased with acid hydrolysis. ► The relative crystallinity estimated from 13C CP/MAS NMR was higher than from XRD. ► The To decreased, while the Tp and Tc increased with increasing hydrolysis time. ► The swelling power decreased while solubility increased after acid hydrolysis.