Physicochemical properties of hydroxypropylated and cross-linked rice starches differential in amylose content.

Hydroxypropylation and cross-linking were carried out on three rice starches with 6.93%, 19.02% and 48.41% AAC respectively. AAC affected the efficiency of modification, with AAC increased, the molar substitution of hydroxypropylated starch decreased while degree of substitution of cross-linked starch increased. Modifications decreased starch relative crystallinity while the impacts were dependent on rice varieties. Starch granules of high AAC rice were liable to be disrupted by modification. High AAC rice starch had better processability, modifications have more pronounced influences on starch properties of high AAC. Different modifications showed different influences on starch properties, cross-linking decreased AAC content, pasting clarity and swelling power of all three starches, while hydroxypropylation increased pasting clarity and swelling power of high AAC starch. High-degree modifications decreased starch digestibility, higher-CLD crosslinked starch showed constant digestion rate and might be a suitable modification for produce starchy food for equilibrium glucose level.