A study of some physicochemical properties of high-crystalline tapioca starch

Tapioca starch was partially hydrolyzed in hydrochloric acid solution at ro om temperature for various lengths of time to obtain high-crystal line star ches. RVA viscoamylograms of acid-modified starches demonstrated a very low viscosity as compared to that of native tapioca starch. The relative cryst allinity of native and acid-modified tapioca starches were measured by X-ra y diffraction ranging from 39.53% to 57.75%. The native and acid-modified t apioca starches were compressed into tablets using various compression forc es. The % relative crystallinity of starch increased with the increase in h ydrolysis time and the crushing strength of the tablet was also increased i n line with the crystallinity while the amylose content decreased when the crystallinity increased. These results suggested that the erosion of amylos e might cause the rearrangement of starch structure into a new more tightly packed form, which provided the higher crushing strength for the tablets.