Physicochemical and structural characteristics of rice starch modified by irradiation

This work evaluated the physicochemical and structural properties of rice starch of the cultivars IAC 202 and IRGA 417 modified by irradiation. Starch samples were irradiated by 60Co in doses 1, 2 and 5 kGy, on a rate of 0.4 kGy/h. A control not irradiated was used for comparison. The granule morphology and A-type X-ray diffraction pattern were not altered by irradiation. There was an increase in amylose content, carboxyl content and acidity with irradiation. Gamma radiation did not affect the thermal properties of IAC 202, but increased gelatinization temperature of IRGA 417, in the higher dose (5 kGy). The number of long chains of amylopectin was reduced and short chains were increased for IAC 202, whereas for IRGA 417, the opposite was observed, probably due to cross-linking of starch chains. Starches had their physicochemical and structural properties modified by irradiation differently.