Morphological and Rheological Properties of Starches Separated from Cultivars of Rice (Oryza sativa L.) from North East India

摘要

Starch granules isolated from different accessions of rice from North East India showed a typical polygonal morphology with size ranging from 3.4 ± 0.8 μm to 6.4 ± 1.2 μm. The apparent amylose content (AAC) of the granules varied from 1.9% to 28.33%. Our results identify starch from IC-583088 as “waxy” and IC-583085, IC-583038, DPRR-168 as “very low” amylo-. The coefficient of resistance to flow (n) for starch pastes from the varieties of rice studied in the present investigation recorded a value of <1.0. The observed “n” value deviates from the Newtonian flow indicating the pseudoplastic nature of starches isolated from these varieties. While starch pastes from the accession IC-583088 recorded the highest ‘‘n’’ value of 0.6, that from the accession IC-545197 showed the lowest value of 0.03. The variations in coefficient of resistance to flow clearly revealed a higher ‘‘n’’ value for starch pastes from the “waxy” and ‘‘low” amylo-cultivars than the “intermediate” or ‘‘high” amylo-cultivars. Our results clearly established characteristic rheological properties for starches from the accessions SKY-AK-1608, IC-583035, YS-RC-219, IC-564939 and IC-332963, which exhibited greater resistance to thinning and shearing than other varieties.