Effect of shearing on functional properties of starches isolated from Indian kidney beans

Starches suspensions from four kidney bean lines (varying in amylose content) were sheared for different intervals (0-8 min) at 15 000 rpm at 25 degrees C. Starches were then evaluated for granule size distribution, thermal, rheological, and structural properties. Shearing caused an increase in amylose content, paste viscosities, and small size granules containing granular fragments. Transition gelatinization temperatures: Onset temperature (T-o), peak temperature (T-p), conclusion temperature (T-c), crystallinity, and short-order range decreased upon shearing. Native starches from different lines showed unimodal and trimodal granules distribution. A change in size distribution from trimodal to unimodal was observed in starch upon shearing, starch with higher amylose content showed greater effects. Shearing of starches caused disintegration and fragmentations of granules that made them to gelatinize at lower temperature.