Influence of different molar concentrations of acid on morphological, physicochemical and pasting properties of Pakistani Basmati and Irri rice starches.

Starches extracted from two dominant varieties of rice, Basmati and Irri were subjected to acid hydrolysis by preparing starch slurry of 35% (w/v) in HCl solutions of concentrations 0.1M, 0.3M and 0.8M. The scanning electron micrographs showed that granular morphology of starches significantly changed after acid hydrolysis. Acid thinning improved the solubility of starches whereas decline was observed in swelling power and water retention capacity. Paste clarity of both acid treated Basmati and Irri rice starches reduced gradually upon cold storage. Also reduction in values of pasting, peak viscosity, hot paste viscosity, cold paste viscosity and set back were observed in acid thinned Basmati and Irri rice starches. The DE values increased with the increase in HCl concentration for both Basmati and Irri starch. The hardness of 0.8M HCl treated Basmati starch gel was found significantly lower than all treated and untreated starches. The gelatinization enthalpy for Basmati starch significantly reduced after acid hydrolysis with 0.1M, 0.3M and 0.8M HCl solutions at p <0.05.