Effect of gamma irradiation on the physicochemical and morphological properties of starch extracted from lotus stem harvested from Dal lake of Jammu and Kashmir, India

Starch isolated from lotus stem was treated by gamma-irradiation at different doses of 5, 10 and 20 kGy. Physicochemical, morphological and pasting properties of irradiated lotus stem starches were investigated and these properties differed significantly. Carboxyl content, water absorption capacity, amylose leaching, and transmittance increased, whereas swelling power, apparent amylose content, syneresis, and pasting properties decreased after the modification in a dose dependent manner. Observation under scanning electron microscope (SEM) showed that some of the starch granules were destroyed by gamma-irradiation and the breakage was much greater at a higher dose (20 kGy). X-ray diffraction pattern remained the same upon irradiation but a dose dependent decrease in relative crystallinity was observed.