Physicochemical, thermal and pasting characteristics of gamma irradiated rice starches

• Rice starches isolated from two recently released varieties were gamma irradiated at 0, 2, 5 and 10 kGy.
• Irradiation significantly reduced amylose content, pH and swelling index.
• Pasting properties and retrogradation enthalpy decreased significantly with irradiation.
• Particle size reduced with formation of small size granules.

Starches isolated from two recently released rice cultivars (PR 121 and PR 116) grown in sub-tropical climates of Punjab, India were subjected to gamma irradiation at 0, 2, and 10 kGy doses using a Co60 irradiator source. Physicochemical, thermal, pasting, and morphological properties were studied. Irradiation resulted in a significant decrease in apparent amylose content, swelling power and pasting properties. Carboxyl content and solubility increased with irradiation. The granule morphology was evaluated using scanning electron microscope, particle size analyzer and light microscope. Irradiation resulted in formation of small size granules. Granules were irregular and polyhedral in shape. The granule morphology and A-type X-ray diffraction pattern were not altered by irradiation.