Modifications of structure and physicochemical properties of maize starch by γ-irradiation treatments

Maize starch powder was exposed to a 60Co source (0, 1, 2, 5, 10, 20, 50, 100, 200, or 500 kGy) and the effects of γ-irradiation treatment on the structure and physicochemical properties of the starch granules were studied. The results showed that peak, trough, final, and setback viscosities were significantly reduced, whereas the solubility was increased following irradiation. Gelatinization temperature and enthalpy decreased significantly when the dose is higher than 50 kGy. On the surface, the starch granules did not display any visible physical change up to a 500 kGy dose was. X-ray diffraction (XRD) analysis showed that the relative crystallinity of starch decreased slightly, and the starch exhibited an A-pattern without any change. Fourier transform infrared (FTIR) spectral intensity at 1018 cm−1 increased with the irradiation dose up to 200 kGy. Irradiation dose was positively correlated with solubility and negatively correlated with relative crystallinity. There were high positive correlations between thermal properties and pasting properties.

► The physicochemical properties of maize starch was modified by gamma irradiation treatment to improve their solubility, shear and thermal resistance for food and non-food applications. ► The structure and physicochemical properties of maize starch were greatly affected by the intensity of gamma irradiation. ► Irradiation dose was positively correlated with solubility but negatively with relative crystallinity, thermal properties, and pasting properties of the maize starches.