Effects of gamma radiation on the physicochemical properties of brown rice and changes in the quality of porridge

The physicochemical properties and changes in quality of brown rice porridge made with waxy and non-waxy brown rice following gamma radiation were evaluated. The radiation dose applied to the samples was 5 and 10 kGy. The water, ash, and protein contents of non-waxy brown rice (NWBR) and waxy brown rice (WBR) were not influenced by exposure to 5 or 10 kGy gamma radiation. The total starch and resistant starch contents of NWBR and WBR were not significantly altered after gamma radiation. The water-holding capacities of NWBR (105.75%) and WBR (124.10%) exposed to 5 kGy or 10 kGy of gamma radiation were significantly higher than those of the control. Gamma radiation also decreased the pasting properties, such as the peak, final, and setback viscosities, of both types of brown rice. The hardness of brown rice grain was decreased by gamma radiation exposure. The lightness of porridge made from irradiated brown rice was not different (P > 0.05). The viscosity of brown rice porridge exposed to 5 kGy irradiation was lower that of the control or 10 kGy-irradiated samples, and showed similar trends during storage. Thus, gamma radiation of brown rice may have applications in the production of food products such as porridge for infants or elderly people and in delaying the retrogradation of brown rice starch.