Effects of Ultrasound and Steam Explosion Treatments on the Physicochemical Properties of Rice Bran Fibre

Abstract

Rice bran (RB) is an underutilised fibre source due to undesirable effects when incorporated into food products. Thus, this study aims to improve the physicochemical properties of RB by using ultrasound (US) and steam explosion (SE) treatments, making it more usable in food applications. The US treatment of unpurified RB resulted in inconsistent average particle size, water binding capacity (WBC), and swelling capacity (SC). The bulk density (BD) decreased while the oil binding capacity (OBC) increased as the amplitude and time increased. While the purified rice bran resulted in decreased average particle size and BD; and increased WBC, SC, and OBC. The surface microstructure of the unpurified and purified rice bran became more porous, and the colour of the RB was darkened proportionally to the intensity of US treatment. The average particle size of unpurified increased while the purified RB increased after steam explosion treatment regardless of the intensity. The SE treatment also decreased WBC and SC of unpurified and purified RB, but no changes were observed on the surface microstructure of both samples. The BD of unpurified RB decreased, while the BD of purified RB increased after SE treatment. The SE treatment also resulted in a decrease in the OBC of purified RB, but no significant (p > 0.05) improvement was observed in the OBC of unpurified RB. Ultrasound brought these changes in the two treatments more effectively than steam explosion. The alteration of physicochemical properties of RB by the US and SE treatment in this study will allow it to be more applicable in the formulation of food products.