Differences in functional properties and biochemical characteristics of congenetic rice proteins

Proteins in brown rice (BR), white rice (WR) and rice bran (RB) were extracted from the same paddy rice and investigated for their components, functional properties and chemical characteristics by SDS-PAGE methodology. BR and WR proteins possessed a poor solubility under weak acid conditions due to a high content of glutenin and richness in higher molecular-weight (MW) protein fractions. Rice bran protein contained significantly lower molecular-weight components (MWs < 50 kDa) than those in WR and BR. Nitrogen solubility, foaming and emulsification properties of their rice protein preparations were affected not only by pH (3-11), but also by the concentrations of NaCl (0.4-2.0%) and sucrose (4.0-20.0%). All of them, particularly rice bran protein, had favorable functional properties in the medium with a high salt or sugar concentration. Therefore, they have a good potential for development in the food industry. (C) 2009 Elsevier Ltd. All rights reserved.