A process for treating defatted rice bran to produce a high value protein product and a cellulosic residue both from defatted rice bran. The high value protein product is useful as a protein supplement or feed for livestock and poultry and the cellulosic residue has value as a feedstock for a thermochemical process unit for the production of a biofuel. The defatted rice bran is subjected to both starch hydrolysis and protein hydrolysis and a resulting liquid stream containing hydrolyzed proteins is sent through a two membrane filtration stages, the first being a microfiltration and the second being a nanofiltration stage.
