Pilot scale extraction of rice bran oil with dense carbon dioxide

The purpose of this study was to measure the effects of temperature, pressure, and flow rate of dense CO2 on its ability to extract, refine, and fractionate rice bran oil. Column beds (300 g) of rice bran were extracted with dense CO2 at a flow rate of similar to 2.5 kg/h, temperatures of 0-60 degrees C, and pressures of 17-31 MPa over a period of 6 h. The extracted total oil; the free fatty acid, alpha-tocopherol, sterols (campesterol, stigmasterol, beta-sitosterol), and oryzanol components; together with moisture were measured at intervals. Extraction was almost complete in 6 h, and rates of extraction were consistent with saturation of the CO2 with rice bran oil throughout most of the process. Extraction of the oil components was described by apparent partition coefficients between the oil and CO2 phases. The observed differences in partition coefficients provide a basis for refining and fractionation of rice bran oil.