A Simplified Model to Describe the Kinetic Behavior of Supercritical Fluid Extraction from a Rice Bran Oil Byproduct

The mathematical modeling of the overall extraction curve (OEC) was performed using experimental data of supercritical fluid extraction (SFE) from a byproduct of the rice bran oil (RBO) industry. The soapstock derived from the RBO deacidification process was used as raw material because it contains a significant amount of γ-oryzanol, which is a valuable natural antioxidant. The main goal of this work was to describe the OEC by a simplified model using the kinetic data obtained for the SFE from rice bran oil soapstock (RBOS). The global yield isotherms (GYI) were used to select the best operational conditions (temperature and pressure) based on the extraction yield and the γ-oryzanol content of the obtained extract. The OEC was fitted to four simplified models and the kinetic parameters which characterize the constant extraction rate (CER) were estimated. The highest values for the extraction yield (12.5 %, w/w), the γ-oryzanol content (16 %, w/w), and the γ-oryzanol recovery rate (55 %, w/w) were found at 30 MPa/333K. The proposed spline model presented the best fit to experimental data and quantitatively described the OEC. The estimated time span of the CER period (tCER) was 70 min and the corresponding solvent to feed (S/F) ratio and extraction yield were 23 and 9.4 %, respectively.