Optimization of the Supercritical CO2 Extraction of Oil from Rapeseed Using Response Surface Methodology

Three operating parameters (pressure, temperature and extraction time) of the supercritical CO2 extraction of oil from rapeseed have been optimised by response surface methodology to obtain high yield of oil. Results showed that data were adequately fitted into the second-order polynomial model. The linear and quadratic terms of independent variables of temperature, pressure and extraction time had a significant effect on the oil yield. Optimal conditions for oil yield within the experimental range of the studied variables were 29.7 MPa, 52.14 °C and 3.36 h, and oil yield was predicted to be 28.27 %. In addition, the mass transfer model was used to describe the extraction kinetic curves of rapeseed oil and very good agreement was found between the observed and predicted values. The fatty acid composition of rapeseed oil extracted by supercritical CO2 at optimal operating parameters and that by n-hexane were analysed by gas chromatography. The obtained oil showed similar fatty acid composition with an unsaturated fatty acid content up to 92.9 %.