Optimization of supercritical carbon dioxide removal of lipid and cholesterol from goat placenta using response surface methodology

Supercritical CO2 (SC-CO2) extraction was applied to remove lipid and cholesterol from freeze-dried goat placenta. A response surface methodology (RSM) was employed to optimize the extraction parameters. The effects of pressure, temperature, flow rate of CO2 and extraction time on the yields of lipid and cholesterol were investigated. Response surface analysis showed that the data were adequately fitted to second-order polynomial model. The independent variables, quadratics of pressure and extraction time, and the interaction between pressure and temperature had significant effects on the yields of lipid and cholesterol, respectively. The optimum parameters within the experimental range of the variables were 34.6 MPa, 35.3 °C, 29.1 min with a CO2 flow rate of 18.2 L/h. Under such condition, the yields of lipid and cholesterol were predicted to be 21.02% and 8.46 mg/g, respectively. Furthermore, the removal efficiency of cholesterol by SC-CO2 was higher than those achieved by Soxhlet and Folch extraction methods.