The effects of operating pressures and temperatures on the solubilities of acylglycerols and free fatty acids (FFA) of palm oil (Elaeis guineensis) in supercritical carbon dioxide (SC-CO2) were determined using a dynamic (flow-through) supercritical fluid extraction system. The solubility of palm oil was also investigated. The experiments were carried out in a 3 X 3 factorial design with three equally spaced pressures (14, 22 and 30 MPa) and three equally spaced temperatures (40, 60 and 80°C). The solubilities (mg/g CO2) of acylglycerols and FFA followed this order: TAG > FFA > DAG > MAG for high pressure. However, highest solubility of FFA was observed at low pressure. The results showed that the solubility of palm oil in SC-CO2 was in the range of 0.1751 ± 0.0007 to 6.60 ± 0.03 mg/g for the conditions studied. The solubility of palm oil in SC-CO2 is significantly influenced by the solubilities of acylglycerols and FFA. The optimum condition for maximum solubility of palm oil was found to be at 60°C and 30 MPa. The experimental data obtained for the palm oil solubility was compared with other vegetable oils and correlated by the improved density-based equation proposed by del Valle-Aguilera.
Solubility of red palm oil in supercritical carbon dioxide: Measurement and modelling