For plant-based lipophilic compounds, extraction is one key
processing step in recovering and purifying them (Liu, 1999). The
choice of a suitable solvent affects mass transport process and subsequent
efficiency of the extraction. The solvent which is most
widely used to extract edible oils from plant is hexane (Serrato,
1981). Recently, the use of alternative solvents including supercritical
carbon dioxide, isopropanol and ethanol has been increasing
for the health and environmental benefits (Dunnuck, 1991). Nevertheless,
alternative solvents often exhibit lower efficiency because
of a decreased molecular affinity between solvent and solute, as
well as the higher cost for solvent and process equipment (Baker
and Sullivan, 1983)