Quantitative extraction of oil from plant material with supercritical carbon dioxide

Supercritical fluid extraction (SFE) both with CO 2 and CO 2 /hexane has been developed as a method of analysis for lipids in cruciferous oilseed, rapeseed products and lupin. The SFE procedure used for quantitative determination of oil was compared to traditional Soxhlet oil extraction. The quantitative values obtained with SFE were equal to those obtained with the Soxhlet procedure with respect to oil and fat contents. The oil obtained by SFE had a much lower phosphorus content (below 14 mg/kg compared to 200-530 mg/kg in oil obtained with Soxhlet). When adding hexane to the supercritical fluid in concentrations varying from 50 to 150 mL/L CO 2 , the solubility of oil in the fluid could be raised up to 600%, from about 30 mg/g without addition of modifier to nearly 200 mg/g when using continuous addition of 150 mL hexane/ L CO 2 . The phosphorus content was still lower than in oil from Soxhlet (20-64 mg/kg). Therefore, extraction of oil with SFE opens the possibility for selective removal of oil before separate extraction and determination of amphiphilic compounds, e.g. phospholipids. The carotenoid and chlorophyl content in different oils from SFE and Soxhlet were evaluated by UV-VIS determinations. The presence of other amphiphilic compounds was verified and sinapic acid was found to be a quantitatively dominating phenolic compound.