Extraction of woolgrease with supercritical carbon dioxide

Supercritical carbon dioxide was used to extract unrefined woolgrease. The resulting product had no color and little odor, resembling high-grade commercial lanolin. The amounts of woolgrease extracted for fixed volumes of supercritical fluid solvent were measured at 60, 70 and 80°C and at pressures from 200–520 bar. In this study, the highest recoveries were obtained at 80°C and pressures in excess of 380 bar. Analysis of the extracts by capillary supercritical-fluid chromatography and thin-layer chromatography indicated that the composition of the extract changed with extraction time. The earliest fractions were enriched in cholesterol and contained relatively small amounts of species with higher molecular weight. The results suggest that supercritical fluid extraction may be used to obtain an enriched cholesterol fraction from wool-grease.