Supercritical CO2 extracts from Acacia dealbata flowers

Abstract Supercritical CO2 was used for the production of extracts from Acacia dealbata flowers. Pressures from 10 to 35 MPa and temperatures from 35 to 55 °C were studied to assess their influence on the yield, antiradical properties and composition of the volatiles. The use of ethanol as modifier was also evaluated. Operating at 30 MPa and 45 °C with 10% ethanol, up to 15% of the ethanol extractables were obtained in 3 h. The selectivity towards alcohol type compounds decreased with time and was enhanced in a sequence of static extraction with pure and ethanol modified CO2 followed by a dynamic stage. The most active fractions showed ABTS radical scavenging activity of 0.22 g Trolox/g extract. Different mathematical models were used to describe the kinetic data. The most abundant compounds in the supercritical extracts were oxygenated triterpenes whereas in conventional ethanolic extracts the main constituents were aliphatic compounds.