Selective precipitation of phenolic compounds from Achillea millefolium L. extracts by supercritical anti-solvent technique

Abstract In this work the fractionation of an ethanolic extract of Achillea millefolium L. (yarrow) using supercritical carbon dioxide anti-solvent technique was studied, with the target of increasing the concentration of phenolic compounds in the precipitated fraction. The effect of pressure on the selective precipitation was analyzed, together with the morphology and particle size distribution of the precipitates. In the range of pressures studied (10–20 MPa), up to a 3 fold increase of the total phenolic compound concentration was observed in the precipitates in comparison with the ethanolic yarrow extract. In addition, the selective fractionation of the main phenolic compounds identified in the extract (3,5-dicaffeoylquinic acid, a glycoside form of apigenin and luteolin, as well as the aglycones) was analyzed. Particle sizes around 250–330 μm were produced with a nozzle of 101.6 μm inner diameter, due to the formation of aggregates. In this respect, increasing pressure from 10 to 15 MPa resulted in smaller particles, while further pressure increasing had no significant effect on particle size decrease.