Cosolvent effect of ethanol on the solubility of lutein in supercritical carbon dioxide

Abstract

This contribution presents new high-pressure solubility data of solid trans-lutein in pure carbon dioxide (CO2), and mixtures of CO2 and ethanol. The cosolvent effect of ethanol was determined by comparing lutein solubility between the ternary (CO2 + ethanol + lutein) and binary (CO2 + lutein) systems at (313, 323, and 333) K and from (18.70 to 33.55) MPa. 92% pure lutein was isolated from marigold flower petals. Solubility was measured using a dynamic-analytical method with recirculation and online analysis of the CO2-rich phase. The solubility of lutein in pure and ethanol-modified CO2 increased with system temperature and pressure. Solubilities in pure CO2 ranged from 0.82 10−6 mol mol−1 at (313 K and 18.70 MPa) to 2.45 10−6 mol mol−1 at (333 K and 32.91 MPa). The highest solubility of lutein in CO2 experimentally measured was 4.02 10−6 mol mol−1 at (333 K and 32.91 MPa) when adding 0.0211 mol mol−1 of ethanol.