Solubility of carotenoid pigments (lycopene and astaxanthin) in supercritical carbon dioxide

This contribution provides basic data for developing an extraction process for carotenoid compounds in terrestrial and marine plants with supercritical CO2 (SC-CO2). Specifically, the solubility (y2, molar fraction) of lycopene and astaxanthin was measured in SC-CO2 as a function of temperature (313 K ≤ T ≤ 333 K) and pressure (10 MPa ≤ P ≤ 42 MPa). Experimental data were correlated using a density-based model valid for a solvent density above 330 kg/m3. Based on this model and the best-fit model parameters, the solubility of lycopene in SC-CO2 at 313 K and 30 MPa (y2 = 0.40 × 10−6) was within a wide range of experimental values for the solubility of β-carotene in CO2 under same conditions (0.20 × 10−6 ≤ y2 ≤ 0.50 × 10−6). The interpolated solubility of astaxanthin in SC-CO2 at 313 K and 30 MPa was slightly smaller (y2 = 0.19 × 10−6) than the one of lycopene, as expected for a slightly heavier and more polar solute. There was a larger increase in solubility of both lycopene and astaxanthin by increasing the temperature from 313 to 333 K at a constant pressure of 30 MPa (2.8–5.1 times) than by increasing the pressure from 30 to 50 MPa at a constant temperature of 313 K (1.3–1.6 times), which was consistent with the trend in literature for the solubility of β-carotene in SC-CO2.