Solubility of β-carotene in supercritical CO2 and the effect of entrainers

Solubilities of trans-β-carotene in supercritical CO2, both pure and modified, were measured at temperatures 313.2, 323.2 and 333.2 K and pressures up to 28 MPa using a one-pass flow apparatus. The solubility data measured in pure CO2 were correlated by the density-based equation proposed by Chrastil, and modelled using the Soave-Redlich-Kwong cubic equation of state. Most of the literature data were in good agreement with our results; smaller discrepancies were ascribed mostly to β-carotene degradation. While ethanol entrainer increased the solubility of β-carotene in supercritical CO2 by one order of magnitude, vegetable oil was less efficient. In both cases, the increase in solubility was proportional to square root of entrainer concentration.