New developments in the modelling of carotenoids extraction from microalgae with supercritical CO2

Literature data on the extraction of carotenoids from microalgae with supercritical carbon dioxide (scCO(2)) were used to describe the process as an extraction of a solution of carotenoids in oil. A mathematical model for oil extraction from microalgae, including also the adsorption on microalgal surfaces, was extended for this purpose. The working hypothesis was that the extraction process is primarily controlled by phase equilibrium where the solubility of carotenoids in scCO(2), as minor components, depends on the solubility of the major component - microalgal triglycerides. The above assumption was supported and confirmed by the results of the modelling of the vapor-liquid phase equilibria of the system carotenoid + oil + scCO(2), which was performed applying the predictive Soave-Redlich-Kwong cubic equation of state. The well-known increase of extraction rate and yield with extraction pressure and temperature was shown to be a result of both increasing carotenoid solubility in scCO(2) and decreasing adsorption capacity of microalga.