Process integration of supercritical carbon dioxide extraction and acid treatment for astaxanthin extraction from a vegetative microalga

► A method was developed to extract astaxanthin from a vegetative green microalga. ► A supercritical-CO2 successfully extracted astaxanthin from the microalgal biomass. ► The addition of ethanol as a co-solvent improved extraction yield. ► Chlorophyll was easily separated from astaxanthin by acid treatment.