Extraction of β-carotene and lipids from wet biomass of the oleaginous yeast Rhodosporidium toruloides with supercritical CO2

The present study investigated supercritical CO 2 extraction (SCE) of β-carotene and lipids from wet biomass of the oleaginous yeast Rhodosporidium toruloides to assess its potential as a green and energy-effective extraction process. The influence of the water content of the biomass on the extraction kinetics was investigated by performing SCE with biomass with different water contents (80.3 wt%, 40 wt%, and 3 wt%). The CO 2 flowrate was set to 0.240 g s −1 . Despite an initial delay in the extraction process, the extraction yields from wet and dried biomass after 195 min (50 °C and 250 bar) showed no significant difference, confirming that an energy-intensive drying step before extraction can be avoided. The effects of temperature (40 °C - 70 °C) and pressure (200 bar - 400 bar) on extraction kinetics were systematically studied. Ethanol as a co-solvent significantly improved extraction efficiency, increasing β-carotene yield (up to 77 %) and lipid yield (up to 49 %). Yeast intracellular lipids were proven to act as an effective natural co-solvent for β-carotene extraction, as evidenced by the significant improvement in β-carotene recovery by 63 % when 10 wt% sunflower oil was added to the wet biomass as a co-solvent. The fatty acid methyl esters (FAME) analyses showed that the extraction conditions did not influence the FAME composition. The obtained extracts exhibited notable antioxidant activity, with an IC 50 of approximately 2 mg mL −1 , highlighting the potential of the oleaginous yeast Rhodosporidium toruloides as a valuable source for applications in functional foods and pharmaceutical products. • Extraction yields from wet and dry biomass showed no significant difference. • Ethanol as a co-solvent increased total and ß-carotene yields. • Biomass lipids acted as a natural co-solvents during ß-carotene extraction. • Biomass water content did not influence the antioxidant activities of the extracts.