Separation of astaxanthin from red yeast Phaffia rhodozyma by supercritical carbon dioxide extraction

The supercritical fluid extraction (SFE) behavior was investigated to extract astaxanthin from the red yeast Phaffia rhodozyma, which was disrupted and dried by bead mill and spray dryer, respectively. The effects of extraction pressure (102-500 bar), temperature (40, 60 and 80 °C), CO₂ flow rate (superficial velocities of 0.27 and 0.54 cm/min) and the use of ethyl alcohol as a modifier (1, 5, 10, 15 vol.%) on the extraction efficiency were determined. The highest yield of carotenoids and astaxanthin with equal amounts of CO₂ (50 g) was 84 and 90%, respectively, at 40 °C and 500 bar. Using a two-step pressure gradient operation, on changing the pressure from 300 to 500 bar, the concentration of astaxanthin in the second fraction at 500 bar increased by about 4 and 10 times at 40 and 60 °C, respectively, and the concentration of carotenoids increased by about 3.6 times at 40 °C and 13 times at 60 °C with the yield decreasing by about 40-50%.