Supercritical fluid extraction of carotenoids and chlorophylls a, b and c, from a wild strain of Scenedesmus obliquus for use in food processing

Faster and more selective extraction methods are urged to recover food-grade pigments and antioxidants from microalgae - which do not resort to food-incompatible and environment-unfriendly solvents. Hence, this study ascertained the influence of pressure, temperature, CO2 flow rate and a polar co-solvent upon the yields of carotenoids and chlorophylls in supercritical fluid extraction of Scenedesmus obliquus biomass. The highest carotenoid yield was attained at 250 bar and 60 degrees C. The yields of chlorophylls, when using plain CO2, increased slightly with pressure, but decreased with temperature and CO2 flow rate; the highest yield of chlorophyll a was at 4.3 g(CO2), min(-1), whereas ethanol as co-solvent increased all yields except that of chlorophyll c. The highest ratio of total carotenoids to chlorophyll a was reached at 250 bar and 60 degrees C. A remarkable selectivity was observed under these operating conditions, which may enable easy separation and purification of the aforementioned pigments.