Supercritical fluid extraction of carotenoids and chlorophyll a from Nannochloropsis gaditana

Traditional methods for the extraction of carotenoids and chlorophylls from microalgae frequently require more than one extraction step with organic solvents, which are forbidden in the processing of food additives. In addition, further process steps are necessary for the separation of carotenoids from chlorophylls. Consequently, faster processing methods that are compatible with food production are extremely important. The aim of this study was to ascertain the influence of pressure and temperature on the supercritical fluid extraction of carotene and chlorophyll from a freeze-dried powder of the marine microalgae Nannochloropsis gaditana. The operating conditions were as follows: pressures of 100, 200, 300, 400 and 500 bar and temperatures of 40, 50 and 60 degreesC. The extracts were analysed by measuring the absorbance at 665 and 480 nm. Empirical correlations were also developed. The results demonstrate that it is necessary to work at a pressure of 400 bar and a temperature of 60 degreesC to obtain a significant yield in the extraction of the pigments. The best Carot/Chlor ratio was obtained at 200 bar and 60 degreesC. It was also found that excellent selectivity can be obtained under these operating conditions and this could enable the separation and purification of these kinds of extracted pigments. (C) 2004 Elsevier Ltd. All rights reserved.