Downstream processing and purification of eicosapentaenoic (20:5n-3) and arachidonic acids (20:4n-6) from the microalga Porphyridium cruentum

Eicosapentaenoic acid (FPA, 20:5n-3) and arachidonic acid (AA, 20:4n-3) were obtained from the microalga Porphyridium cruentum by a three-step process: fatty acid extraction by direct saponification of biomass, polyunsaturated fatty acid (PUFA) concentration by urea inclusion complexing and EPA isolation by high-performance liquid chromatography (HPLC). Two solvents were tested for direct saponification of lipids in biomass. The most efficient solvent, ethanol (96% v/v), extracted 75% of the fatty acids. PUFAs concentration by urea inclusion employed a urea/fatty acid ratio of 4:1 wt/wt at the crystallization temperatures of 4 degrees C and 28 degrees C. Concentration factors were similar at both temperatures, but the EPA and AA recoveries were higher at 28 degrees C (67.7% and 61.8% for the two acids, respectively). EPA and AA were purified from this PUFA concentrate using analytical scale HPLC and the best results of this separation were scaled up to preparative level (4.7 i. d. x 30 cm compression radial cartridge). A 94.3% pure EPA fraction and a 81.4% pure AA fraction were obtained. Suitability of several microalgae (Porphyridium cruentum, Phaeodactylum tricornutum and Isochrysis galbana) and cod liver oil as sources of highly pure PUFAs, mainly EPA, was compared.