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-stepprocess: fatty acid extraction by direct saponification of biomass,polyunsaturated fatty acid (PUFA) concentration by urea inclusion complexingand EPA isolation by high-performance liquid chromatography (HPLC). Twosolvents were tested for direct saponification of lipids in biomass. Themost efficient solvent, ethanol (96% v/v), extracted 75% ofthe fatty acids. PUFAs concentration by urea inclusion employed a urea/fattyacid ratio of 4:1 wt/wt at the crystallization temperatures of 4°C and28°C. Concentration factors were similar at both temperatures, but theEPA and AA recoveries were higher at 28°C (67.7% and 61.8%for the two acids, respectively). EPA and AA were purified from this PUFAconcentrate using analytical scale HPLC and the best results of thisseparation were scaled up to preparative level (4.7 i. d. × 30 cmcompression radial cartridge). A 94.3% pure EPA fraction and a81.4% pure AA fraction were obtained. Suitability of severalmicroalgae (Porphyridium cruentum, Phaeodactylum tricornutum and Isochrysisgalbana) and cod liver oil as sources of highly pure PUFAs, mainly EPA, wascompared.