A process for high yield and scaleable recovery of high purity eicosapentaenoic acid esters from microalgae and fish oil

A low expense process has been developed for recovering esterified eicosape ntaenoic acid (EPA) from microalgae and fish oil. Over 70% of the EPA conte nt in the esterified crude extract of microalgae were recovered at purities exceeding 90%. The recovery scheme utilizes either wet or freeze-dried alg al biomass. The process consists of three main steps: (1) simultaneous extr action and transesterification of the algal biomass; (2) argentated silica gel column chromatography of the crude extract; and (3) removal of pigments by a second column chromatographic step. Argentated silica gel chromatogra phy recovered about 70% of the EPA ester present in the crude fatty eater m ixture of fish oil, but at a reduced purity ( similar to 83% pure) compared to the microalgal-derived EPA. The optimal loading of the fatty ester mixt ure onto the chromatographic support was about 3% (w/w) but loadings up to 4% did not affect the resolution significantly. The process was scaled up b y a factor of nearly 320 by increasing the diameter of the chromatography c olumns. The elution velocity remained constant. Compared to the green alga Monodus subterraneus, the diatom Phaeodactylum tricornutum had important ad vantages as a potential commercial producer of EPA. For a microalgal EPA pr ocess to be competitive with fish oil derived EPA, P. tricornutum biomass ( 2.5% w/w EPA) needs to be obtained at less than $5 kg(-1) If the EPA conten t in the alga is increased to 3.5%, the biomass may command a somewhat high er price. The quality of microalgal EPA compares favorably with that of the fish oil product. Compared to free fatty acid, EPA ester is mon stable in storage. Shelf-life is extended by storing in hexane. The silver contaminat ion in the final purified EPA was negligibly small ( < 210 ppb). (C) 2000 E lsevier Science Ltd. Ail rights reserved.