PREPARATION OF HIGHLY PURIFIED CONCENTRATES OF EICOSAPENTAENOIC ACID AND DOCOSAHEXAENOIC ACID

Because of the complexity of marine lipids, polyunsaturated fatty acid (PUFA) derivatives in highly purified form are not easily prepared by any single fractionation technique. The products are usually prepared as the ethyl esters by esterification of the body oil of fat fish spe cies and subsequent physicochemical purification processes, including short,path distillation; urea fractionation, and preparative chromatog raphy. Lipase-catalyzed transesterification has been shown to be an ex cellent alternative to traditional esterification and short-path disti llation for concentrating the combined PUFA-content in fish oils. At r oom temperature in the presence of Pseudomonas sp. lipase and a stoich iometric amount of ethanol without any solvent, efficient transesterif ication of fish oil was obtained. At 52% conversion, a concentrate of 46% eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) was ob tained in excellent recovery as a mixture of mono-, di-, and triacylgl ycerols. The latter can be easily separated from the saturated and mon ounsaturated ethyl esters and converted into ethyl esters either by co nventional chemical means or enzymatically by immobilized Candida anta rctica lipase. Urea-fractionation of such an intermediary product can give an EPA + DHA content of approximately 85%.