The present invention relates to fatty acid fractionation for polyunsaturated fatty acid fraction enrichment, and the present invention also relates to employing enzymatic hydrolysis and enzymatic esterification in the course of obtaining the fractions.
Fatty acids of the n-6 and n-3 series have a nutritional value, in particular as precursors in the biosynthesis of prostaglandins. It may be advantageous to have available fractions enriched in these fatty acids for various nutritional and cosmetic applications. These fatty acids are found in nature principally in the form of triglycerides. Free fatty acids are obtained industrially from triglycerides by hydrolysis at a high temperature and under a high pressure. In order then to fractionate these fatty acids, several methods have been developed, for example crystallization, distillation, the formation of inclusion complexes or chromatographic techniques. Application of these methods may bring about degradation in the case of polyunsaturated fatty acids or prove to be too costly to be applied industrially.
Enzymatic methods represent an alternative to the preceding methods since they enable reactions to be carried out under mild conditions using little energy and equipment which is less stressed.
Enzymatic processes are known, for example from Matthew J. Hills et al in JAOCS, Vol.67, no.9, p.561-563, for fractionating fish oil and evening primrose oil fatty acids based on the fact that the kinetics of the esterification by butanol catalysed by rape lipases and Mucor miehei would be a function of the degree of saturation of the acid to be esterified. After esterification of fatty acids with a higher degree of saturation, the esters are separated from the fatty acids which have not reacted, by thin layer chromatography.