Separation of long chain fatty acids with different number of unsaturated bonds by fractional extraction: experimental and COSMO-RS study.

Long chain unsaturated fatty acids (LCUFAs) are important food components and dietary supplements due to their beneficial health effects. The key process to produce high-purity LCUFAs is to separate long chain fatty acids (LCFAs) with different degrees of unsaturation and chain lengths. This process faces great challenge because of similar physico-chemical properties of fatty acids concerned. In this work, fractional extraction is proposed to separate LCFAs, using eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), conjugated linoleic acids (CLAs), oleic acid (OA) and stearic acid (SA) as model LCFAs. COSMO-RS calculations were performed for fast extractant screening and exploring the potential separation mechanism. Satisfactory distribution coefficients and high selectivities were obtained in extraction equilibrium experiments. Simulation and experimental validation of fractional extraction were performed, and high purity and high yield of CLAs were obtained. EPA and DHA could be separated thoroughly from OA, though they could not be separated each other.