Enrichment of eicosapentaenoic acid and docosahexaenoic acid in saponified menhaden oil

Abstract

Eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) in free fatty acids (FFA) derived from saponified menhaden oil were concentrated by the solubility differences of FFA-salts in organic solvent. FFA-salts were formed by adding NaOH to a solution containing FFA. A Buchner funnel was used to separate solid phases from liquids containing FFA-salts. FFA that are rich in EPA and DHA can be recovered from the liquid phase by the addition of 12 N HCl. The effects of reaction time, the amount of NaOH, and solvent used on the concentration of EPA and DHA were systematically investigated. With a total volume of 112 mL, made up of 1.85% 15 N NaOH, 88.1% acetone, and 10.0% FFA, a reaction temperature of 30 °C, and a reaction time of 1 h, the resulting liquid phase contained 65.4 wt% EPA and DHA, with a corresponding yield of 41.5%. By replacing the acetone with a mixture of 45% acetone and 55% acetonitrile and then storing the liquid phase at -70 °C overnight, the content and yield of EPA and DHA in the final liquid phase were 61.4 wt% and 66.2%, respectively.