Concentration of docosahexsaenoic acid from tuna oil by a combination of solvent crystallization and lipase‐catalyzed ethanolysis.

The docosahexaenoic acid (DHA) was concentrated from tuna oil fatty acid using solvent crystallization combined with lipase‐catalyzed ethanolysis. In the first step, solvent crystallization was carried out to concentrate DHA from tuna oil fatty acid using acetonitrile as a solvent. The optimal conditions of solvent crystallization were the crystallization temperature of −40°C and the fatty acid to solvent ratio of 1:8 (w/v). This step increased the DHA content in the original tuna oil fatty acid from 22% up to 61%. In the second step, lipase‐catalyzed ethanolysis was conducted with DHA‐enriched fatty acid from the first step using Lipozyme RM IM (from Rhizomucor miehei) as a biocatalyst. The optimum conditions of this second step were the reaction temperature of 20°C and the molar ratio of 1:1 (fatty acid to ethanol). Overall, DHA enrichment with purity of 85% was obtained by the two step processes. [ABSTRACT FROM AUTHOR]