Student Korea University Seoul, Seoul-t'ukpyolsi, Republic of Korea
Abstract: Docosahexaenoic acid (DHA) is one of important polyunsaturated fatty acids with diverse biological activities namely, reducing cholesterol, prevention of atherosclerosis, supporting brain development, etc. In this study, highly concentrated DHA was produced from tuna oil fatty acid using a combination of solvent crystallization and enzyme reaction. In the first step, solvent crystallization was carried out to concentrate DHA from tuna oil fatty acid. Among the five solvents tested, acetonitrile was the suitable solvent to concentrate DHA for crystallization process. The optimal conditions of the first step were the crystallization temperature of -40oC and the fatty acid to solvent ratio of 1:8 with acetonitrile as a solvent. Under the optimal conditions, DHA was concentrated up to 61% in the liquid fraction from an initial value of 22% in the tuna oil fatty acid. In the second step, lipase-catalyzed ethanolysis was conducted to further concentrate DHA with DHA enrichment obtained from the first step using Lipozyme RM IM (from Rhizomucor miehei) as a biocatalyst. The optimal conditions of the second step were the reaction temperature of 20oC and the substrate molar ratio of 1:1 (fatty acid to ethanol). Finally, highly concentrated DHA (purity > 85%) was produced using a combination method of two step processes.