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Fatty acid fraction rich in ω-3 polyunsaturated fatty acids (ω-3, PUFA), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) could be obtained by saponification of fish oil in ethanol containing alkali hydroxide followed by cooling and filtration of the resultant solution. Fatty acid compositions of fish oil and the concentrates suggest that the ratio of number of double bonds to carbon number in a fatty acid molecule is a more important factor than the degree of unsaturation or the chain length in determining the solubility of fatty acid salts in ethanol. Water content in ethanol affected significantly the efficiency of the separation with respect to yield and content of EPA and DHA in the concentrates; the lower the water content, t5e higher the efficiency. It was, however, influenced little by cooling procedure and temperature which the saponified solution experienced during the crystallization. under an optimal condition, the contents of EPA and DHA in the concentrate increased by 2.4 and 2.6 times, respectively, as compared with those in sardine oil.
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