Some Commercial Atlantic Herring Oils; Fatty Acid Composition

Abstract

Twelve commercial samples of oil from Atlantic herring (Clupea harengus L.) were examined for fatty acid composition by gas–liquid chromatography. Individual fatty acid components varied widely between these oils, but an assessment of the respective totals of saturated, monounsaturated, and polyunsaturated acids from these oils and from oils of other species has led to an empirical formula giving the total per cent polyunsaturated fatty acids in marine oils as: total polyunsaturated fatty acids = 10.7 + 0.337 (iodine value oil — 100)In the Atlantic herring oils studied the average proportions of the saturated, monounsaturated, and polyunsaturated fatty acids were 20, 60, and 20%, respectively. In comparison with herring oil analyses reported from other areas the total saturated acids in the Atlantic herring oils are slightly lower, but there is general agreement that hexadecanoic acid averages about 60% of the total saturated fatty acids. Relationships which are fairly consistent among other acids and apparently not related to iodine value include the ratio of hexadecanoic acid to hexadecenoic acid plus octadecenoic acid, the ratio of C20 and C22 successor acids to C18 linoleic-type precursor acids, and the ratio of linolenic-type acids compared to immediate precursors of the same chain length. As iodine value increases the saturated acids increase slightly, and in the linolenic type acids the ratio of C20 to C18 fatty acids increases more noticeably than the ratio of C22 to C18. The ratio of C22 to C20 linolenic-type acids accordingly decreases with increasing iodine value. The ratio of total linolenic-type acids to total linoleic-type acids apparently increases with increasing iodine value. Comparisons are made with oil analyses of clupeids taken in other oceanic areas.