Fatty acids of long chain length in baltic herring lipids

Abstract

AbstractThe component fatty acids with carbon numbers exceeding 22 in flesh lipids of Baltic herring caught in May and September 1967 in the Turku archipelago have been studied. The total lipid content of the flesh of the herring was 3.5% on average in May and 7.2% on average in September. The fatty acids in the lipids were converted to methyl esters which were resolved and analyzed by urea adduct fractionation, thin layer chromatography and programmed temperature gas liquid chromatography (GLC). The lipids of the herring caught in May were found to contain 15 fatty acids with 24–32 carbon atoms, whereas the lipids of the herring caught in September were found to contain only nine fatty acids with 24–28 carbon atoms. The differences are probably due to nutritional factors. The long chain fatty acids in the lipids of the herring caught in September were isolated by preparative GLC and their structures were studied by UV spectroscopy before and after alkali isomerization, by IR spectroscopy and by GLC of their ozonization products. The identified acids were tetracosanoic, 15‐tetracosenoic, 12,15,18,21‐tetracosatetraenoic, 9,12,15,18,21‐tetracosapentaenoic, 6,9,12,15,18,21‐tetracosahexaenoic, 17‐hexacosenoic, 11,14,17,20,23‐hexacosapentaenoic, 8,11,14,17,20,23‐hexacosahexaenoic and 4,7,10,13,16,19,22‐octacosaheptaenoic acids. The proportion of the fatty acids containing over 22 carbon atoms in the lipids of fall herring is much higher than has been found earlier in the lipids of marine teleost fish; the reason may be due at least partly to differences in analytical methods.