The lipids of fish. 8. The triglycerides and cholesterol esters of haddock flesh

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Abstract
An extract of haddock flesh was prepared which contained essentially all of the triglycerides and cholesterol esters, but none of the acidic lipids of phospholipids. Other components were free cholesterol, waxes, aliphatic alcohols and hydrocarbons. This mixture was separated chromatographically on silica gel, the primary fractions being rechromatographed. Hydrocarbons, cholesterol esters and triglycerides, which were fairly well separated from each other, all showed subfractionation according to unsaturation. Esterified higher aliphatic alcohols were separated from free alcohols. The fatty acids of the cholesterol esters were of an unusually high average unsaturation, owing mainly to a high content of C20 and C22 unsaturated acids and, to a less extent, to a rather low content of saturated acids. The fatty acids of the triglycerides showed considerable resemblance to those of haddock-depot fat and, alone among the flesh lipids, contained a major proportion of hexadecanoic acid. A triglyceride fraction, less strongly adsorbed on silica gel than the bulk of the triglycerides, contained unsaturated fatty acids much enriched in C16 and C18 derivatives at the expense of more highly unsaturated C20 and C22 acids, and hence its mean unsaturation was much lower. Each class of lipid appears to have a characteristic fatty acid composition.