Structure and Synthesis of Milk Fat. VII. Distribution of Fatty Acids in Milk Fat Triglycerides with Special Reference to Butyrate1,2

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Silicic acid column chromatography (SACC) and low-temperature-crystallization from acetone of hydrogenated milk fat were employed to isolate the low molecular-weight triglycerides from milk fat. These techniques supplemented with thin-layer chromatography (TLC) and gas chromatography (GC) of the intact triglycerides and fatty acids esterified to the glycerol molecule enabled determination of the maximum amount of butyrate present.Fractionation by SACC of goat and cow milk fat triglycerides permitted the isolation of 63 to 70 triglyceride fractions according to molecular weight. No fraction contained over 20.4 mole per cent butyrate. Fractionation by lowtemperature crystallization and GC revealed a maximum of 23.5 mole per cent of butyrate in the low molecular-weight triglyceride types. Thus, it was evident that no milk fat triglyceride fraction isolated contained more than one mole of butyrate per mole of triglyceride. This demonstrates that the normal level of butyrate present in milk fat (10 mole per cent) is distributed with medium- to long-chain fatty acids over a rather large mole per cent of the triglycerides.