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

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Abstract
Silicic-acid column chromatography (SACC) and low-temperature crystallization from acetone of hydrogenated milk fat were used to isolate the low molecular-weight triglycerides from milk fat. These techniques supplemented with thin-layer chromatography 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 63-70 trigly-ceride fractions according to molecular weight. No fraction contained over 20.4 mole % butyrate. Fractionation by low-temperature crystallization and GC revealed a maximum of 23.5 mole % of butyrate in the low-molecular-weight trigylcerides. No milk fat trigylceride fraction contained more than 1 mole of butyrate/mole of trigylceride. This demonstrates that the normal level of butyrate present in milk fat (10 mole %) is distributed with medium- to long-chain fatty-acids over a rather large mole % of the triglycerides.