Quantitative Fatty Acid Analysis of Milk Fat by Gas-Liquid Chromatography

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Abstract
A procedure was developed for quantitative analysis of the fatty acids of milk fat. Methyl esters of the acids were prepared by methanolysis, extracted with ethyl chloride, and separated by gas-liquid chromatography (GLC) with diethylene glycol succinate as liquid phase. Known mixtures of methyl esters were used in determining factors for correction of peak areas for losses from evaporation of short carbon chain esters and/or variations in relative detector response among the esters under the conditions of the actual analysis. Replicate samples of milk fat esters were analyzed and compared with data obtained by spectrophotometry and with results of others determined by ester distillation and GLC techniques. All the major and most of the known minor fatty acids of milk fat were determined. The accuracy of the method is superior to previous ester fractionation techniques and it yields additional data on the minor -component fatty acids. Although the method is useful for comparing the polyunsaturated fatty acid compositions of different milk fats, conventional spectrophotometric analyses give more detailed information on conjugated and nonconjugated components. The method described provides a more simple and precise way of analyzing the fatty acid composition of milk fat than is currently possible by any other means.