Fatty Acid Composition of the Phospholipids and Other Lipids in Milk

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Abstract
Milk lipids separated by silicic acid chromatography were identified by infrared spectrometry and paper chromatography. The major phospholipids were phosphatidyl cholines (PC), phosphatidyl ethanolamines (PE) and sphingomyelins, but cerebrosides, phosphatidyl serines (PS) and phosphatidyl inositols were also present. The various lipids showed marked differences in fatty-acid composition as determined by gas-liquid chromatography. Mole percentages of saturated fatty acids were higher in cerebrosides and sphingomyelins than in triglycerides, PC, PS and PE. Triglycerides contained less higher-molecular-weight even and odd C20-C24 acids. No appreciable amounts of acids below C10 were found in the phospho-lipids, but traces were present in the cerebrosides. The principal saturated acid was stearic in PE and PS and palmitic in the other lipids. Since the unsaturated fatty acids of PE, PS and PC amounted to over 50% of the total acids, they must occur at both the [alpha]- and [beta]-positions of the glycerol moiety of these phospholipids.