Different fatty acids composition of fat globule core and membrane in ewe's milk

Most studies investigating the fatty acid composition of milk are carried out on its total fat content. Aim of this work was to demonstrate the difference in fatty acid composition of the core and the fat membrane of fat globule. After separating triglycerides from phospholipids of milk fat globule, both samples were analyzed by GLC as methyl esters. This differential extraction showed that in ewe's milk the composition of fatty acid derived from the hydrolysis of triglycerides was different from that of fatty acids derived from phospholipids. The long-chain polyunsaturated fatty acids were present to a greater degree within the phospholipids, compared to the triglycerides: the C20:4 is absent in the core, while no short-chain C4:0 and C8:0 were detected in the membrane of fat globules. The C14:0, C16:0, C18:0 and C18:1 fatty acids are present in greater amount in the cream, while the eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), conjugated linoleic acid (CLA) and the fatty acids precursors of the latter are better represented within the globule membrane. The unsaturated/saturated fatty acids ratio was 0.56 in the fat globule core and 0.86 in the fat globule membrane.