Lipid Components of the Fat-Globule Membrane

Abstract

Lipid components were extracted from fat-globule membranes prepared by two procedures. One method (Scheme I) started with cold, pooled milk, whereas in the other procedure (Scheme II) freshly drawn, uncooled milk served as the source. The lipids obtained were resolved by gradient elution from a silicic acid chromatographic column. The following lipid classes were identified as components of the fat-globule membrane: carotenoids, a squalene-like compound, cholesterol esters, cholesterol, a unique triglyceride mixture similar to the high-melting glyceride fraction, mono-diglycerides, phospholipids and, from some preparations, unesterified fatty acids. The minor differences in composition between the membrane lipids reflected the age of the milk and the method of preparation. Membranes isolated from the pooled milk by Scheme I contained lower concentrations of phospholipids and associated proteins. Carotenoids, cholesterol esters, and the squalene-like component were removed from the membranes by washing with ethyl ether. © 1961, American Dairy Science Association. All rights reserved.