Preparation and analysis of lipid extracts from milk and other tissues

Abstract

Simple and quick analytical methods for the determination of the phosphorus, nitrogen, long chain base-nitrogen, and carbohydrate contents of samples containing even very low quantities of polar lipids have been devised, in order completely to follow fractionation schemes of lipids from milk or other fat-rich tissues. With these analytical methods strong evidence was obtained indicating that a large proportion of the polar lipids present in milk consists of proteolipids, and mucolipids or other glycolipids. Aqueous washing of chloroform-methanol lipid extracts had destroying effects on these complex molecules, which are also partially broken down by lyophilization, as well as by acidic treatment, including silicic acid chromatography when the finest particles of the adsorbent are not completely removed. Possible explanations for these effects are given and bibliographic data presented supporting the statements. The commonly accepted procedures for manipulating lipid extracts are revised.