ABSTRACT
I. INTRODUCTION: SOURCES AND COMPOSITION Unrefined natural lipids, whether of animal or vegetable origin, are predominantly triacylglycerols with lower levels of diacylglycerols, monoacylglycerols, and free acids. Also present, at varying levels, are many minor components, some of which are recovered during processing and are themselves valuable by-products. Predominant among these are the phospholipids. Starting with these natural but crude materials, the phospholipid industries generate products of increasing purity for a wide range of purposes. This account is confined to the production, modification, and use of phospholipids on a commercial scale. A fuller account of this topic has been given by Michael Schneider (1,2}. and permission to draw from his material is acknowledged. Other information is available in an AOCS book (3) and in a review article (4). Phospholipids are built up from glycerol, fatty acids, phosphoric acid, and a second hydroxy compound, which frequently contains nitrogen. Among these alcohols are choline, ethanolamine, serine, inositol, and glycerol. Structures and common abbreviations for phospholipids are given in Fig. 1. The phospholipids contain four different ester groups, and there are enzymes (phospholipase A I, A2, C, and D) specific for each of them. Each of the molecules named in Fig. l represents a group of substances differing from one another in the nature of their two acyl groups. Vegetable matter usually
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F10. 1 Phosphatidic acid and its esters (phospholipids).
