Abstract

Lecithins and phospholipids occur in all living organisms. They are components of biological membranes. Commercial lecithins are by-products of the industrial production of vegetable oils. They are referred to as soya, sunflower, rape lecithin, etc, depending on their origins. The most important of these preparations is soya lecithin, so the term lecithin almost always refers to this.

Commercial lecithins are mixtures. They are made up of ca 50% phospholipids, ca 10% carbohydrates and glycolipids, and of ca 40% triglycerides, free fatty acids, sterols, and other minor components of vegetable oils. The significant components are the phospholipids, whose surface-active properties endow the lecithins with their unique position as emulsifier and dispersants. Because they are permitted in foodstuffs throughout the world without limitations, they find their broadest application in food. Native, ie, unprocessed, lecithins have also been found useful as additives to animal feed and in technical products.

Fractionation or chemical modification of lecithins yields preparations with improved activity or with a wider range of application. The surfactant and wetting properties of vegetable lecithins are improved by acetylation, hydroxylation, and partial hydrolysis. Hydrogenation improves the resistance to oxidation and aging and increases the water-binding capacity of the preparation. In spite of the multiplicity of possible applications only about 10% of the available lecithin is produced (ca 130,000 t).