Lecithin is present in all living cells and is a significant constituent of nerve and brain cells.
Pure lecithin is white and waxy and darkens when exposed to air. Commercial lecithin is brown to light yellow, and its consistency varies from plastic to liquid.
Commercial lecithin, most of which comes from soya bean oil, which may be GM, contains a mixture of phosphoglycerides containing principally lecithin, cephalin and phosphatidyl inositol. Other sources are egg yolk, from where it was originally obtained, and leguminous seeds, including peanuts and maize, which also may be GM. As it can also be obtained from animal fat, vegetarians should be careful.
In cells lecithin protects the membranes and the polyunsaturated fats within the cells from oxygen attack.
As an emulsifier it lowers the surface tension of water allowing the better combining of oils, fats and water in such foods as chocolate, ice cream, margarine and mayonnaise. In bread and bakery products it increases volume and also acts as an anti-staling agent thereby extending shelf life.
In margarine it has the added advantage of preventing water leakage, so preventing spitting when frying, and protecting beta-carotene (E160a Vitamin A). In chocolate it allows a reduction in the cocoa butter content, prevents crystals forming and reduces viscosity (see E476). Soya lecithin has the same binding ability as egg yolk lecithin and can be used in place of eggs in many products. It also helps powders mix quickly and easily in milk or water.
Lecithin is also a good synergist to antioxidants in fats and oils so is often used in combination with them.For a time it was thought that lecithin supplements could help Alzheimer sufferers but this line of research did not lead anywhere.
From Wikipedia, the free encyclopedia
Lecithin is any of a group of yellow-brownish fatty substances occurring in animal and plant tissues, and in egg yolk, composed of phosphoric acid, choline, fatty acids, glycerol, glycolipids, triglycerides, and phospholipids (e.g., phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol). However, lecithin is sometimes used as a synonym for pure phosphatidylcholine, a phospholipid that is the major component of its phosphatide fraction. It may be isolated either from egg yolk (in Greek lekithos—λέκιθος) or from soy beans, from which it is extracted chemically (using hexane) or mechanically.
It has low solubility in water. In aqueous solution its phospholipids can form either liposomes, bilayer sheets, micelles, or lamellar structures, depending on hydration and temperature. This results in a type of surfactant that is usually classified as amphoteric.
Lecithin is sold as a food supplement and for medical uses.Lecithins may also be modified by a process called fractionation. During this process, lecithin is mixed with an alcohol, usually ethanol. Some phospholipids have a good solubility in ethanol (e.g., phosphatidylcholine), whereas most other phospholipids do not dissolve well in ethanol. The ethanol is separated from the lecithin sludge, after which the ethanol is removed by evaporation, to obtain a phosphatidylcholine-enriched lecithin fraction.
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