Phospholipids
Phospholipids are similar to triglycerides in structure in that fatty acids are attached to the glycerol molecule. The difference is that one of the fatty acids is replaced by a compound containing phosphorus, which makes the phospholipid soluble in water, while its fatty acid components are soluble in fat. The dual nature of phospholipids makes them ideal emulsifiers. The best-known phospholipid is lecithin, which is found in egg yolks. Lecithin acts as an emulsifying agent that allows hydrophobic and hydrophilic compounds to mix. Phosolipids are very important in the body as a component of cell membranes, where they assist in moving fat-soluble vitamins and hormones in and out of the cells.
Phospholipids are widely used by the food industry as emulsifiers in such products as beverages, baked goods, mayonnaise, and candy bars. Foods that naturally contain phospholipids include egg yolks, liver, soybeans, wheat germ, and peanuts.
KEY TERMS
Emulsifier
A compound that possesses both water-loving (hydrophilic) and water-fearing (hydrophobic) properties so that it disperses in either water or oil.
Hydrophobic
A term describing “water-fearing” or non-water-soluble substances.
Hydrophilic
A term describing “water-loving” or water-soluble substances.