ABSTRACT
Lipids form one of the major bulk constituents in food and other biological systems. This group of organic biomolecules can be classified into three groups: simple lipids (triglycerides, steryl esters, and wax esters), compound lipids (phospholipids, glycolipids, sphingolipids, and lipoproteins), and derived lipids (fatty acids, fatsoluble vitamins and provitamins, sterols, terpenoids, and ethers). Lipids occur in animals and plants either as storage lipids, which are potential sources of energy by beta oxidation, or as membrane lipids. Storage lipids are triglycerides, whereas membrane lipids include phospholipids, sterols, sphingolipids, and glycolipids. Many foods of plant origin contain highly unsaturated lipids. Lipids of animal origin have lower levels of unsaturated lipids, but they contain certain amounts of the higher unsaturated fatty acids.
