ABSTRACT
Lipids are widely distributed, and almost every natural food contains some quantity of them. Lipids are often added to foods during their preparation as a tenderizing agent, as one phase of an emulsion, as a method of transferring heat as in frying, or for flavor and richness in foods. Fats and oils (triglycerides; triacylglycerols) are characterized by their insolubility in water and solubility in organic solvents. One physical constant often used to identify fats and oils is specific gravity. The index of refraction of an oil is often used to indicate the degree of hydrogenation. Increases in the chain length or unsaturation of a fatty acid cause an increase in refractive index. Prevention of rancidity is a concern in the storage life of a fat or foods containing fats.
