Abstract

Mankind has used fats and oils for thousands of years. However, their chemistry only began to be explained in the nineteenth century. They are composed mainly of triacylglycerols, which are esters of glycerol and linear long chain carboxylic acids. Chain length of the acids can vary from 4 to 12 carbon atoms. Fatty acids in oils contain one or more cis (Z) double bonds, while those in fats are more highly saturated. Melting properties of fats are complex due to packing of alkyl chains in polymorphic forms. Compositions of fats and oils depend on their origin. They may be derived from animals, fish, vegetables, seeds, or microorganisms.

Crude fats and oils may be isolated by hydraulic pressing, rendering, or solvent extraction. Removal of gums, waxes, pigments, volatile solvents, odors, and free fatty acids is accomplished by further processing that is essential for most applications. Product quality may be measured by fatty acid composition, melting point, iodine, acid and peroxide values, color and clarity, or functionality tests.

Fats, oils, fatty acids, and their derivatives are used in a variety of applications, such as foods, soaps, detergents, paints and varnishes, lubricants, and biodiesel fuels. In some applications they compete with petroleum derivatives.