ABSTRACT
Fatty acids are aliphatic, usually straight chain, monocarboxylic acids. The broadest definition includes all chain lengths, but most natural fatty acids have even chain lengths between C4 and C22, with C18 the most common. Natural fatty acid structures reflect their common biosynthesis — the chain is built in two-carbon units and cis double bonds are inserted at specific positions relative to the carboxyl carbon. Over 1000 fatty acids are known with different chain lengths, positions, configurations and types of unsaturation, and a range of additional substituents along the aliphatic chain. However, only around 20 fatty acids occur widely in nature; of these, palmitic, oleic, and linoleic acids make up ~80% of commodity oils and fats. Figure 1.1 shows the basic structure of fatty acids and a number of the functional groups found in fatty acids. A list of many of the known structures, sources, and trivial names is available online (Adlof and Gunstone, 2003).
