Fatty Acids & Glycerine
For the technically minded
No natural oil or fat is based on a single fatty acid. Each contains a mixture of fatty acids in proportions that are dependent on the source of the oil. Sometimes one particular fatty acid predominates, as does lauric acid in coconut oil. There are also instances where a particular fatty acid may have only one commercially suitable source: ricinoleic acid from castor oil, for example.
With the exception of tall oil – a mixture of rosin acids, terpenes and fatty acids – nature seldom provides fatty acids in the free, unreacted state. In most oils they occur in the form of triglycerides. These are esters in which one molecule of glycerol is chemically combined with three molecules of fatty acid. Structurally, natural fatty acids have all straight chains of carbon atoms with a terminal carboxyl group.
Predominantly these acids have an even number of carbon atoms and an essential difference between any two adjacent members of the series is the length of the carbon atom chain. The most abundant fatty acids are those with 16 and 18 carbon atoms. The length of the chain has a profound bearing on the properties of the acid. The meeting point, for example, increases with chain length.
At one end of the chain the terminal carbon atom has three hydrogen atoms attached to it. At the other end, the terminal carbon atom forms part of the carboxyl (COOH) group which gives the weak acidic properties of these chemical compounds. Most or all of the intermediate carbon atoms each have two hydrogen atoms attached. In this case the acid is described as "saturated". If only one hydrogen atom is attached to each of two adjacent chain members then the fatty acid is described as "unsaturated". If two or more pairs of carbon atoms have only one hydrogen attached the fatty acid is described as polyunsaturated.