Basic concept of fatty acid
Compounds of carbon, hydrogen and oxygen with a functional group, a 
carbonyl carbon, CH3.(CH2)n.COOH. The fatty acids, the simplest of the 
lipids, are defined as monocarboxylic acids that tend to be more soluble
 in organic solvents than in water.
Most fatty acids in food consist of a straight of carbon atoms ending 
with a carboxyl group, that is soluble in water and non polar 
hydrocarbon chain that is insoluble in water but soluble in the common 
organic solvents. They may be double bond between some of these carbon 
atoms.
The melting point of a fatty acid is affected by its chain length, its 
degree of unsaturation and whether the double bonds are cis or trans.
The number of known natural fatty acids exceeds 1000 although only a relatively small number – perhaps 2o—50 are of common concern. A large number of fatty acids exist in nature because the hydrocarbon chain may be of varying lengths (i.e. containing a varying number of carbon atoms linked together) an may have different degrees of unsaturation (unsaturation refers to the presence of double bonds between carbon atoms within the hydrocarbon chain).

 
 
