Triglicerides can be formed by esterification of each of the three alcohol functions of glycerol by a fatty acid. The degrees of unsaturation of the fatty acids have a large influence on the melting point. 3 unsaturated fatty acids give an oil with a low melting point (liquid at room temperature); as the number of saturated fatty acids increases the melting point increases, so that the fully saturated triglycerides are solids at room temperature. The glycerol part is rather polar (blue on the Illustration) and the fatty acid part is rather apolar (yellow on the Illustration).
Compounds of this type that have mixed polar/apolar structure are termed ‘amphipatic’.