The colour stability of some commercial palm fatty acids at 90°C, 110 ° C and 130ºC was investigated. The degree of whiteness of palm fatty acid started to decrease at 110ºC and rate in percentage of whiteness decreasing was faster at higher temperatures. The general order of colour stability of palm fatty acids to heat at 130ºC and 110ºC are respectively as below:

98% palmitic acid > double pressed > triple
pressed > single pressed > 70% strearic > 70% oleic acid.
98% palmitic acid > 70% stearic acid > triple pressed > double pressed > single pressed > 70% oleic acid.

The likely factors, viz. minor constituents and trace unsaturated acids, affecting the colour development were studied. Minor constituents were isolated from the various types of palm fatty acids and were found to consist mainly of straight chain hydrocarbons. The major hydrocarbons present in 70% oleic acid were tentatively identified as hydrocarbons C₂₆H₅₀ and C₂₆H₅₂. The exact structures are yet to be identified. The minor components which affect the colour stability of palm fatty acid could be removed by silicic acid or citric acid treatments. Dimers of oleic acid-oleic acid and oleic acid linoleic acid were among the components identified in the yellow components fraction isolated from heated palm fatty acids which could be causing the yellow colour. The results indicated that the problem of colour stability of the palm fatty acids is rather complex and is mostly likely due to the presence of traces of unsaturated fatty acids and some unknown minor components in fatty acids.