A total of 113 samples of various types of palm and palm kernel oil products, their fractions, palm-based and non-palm-based cooking oils obtained from local manufacturers and the retail market were analysed for their trans-fatty acid compositions and contents by capillary gas chromatography. Trans-fatty acids were generally absent in crude palm and palm kernel oils. However, they were present at 0.01%-0.06% in refined palm kernel products and 0%-0.61% in refined palm products, all well below the 1.0% level stipulated by some importers. These trans-fatty acids were formed from their natural cis -isomers as a result of the high temperature used during deodorization.
In cooking oil, the trans-fatty acid contents of palm-based products were 0.25%-0.67%, again well below 1%. However, in the non-palm-based cooking oils, the contents of the 14 samples ranged from 0.43%-3.83%. The higher contents in the non-palm-based oils were expected as they had high contents of unsaturated fatty acids, which are more prone to isomerization at elevated temperatures