Distribution of Isomeric Octadecenoic Fatty Acids in Commercially Hydrogenated Olive Oil

Abstract

AbstractSamples of cooking fats and margarines prepared from hardened olive oil were analyzed for positional isomers of the cis and trans monoene fraction. The fats were transesterified and the methyl esters were separated by silver nitrate thin layer chromatography. The monoene fraction was recovered from the plates and the positional isomers were determined by epoxidation, cleavage of methyl epoxy‐octadecanoates and gas chromatographic analysis of the aldehyde esters. Hydrogenated olive oil products contain 70–75% monoenes. 25–27% of the fatty acids are in the form of trans 18:1 isomers. The position of the double bond appears to be distributed from Δ7 to Δ13. This distribution over the carbon chain is 2–4 times higher in the trans fraction of the monoenes.