Linolenic acid artifacts from the deodorization of oils

Gas liquid chromatography on polar open tubular columns of the methyl esters of fatty acids from vegetable oils shows that the linolenic acid in deodorized oils is accompanied by two major artifacts identified as cis‐9,cis‐12,trans‐15 and trans‐9,cis‐12,cis‐15 isomers. Physicochemical studies, isolation, and partial degradation steps showed two additional isomers with trans‐9,cis‐12,trans‐15 and cis‐9,trans‐12,cis‐15 structures. Gas liquid chromatography also showed that linoleic acid was accompanied by the trans‐9,cis‐12 isomer. These artifacts were not present in unrefined oils or bleached oils but could be induced by deodorization in the laboratory. Proportions of the two major artifacts in total 18:3ω3 are given for some vegetable oils from the retail market.