Stable isotope characterization of olive oils. I - Compositional and carbon-13 profiles of fatty acids

Nearly 200 olive oils produced in the Mediterranean basin, mainly in Greece, during 4 yr from 1993 to 1996, were studied by gas chromatography (CC) and on-line GC-isotope ratio mass spectrometry (GC-C-IRMS). The composition of the oils in the more abundant fatty acids (C-16:0, C-16:1, C-18:0, C-18:1, C-18:2, and C-18:3) was obtained by CC after transesterification of the triglycerides into methyl esters. Using the hyphenated GC-C-IRMS technique, the C-13 contents of the three most abundant acids, C-16:0, C-18:1, and C-18:2, were measured with satisfactory accuracy. The results, analyzed in terms of geographical, temporal, and botanical factors, provide new criteria for the authentication of olive oils.