Edmund Mach Foundation finds all the imported Tunisian olive oils were found to be of poor quality. IRMS and H-NMR are powerful techniques for verifying claims of origin.
Isotope Ratio Mass Spectrometry (IRMS), 1H Nuclear Magnetic Resonance (1H-NMR), conventional chemical analysis and chemometric elaboration were used to assess quality and to define and confirm the geographical origin of 177 Italian PDO (Protected Denomination of Origin) olive oils and 86 samples imported from Tunisia.
Italian olive oils were richer in squalene and unsaturated fatty acids, whereas Tunisian oils showed higher δ18O, δ2H, linoleic acid, β -sitosterol, sn-1 and 3 diglyceride values.
Furthermore, all the Tunisian samples imported were of poor quality, with a K232 and /or acidity values above the limits established for extra virgin olive oils.
By combining isotopic composition with 1H-NMR data using a multivariate statistical approach, a statistical model able to discriminate olive oil from Italy and oil imported from Tunisia was obtained, with an optimal differentiation ability arriving at around 98%.Comparing Italian and Tunisian olive oils,