RAPID ASSESSMENT OF THE ADULTERATION OF VIRGIN OLIVE OILS BY OTHER SEED OILS USING PYROLYSIS MASS-SPECTROMETRY AND ARTIFICIAL NEURAL NETWORKS

Curie-point pyrolysis mass spectra were obtained from a variety of extra-virgin olive oils, prepared from various cultivars using several mechanical treatments. Some of the oils were adulterated (according to a double-blind protocol) with different amounts of seed oils (50-500 ml of soya, sunflower. peanut, corn or rectified olive oils per litre of mixed oil). Canonical variates analysis indicated that the major source of variation between the pyrolysis mass spectra was due to differences between the cultivars, rather than whether the oils had been adulterated. However, artificial neural networks could be trained (using the back-propagation algorithm) successfully to distinguish virgin oils from those which had been adulterated.