Determination of geographical origin of commercial tomato through analysis of stable isotopes, elemental composition and chemical markers

In recent years, the geographical authentication of different agro-products, including vegetables, has gained an increasing amount of attention. This study investigated different approaches, both independently and in combination, to assign the country of origin to commercial tomato samples from Slovenia, Italy, Spain and Morocco. To create a model for their traceability, three sets of parameters were used: stable isotopes of the major bioelements (δ13C, δ15N, δ18O, δ34S), macro and micro elements (P, K, Ca, S, Cl, Zn, Br, Rb, Sr), and chemical markers (total antioxidant potential, total phenolic compounds, ascorbic acid, lutein, nitrates and nitrites, ammonium). The data obtained were analysed using the supervised pattern-recognition technique of multivariate discriminant analysis. The statistical analysis based on leave-one-out cross-validation revealed that the best overall success rate was achieved when using either the combination of all three sets of parameters, or only the elemental content data. In both cases, correct classification was obtained for 80% of the samples. Moreover, the present study highlights the first characterisation and classification of commercial tomato samples using the combination of the methodologies proposed.