**4. Conclusions**

NMR spectroscopy, combined with multivariate analysis techniques, successfully allowed characterization of metabolomic profiles of EVOOs, and their linkage with main cultivar composition and/or country of origin. Moreover, the fine composition of olive oil, and therefore its sensory characteristics, besides being strongly dependent on the nature of the cultivar used for its production, is also influenced by several other factors, like climate (temperature, relative humidity of summer months, yearly rainfall) as well as agricultural practices and technological factors (crop year, oil extraction system and storage time). In this work, the 1H NMR-based MVA approach was used on EVOOs collected over a four-year period (2009–2012), considering the potential influence of the historical meteorological parameter averages. Marked differences existing between Italian and foreign EVOO samples were observed, in particular when the three studied Italian regions (Tuscany, Sicily and Apulia), were considered separately. Higher differences in average rainfall and temperature generally resulted associated with a more constant discriminating ability of the studied OPLS-DA models. However, conclusive correlations could not be obtained by using the simple climate descriptors here considered, and further studies are required in order to obtain sound correlation of detailed climate parameters with specific EVOO metabolic profiles. It should be noted that the simplified approach used which takes into account indicative average weather data (rather than specific climate data variation across each country), was chosen for the ease of average climate data availability for each country. Nevertheless, these results sugges<sup>t</sup> the possible use of NMR-based metabolic profiling for olive oils geographical origin prediction and assessment of the possible correlation with climate data. In fact, among the EVOOs studied here, the Tunisian case appears to be an interesting key issue, due to the recent introduction of Tunisian olive oil into the EU market. In this respect, it should be pointed out that the present oil characterization study is only aimed at clearly indicating possible metabolic profile differences among oils, rather than quality ranking.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2304-8158/6/11/96/s1, Table S1: Fatty acid composition data calculated on the basis of 1H NMR, expressed in molar percentage. Table S2: One-Way ANOVA.

**Acknowledgments:** This work was supported by the project "Strumenti di supporto per la valutazione del rischio di frodi nel sistema agroalimentare—Sviluppo di metodiche analitiche per l'accertamento dell'origine geografica degli oli di oliva" financed by the MIPAAF (Ministero delle Politiche Agricole Alimentari e Forestali), DM 16/12/2015.

**Author Contributions:** D.R., Na.S., L.D.C. and F.P.F. conceived and designed the experiments; P.D.R. and Ni.S. prepared the samples for NMR analysis; performed the NMR experiments; D.M. and L.D.C. analyzed and interpreted the NMR and statistical data; E.P. contributed samples and analysis tools; D.R., Na.S., L.D.C. wrote the paper; D.R. and F.P.F. supervised statistical analyses, wrote and reviewed drafts of the paper and contributed to the final writing. All authors read and approved the final manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest.
