**4. Conclusion**

1H-NMR fingerprinting of olive oil is a valuable analytical tool for the traceability of VOOs from different points of view, i.e. food authentication and food quality.

For authentication purposes, 1H-NMR fingerprints of VOOs analyzed by supervised pattern recognition techniques allow the determination of their geographical origin at the national, regional and/or PDO level. PLS-DA afforded the best model to distinguish the PDO *Riviera Ligure* VOOs: 88% of the Ligurian and 86% of non-Ligurian oils were correctly predicted in the external validation. At the regional level, a stable and robust PLS-DA model was obtained to authenticate VOOs from Sicily, predicting well the origin of more than 85% of the samples in the external sample set. At the national level, Greek and non-Greek VOOs were properly classified by PLS DA: >90% of the oils were correctly predicted in the crossvalidation and external validation.

Quality Assessment of Olive Oil by <sup>1</sup>

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Regarding quality control, 1H-NMR fingerprinting enables us to control the stability of VOO since this technique can detect its compositional changes due to oxidative and hydrolytic degradation. Under normal VOO storage conditions, i.e. at room temperature and protected from light, none of the signals present in the 1H-NMR spectra of VOO at time zero disappeared or experienced significant decreases or increases over a period of more than 3 and half years. Only small changes in the signals and the appearance of some low intensity signals indicate that some oxidative and hydrolytic degradation of the VOO started after one year. These results confirm the high oxidative stability of VOO at r.t., and supports the best-before date for VOO that is normally between one and one and a half years, depending on the type of container and the olive variety used. Moreover, they show that VOO during this time period does not experience any significant changes which could render its consumption hazardous. In addition, aliquots (even small aliquots of 40 mL) can be preserved at r.t. in the dark (amber glass) until analysis for at least one year, which is of great interest to control laboratories of VOO with regard to storage space and expense. Furthermore, this research is a proof-of-concept that 1H-NMR is a useful tool to study and evaluate the oxidative stability of edible oils in a quality control context at any temperature, since any toxic substances that may be generated during the degradation process can be detected and even quantified. Further studies would be needed to validate quantitative methods for this purpose.
