NMR Studies on Italian PDO Olive Oils and their Potential in Olive-Tree-Derived Products Characterization

In Italy, 42 PDO extra virgin olive oil (EVOOs) are present to date, with the chronologically first one registered in late 1996. PDO EVOOs are broadly distributed along Italy with a higher concentration in the central and southern regions due to the optimal pedoclimatic conditions for olive growth (Olea europaea L.). In this review, NMR (nuclear magnetic resonance) studies focused on Italian PDO EVOOs and the application of NMR spectroscopy in the analysis of other olive-tree-derived products are reported. NMR is historically known as the principal analytical technique useful for structural characterization of single molecule in solution. In the past few years, NMR evolved to cover a pivotal role for the analysis of different chemical compounds present in a mixture, without the need of any chemical derivatization of sample. Concerning the H-1 NMR spectrum of a typical EVOO sample, the dominant signals due to acylglycerols, together with other minor components like aldehydes, sterols, and terpens, can be characterized within a single experiment in the organic extract of olive oil. The minor component content is particularly interesting because it allows for geographical origin discrimination and cultivar discrimination. Other products derived from the olive tree and investigated by NMR have also been discussed, specifically, table olives, pomace, and olive paste. Practical Applications: The studies here highlight the capability of NMR in discriminating Italian PDO EVOOs from EVOOs of other countries, Italian PDO EVOOs of different restricted area within the same Italian region, and EVOOs obtained from different cultivars. In addition, NMR spectroscopy allows the evaluation of chemical constituents in olive-tree-derived products like olive paste, pomace, and wastewater, detecting bioactive compounds. Therefore the NMR approach could be practically applied in the study of EVOO and olive-tree-derived products by control agencies, regulatory authorities, for the disclosure of new fraud practices and to protect PDO products. Practical applications could also involve the search of olive-tree-based bioactive compounds for their potential use as nutraceuticals.