Geographical Origin Assessment of Extra Virgin Olive Oil via NMR and MS Combined with Chemometrics as Analytical Approaches

Abstract

Geographical origin assessment of extra virgin olive oil (EVOO) is recognised worldwide as raising consumers' awareness of product authenticity and the need to protect top-quality products. The need for geographical origin assessment is also related to mandatory legislation and/or the obligations of true labelling in some countries. Nevertheless, official methods for such specific authentication of EVOOs are still missing. Among the analytical techniques useful for certification of geographical origin, nuclear magnetic resonance (NMR) and mass spectroscopy (MS), combined with chemometrics, have been widely used. This review considers published works describing the use of these analytical methods, supported by statistical protocols such as multivariate analysis (MVA), for EVOO origin assessment. The research has shown that some specific countries, generally corresponding to the main worldwide producers, are more interested than others in origin assessment and certification. Some specific producers such as Italian EVOO producers may have been focused on this area because of consumers' interest and/or intrinsic economical value, as testified also by the national concern on the topic. Both NMR- and MS-based approaches represent a mature field where a general validation method for EVOOs geographic origin assessment could be established as a reference recognised procedure.

Keywords: chemometrics; elemental profiling; extra virgin olive oil; geographical origin; isotope ratio; mass spectrometry; metabolomics; molecular fingerprinting; nuclear magnetic resonance (NMR) spectroscopy.

Figure 1

Comprehensive mechanism-based scheme summarizing the application of NMR and MS techniques associated with chemometric tools in the specific subject of EVOOs’ geographical origin analysis.

Figure 2

Graphical representation of the partition of selected nuclear magnetic resonance (NMR)-based studies on extra virgin olive oils (EVOOs)’ geographical origin assessment.

Figure 3

Graphical representation of the partition of selected mass spectrometry (MS)-based studies on extra virgin olive oils (EVOOs)’ geographical origin assessment.

Figure 4

Chemometric analyses associated with NMR and MS techniques in selected published papers reported according to the frequency of their specific use (a) and their first appearance in the literature reviewed here (b).

Figure 5

Temporal distribution from 1997 to 2021 (to date) of selected NMR- and MS-based studies for geographical origin assessment of EVOOs. Data from systematic research on https://www.scopus.com/ and https://scholar.google.com/ (accessed on 1 December 2021).

Figure 6

Evolution over five-year period of main ¹H NMR frequencies (400, 500, and 600 MHz) reported in here selected studies.

Figure 7

Evolution over five-year period of molecular-fingerprint and chromatography MS techniques reported in here selected studies.

Figure 8

Countries of origins for EVOOs subject to geographical origin assessment in selected NMR and MS-based studies. Data from systematic research on https://www.scopus.com/ and https://scholar.google.com/ (accessed on 1 December 2021).