Chromatographic fingerprints: pros and cons in olive oil authentication

Virgin olive oil (VOO) stands out for its exceptional sensory attributes and nutritional content. Sensory quality, assessed by trained panels following a standardized method, is one of the parameters defining the commercial category of VOO. Implementing instrumental methods would offer a preliminary screening for sample assessments by sensory panels. Moreover, producers often distinguish their VOO by specifying the cultivar and geographical origin, implying the need of verifying label-declared information. This verification currently relies on documentary review, lacking an officially accepted procedure.
Fingerprinting, identifying patterns in highly dimensional data, is a cutting-edge strategy in food analysis. A fingerprinting approach applied to selected metabolite fractions related to the characteristic to authenticate, allowed developing Partial Least Square-Discriminant Analysis (PLS-DA) classification models that distinguished VOOs according to their commercial class, cultivar or geographical origin.
The volatile fraction fingerprint, obtained by HS-SPME–GC–MS from >300 VOOs, allowed the classification of nearly 80% of the samples. This resulted in 23% of uncertain samples being assessed by the panel, significantly reducing the panels' workload.
On the other hand, sesquiterpene hydrocarbons (SHs) in VOO are largely shaped by olive cultivar and growing area, with minimal impact from post-harvest processing and storage, making them ideal for authentication models. In varietal authentication, the approach successfully discriminated VOOs from the Arbequina cultivar from different areas, while for geographical authentication, it proved effective at different levels, including the EU, country, and even the PDO provenance. PLS-DA, depending on the variable chosen for supervising the model, identifies features characteristic of either the variety (beyond geographical origin) or the pedoclimatic condition (beyond the cultivar).
Despite these achievements, some challenges in chromatographic fingerprinting need addressing before it can serve as a universal authentication strategy. This presentation will explore current challenges and prospects of applying fingerprinting coupled to chemometric modeling to authenticate other food commodities.