Scientific Study

BACKGROUND: In the present study, a metabolomic-based approach was used to discriminate different hazelnut cultivars as well as to trace their geographical origin. On this basis, ultra-high-pressure liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (UHPLC-ESI/QTOF-MS), able to profile phenolic and sterolic compounds, was set up. RESULTS: Compounds identification was achieved thanks to accurate monoisotopic mass and isotopic pattern, against an in-house database. The screening approach was designed to discern 15 hazelnut cultivars and to discriminate the geographical origin of 6 cultivars originating from the four main growing regions (namely Chile, Georgia, Italy and Turkey). This approach allowed annotating more than 1000 compounds among polyphenols and sterols. The metabolomics data were elaborated with both unsupervised (hierarchical clustering) and supervised (Orthogonal Projections to Latent Structures Discriminant Analysis, OPLS-DA) statistics. These multivariate statistical tools allowed to discriminate hazelnut samples considering both 'cultivar-type' and 'geographical origin'. In particular, flavonoids (anthocyanins, flavanols and flavonols - VIP scores 1.34-1.49), phenolic acids (mainly hydroxycinnamics - VIP scores 1.35-1.55) together with cholesterol, ergosterol and stigmasterol derivatives (VIP scores 1.34-1.49) were the best markers to discriminate samples according to the geographical origin. CONCLUSIONS: This work outlines the potential of untargeted profiling of phenolics and sterols based on UHPLC-ESI/QTOF mass spectrometry to discriminate hazelnut and support authenticity and origin.