Prospective exploration of hazelnut’s unsaponifiable fraction for geographical and varietal authentication: A comparative study of advanced fingerprinting and untargeted profiling techniques

This study compares two data processing techniques (fingerprinting and untargeted profiling) to authenticate hazelnut cultivar and provenance based on its unsaponifiable fraction by GC–MS. PLS-DA classification models were developed on a selected sample set (n = 176). As test cases, cultivar models were developed for “Tonda di Giffoni” vs other cultivars, whereas provenance models were developed for three origins (Chile, Italy or Spain). Both fingerprinting and untargeted profiling successfully classified hazelnuts by cultivar or provenance, revealing the potential of the unsaponifiable fraction. External validation provided over 90 % correct classification, with fingerprinting slightly outperforming. Analysing PLS-DA models’ regression coefficients and tentatively identifying compounds corresponding to highly relevant variables showed consistent agreement in key discriminant compounds across both approaches. However, fingerprinting in selected ion mode extracted slightly more information from chromatographic data, including minor discriminant species. Conversely, untargeted profiling acquired in full scan mode, provided pure spectra, facilitating chemical interpretability.

This work was developed in the context of the project TRACENUTS, PID2020-117701RB100 financed by MCIN/AEI/https://doi.org/10.130 39/501100011033. B. Torres-Cobos thanks the Spanish Ministry of Universities predoctoral fellowships FPU20/014540. B. QuintanillaCasas thanks the Fundacion ´ Alfonso Martín Escudero for the research grant for universities and centers abroad 2022. A. Tres received a Ramon y Cajal grant (RYC-2017-23601) funded by MCIN/AEI/https://doi. org/10.13039/501100011033 and by “ESF Investing in your future”. INSA-UB Maria de Maeztu Unit of Excellence (Grant CEX2021- 001234-M) funded by MICIN/AEI/FEDER, UE. The authors would like to express their gratitude to Ferrero Hazelnut Company and Tuscia University (Department of Agriculture and Forest Science) for providing the hazelnut samples from Chile and Italy, respectively.

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