Volatilome Characterization of the Flat White Onion of Fara Filiorum Petri (Allium cepa L.) and Its Differentiation from Other Italian White Onions by HS-SPME-GC-MS

The Flat White Onion of Fara Filiorum Petri is a traditional Italian landrace that represents the agrobiodiversity and gastronomic heritage of the Abruzzo region. However, its volatile composition has not yet been characterized. In this study, the volatile profile of 31 samples of Flat White Onion of Fara Filiorum Petri and other (53) Italian white onions was investigated by headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS). A total of 51 volatile organic compounds (VOCs) were tentatively identified as characteristic of onion aroma. Principal component analysis (PCA) revealed a characteristic volatilomic fingerprint for the Flat White Onion of Fara Filiorum Petri and highlighted a high degree of consistency between the two harvest years, indicating that seasonal variability mainly affected the relative abundance of selected VOCs while preserving the overall volatile profile. Authentication was subsequently investigated using Soft Independent Modeling of Class Analogy (SIMCA). The optimal model correctly recognized 88.9% of Fara samples in the external test set while rejecting all non-Fara onions, achieving 100.0% specificity. These findings demonstrate that HS-SPME-GC-MS combined with chemometric analysis provides an effective approach for the characterization and authentication of the FlatWhite Onion of Fara Filiorum Petri, supporting the conservation of this Italian landrace.