Authentication and variability of Hop cones from different growing areas and harvest years via GC–MS and metal oxide sensor profiling

The volatilome comprises the set of volatile organic and inorganic compounds emitted by a biological system, reflecting its metabolic state and interactions with the environment. In agri-food matrices, changes in volatile profiles are closely linked to product quality, sensory properties, physiological stress, and biotic damage. Hop (Humulus lupulus L.) cones are particularly rich in aroma-active compounds that directly influence their commercial value and brewing performance. Therefore, monitoring volatilome evolution during cone maturation is essential to optimize harvest timing and preserve aromatic quality. Gas chromatography–mass spectrometry is the reference technique for comprehensive volatile analysis; however, it is time-consuming and not suitable for rapid or field applications. In this study, a metal oxide (MOX) sensor-based electronic nose was combined with GC–MS to investigate hop volatilome dynamics across two growing seasons and multiple cultivation sites. Sensor signals were processed through feature extraction and analyzed using Principal Component Analysis and Linear Discriminant Analysis to explore and classify maturation stages and geographical origin. The results showed clear and reproducible discrimination of samples according to maturation stage within each season, demonstrating the ability of the MOX sensor array to capture progressive changes in volatile emissions. Moreover, inter-annual variability highlighted the influence of environmental and pedoclimatic conditions on hop volatile composition. Overall, these findings confirm the robustness of sensor-based volatilome fingerprinting as a rapid and non- destructive tool for monitoring hop maturation. This approach supports the integration of electronic-nose technologies into precision agriculture, enabling scalable and efficient strategies for quality assessment and optimized harvest management.