Feasibility study of Field Asymmetric Ion Mobility Spectrometry (FAIMS) for rapid off-flavor detection in recirculating aquaculture system cultured Atlantic salmon

This study evaluates the feasibility of a portable Field Asymmetric Ion Mobility Spectrometry (FAIMS) system for detecting geosmin-related off-flavors in Atlantic salmon ( Salmo salar ) fillets from fish cultured in a recirculating aquaculture system. Salmon were exposed to a concentrated geosmin solution to spike off-flavor concentration in the fish tissues, followed by purging to create varying geosmin levels. Baseline geosmin and 2-methylisoborneol (MIB) in water and fillet samples were quantified using solid-phase microextraction coupled with gas chromatography-mass spectrometry (GC-MS). Volatile organic compound (VOC) fingerprints from geosmin-treated cold and heated fillet samples were analyzed via FAIMS, and the results were compared against the untreated control (UTC). For cold samples, the VOC signatures in FAIMS spectra of the UTC and treatment groups with spiked off-flavor were nearly identical. Heated samples, however, displayed distinct ion current profiles within the compensation voltage range of −2–2 V across the full dispersion field range. Principal component and statistical analysis also demonstrated evident separation between UTC and treatment groups. While FAIMS showed promise in effectively differentiating the VOC fingerprints between UTC and geosmin-treated fish fillets, the system could not consistently distinguish concentration differences within treatment groups, regardless of thermal treatment. Overall, the sampling and pre-processing protocols developed in this study can help fish farmers quickly identify geosmin-contaminated batches during grow-out stages and prior to processing, enabling timely corrective actions. Future studies could focus on training FAIMS for the quantitative analysis of off-flavor compounds, utilizing key biomarkers identified by GC-MS.