Exploring odorant compounds in recirculating aquaculture systems‐grown fish: from earthy off‐odours to marine fragrances.

Recirculating aquaculture systems (RAS) represent the most advanced land-based and controlled-environment aquaculture farming systems and offer increased economic viability for aquaculture businesses by enhancing production efficiency and minimizing environmental impact (Abd El-Hack et al., 2022).Despite these strengths, ensuring high-quality seafood flavour from RAS remains challenging due to the presence of offodour compounds, like "earthy" geosmin and 2-methylisoborneol (2-MIB), which can diminish palatability and reduce consumer demand for RAS products (B.C. Jones et al., 2022).In the last three decades, scientific effort has been directed towards understanding and mitigating the presence of bacteria lineages responsible to generate waterborne compounds absorbed in seafood.Few recent studies correlated off-odour taints in aquaculture feeds and fish, suggesting their potential absorption through ingestion (Mahmoud et al., 2018;Podduturi et al., 2017).The present work utilized sensory evaluations combined with analytical methods (solvent assisted flavour evaporation (SAFE) technique, gas chromatography-mass spectrometry/olfactometry (GC-MS/O), aroma extraction dilution analysis (AEDA), proton transfer reaction-time of flight-mass spectrometry (PTR-TOF-MS), stable isotope dilution analysis (SIDA)) to explore correlations between exogenous volatile organic compounds (VOC) sources in several RAS-reared fish species.Three experiments were conducted to investigate the origins and pathways of absorption and accumulation of off-odour compounds.The first trial compared waterborne and feed-borne odours in RAS-raised Russian sturgeon (Acipenser gueldenstaedtii), determining the prevalent influence of RAS water odours and the absorption of VOCs from commercial feeds.Subsequently, the absorption, accumulation, and transformation of waterborne geosmin was quantified in Rainbow trouts (Oncorhynchus mykiss) fillets, blood, and liver, refining existing models of absorption (Howgate, 2004;Schram et al., 2018).Lastly, a dose-response feeding trial was conducted using an experimental algae-based aquaculture feed to enhance marine odours in RAS-grown Atlantic salmon (Salmo salar) and assess the potential to mitigate "earthy" off-odours (B. Jones et al., 2016).This research project offers valuable insights and strategies for mitigating off-odours in aquaculture seafood, enhancing the flavour quality, and optimizing cost-efficiency in RAS production.