Distribution of Odorant Compounds in Recirculating Aquaculture Systems Used in Sturgeon Farming

This study investigated the distribution of odorant compounds in water collected from the tank, drum filter, biological filter, and UV system outlets and the sludge inside the drum filter across two sturgeon RAS farms. A combinatory sensory-analytical approach was applied to assess the aroma profiles via descriptive sensory analysis and the odorant composition by gas chromatography–olfactometry and gas chromatography–mass spectrometry. All water samples were described as fishy, moldy, earthy, algae-like, and sea-water-like notes. Eighty-six odorants were detected olfactorily, of which 44 were identified. Notably, several compounds are reported here for the first time in RAS water, including 1-butanol, myrcene, 1-tetradecene, γ-crotonolactone, 2,6-di-tert-butyl-4-methylphenol, 2-phenoxyethanol, ethyl palmitate, methyl stearate, and methyl dihydrojasmonate. Geosmin and 2-MIB were quantified in all samples. Their concentrations varied from 85 to 432 and from 40 to 43 ng/L for RAS 1 and from 70 to 178 and from 60 to 82 ng/L for RAS 2, respectively. The concentration of both compounds did not vary through the compartments due to water recirculation, and a high concentration was only detected in water from the sludge.