Location: Cool and Cold Water Aquaculture ResearchTitle: Determination of off-flavor compounds, 2-methylisoborneol and geosmin, in salmon fillets using stir bar sorptive extraction–thermal desorption coupled with gas chromatography–mass spectrometry Author
Submitted to: Journal of Chromatography A
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2013
Publication Date: 10/16/2013
Citation: Ruan, E., Aalhus, J., Summerfelt, S., Davidson, J., Swift, B., Juarez, M. 2013. Determination of off-flavor compounds, 2-methylisoborneol and geosmin, in salmon fillets using stir bar sorptive extraction–thermal desorption coupled with gas chromatography–mass spectrometry. Journal of Chromatography A. 1321: 133-136. Interpretive Summary: Fish cultured in recirculating aquaculture systems (RAS) can bioaccumulate off-flavor compounds produced by certain species of bacteria. These common off-flavors are often described as “earthy” or “musty” by the consumer, and if present at high enough concentrations can result in product that is unpalatable and unacceptable for the marketplace. Therefore, it is critical for RAS facilities to have access to reliable measurement techniques for off-flavor compounds in fish and in water. A sensitive and solvent-less method to quantify off-flavor concentrations in salmon tissue was developed. The method can be applied to detect off-flavor compounds at very low concentrations while using significantly smaller amounts of tissue sample. The number of laboratories that have the capability of effectively measuring off-flavor compounds in meats is currently limited. Development of this relatively novel technique expands the laboratory potential for analysis of off-flavor compounds in aquaculture products. Expanded access to this effective technique could allow fish farmers to assess off-flavor compounds in water and in fish in advance of harvesting and therefore fine tune environmental conditions on the farm and/or depuration protocols that ultimately could result in enhanced product quality.
Technical Abstract: A sensitive and solvent-less method for the determination of musty and earthy off-flavor compounds, 2-methylisoborneol (MIB) and geosmin (GSM), in salmon tissue was developed using stir bar sorptive extraction -thermal desorption coupled with gas chromatography -mass spectrometry (SBSE -TD -GCMS). MIB and GSM were solid phase extracted using polydimethylsiloxane (PDMS) coated stir bars, analyzed by gas chromatography, and detected in full scan mode of mass selective detector (MSD). Using this method, the calibration curves of MIB and GSM were linear in the range of 0.3 -100 ng/L, with a correlation coefficient above 0.999 and RSDs less than 4% (n = 4). The limit of detection (LOD, S/N = 3, n = 6) and limit of quantification (LOQ, S/N = 10, n = 6) of MIB and GSM were both ~0.3 and 1 ng/L, respectively. The recoveries of MIB and GSM were 22% and 29% by spike in 30 ng/L standard compounds, 23% and 30% by spike-in 100 ng/L standard compounds in salmon tissue samples with good precision (<8% of RSDs, n = 6), respectively. The recoveries of MIB and GSM were better than reported methodologies using SPME fibres (<10%) in fish tissue samples. This method was successfully applied to monitor and characterize depurated salmon fillet samples (0, 3, 6 and 10 days).