Depuration of geosmin- and 2-methylisoborneol-induced off-flavors in recirculating aquaculture system (RAS) farmed European whitefish Coregonus lavaretus

P C Lindholm-Lehto,H Pakkanen,R Alén,J Vielma

doi:10.1007/s13197-019-03910-7

P C Lindholm-Lehto, H Pakkanen + Show 2 more

Open Access

https://doi.org/10.1007/s13197-019-03910-7

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Abstract

European whitefish Coregonus lavaretus has increasingly become an important species for aquatic food production, especially in the Nordic countries. Whitefish is produced in traditional cage and pond operations, and in recirculating aquaculture system (RAS) in which, unfortunately, off-flavors and odors, mostly caused by geosmin (GSM) and 2-methylisoborneol (MIB), can accumulate in fish flesh from the circulating water. GSM and MIB have very low human sensory detection limits and, therefore, often disliked by consumers even at low concentrations. In this study, concentrations of GSM and MIB in RAS farmed European whitefish were studied by an analytical method based on headspace solid phase microextraction and gas chromatography–mass spectrometry. Concentrations were determined in different parts of fish: fillet, neck, belly, and tail during a depuration period and in depuration water. The highest initial concentrations were on average 32 ng g−1 (GSM) and 24 ng g−1 (MIB) in European whitefish fillet and 128 ng L−1 (GSM) and 94 ng L−1 (MIB) in water, respectively. After a depuration period of 16 days, concentrations decreased to below the detection limits, indicating the importance of the depuration period.

Highlights

Aquaculture has been a rapidly growing food producing sector and nowadays accounts for more than half of the fish used for human consumption (FAO 2016)
Manual solid phase microextraction (SPME) assembly with an extraction fiber coated with StableFlex divinylbenzene/carboxene/polydimethyl siloxane (DVB/CAR/ PDMS), 1 cm, 50/30 lm in a manual holder were purchased from Supelco (Merck)
GSM and MIB were extracted from the sample matrix by headspace solid phase microextraction (HS-SPME), modified from the method reported by Peng et al (2014)

Summary

Introduction

Aquaculture has been a rapidly growing food producing sector and nowadays accounts for more than half of the fish used for human consumption (FAO 2016). In recirculating aquaculture systems (RAS), unwanted offflavors with unpleasant odors can accumulate in circulating water and in fish flesh (Hathurusingha and Davey 2014; Houle et al 2011; Howgate 2004). Even low concentrations in water can be absorbed by fish and accumulated in lipid-rich tissues (Houle et al 2011; Howgate 2004), giving an unpleasant taste and odor to water (Smith et al 2002) and fish (Howgate 2004) Both compounds are perceived at very low concentrations (\ 1 ng g-1) by human senses (Davidson et al 2014; Robertson et al 2005). Aim of this research was to extensively study the location of off-flavor accumulation in fish flesh and the time required for sufficient depuration

Materials and methods

Method validation

Results and discussion

Conclusion