Controlling of geosmin and 2-methylisoborneol induced off-flavours in recirculating aquaculture system farmed fish—A review

Abstract

Recirculating aquaculture system (RAS) is an increasingly popular alternative to open aquaculture production systems. However, off-flavours and odours can accumulate in the fish flesh from the circulating water and decrease the fish meat quality. Off-flavours are typically caused by geosmin (GSM) and 2-methylisoborneol (MIB) that are lipophilic compounds formed as secondary by-products of bacterial metabolism. Even though GSM and MIB are not toxic, they often are disliked by consumers, and both have very low human sensory detection limits. Multiple methods have been suggested to remove or decrease GSM and MIB in fish, including ozonation, advanced oxidation processes (AOP)s and adsorption removal from water using activated carbon and/or zeolites. So far, purging with fresh water is the only efficient method available to remove the off-flavours. There are multiple analytical methods available for the extraction and separation of GSM and MIB from fish flesh and water. This review discusses the current knowledge of GSM and MIB formation, the challenges faced by RAS farms due to these compounds and process solutions available for their removal.