Chemical taste taint accumulation in RAS farmed fish - A Fr 13 risk assessment demonstrated with geosmin (GSM) and 2-methylisoborneol (MIB) in barramundi (Lates calcarifer)

- Natural fluctuation in chemicals in RAS water can cause taint accumulation in fish.
- Critical conditions identified for RAS barramundi (Lates calcarifer).
- Approach used to assess vulnerability to taste taint and to improve RAS reliability.
- Results applicable to range of fish species.
- Immediate benefit to researchers and risk analysts in foods processing.

Recirculating Aquaculture System (RAS) farming of fish is becoming widespread. However, taste taint accumulation in the fish flesh as geosmin (GSM) and/or 2-methylisoborneol (MIB) is a major concern for farmers and consumers. Here we apply the emerging Fr 13 risk methodology (Food Control 50 (2015) 770-777; Food Control 29 (2013) 248-254) to demonstrate quantitatively the impact of naturally occurring fluctuations in these chemicals in RAS water on their accumulation in fish flesh. The approach is based on the time dependent accumulation model of Hathurusingha and Davey (Ecological Modelling 291 (2014) 242-249) in which taint chemicals enter the flesh via the gills and are diluted through metabolism and growth, together with a risk factor (p) such that for all p > 0 the chemical taint is above a desired threshold concentration (which includes a practical tolerance) respectively, 0.814 and 0.77, μg kg−1 for GSM and MIB. Monte Carlo (with Latin Hypercube) sampling of chemical in the growth water (CW), water temperature (T) and growth time (t) was used to simulate practical RAS farmed barramundi (Lates calcarifer), a premium fish, for up to 260 days growth. Results show some 10.10% of all harvests over the long term will result in fish with taste taint as GSM above the threshold concentration due to natural fluctuations in the RAS environment. For MIB this failure rate is 10.56%. The vulnerability to taste taint failure is shown to be impacted highly significantly by the time to harvest, and to a lesser extent by concentration and fluctuation of the taint chemicals in the RAS water. An advantage is growth time can be readily controlled by farmers; this should not exceed 240 day. The methodology appears generalizable and therefore applicable to a range of RAS farmed foods. Findings will be of immediate benefit to RAS farmers and to risk researchers in foods processing.