Control of off-flavor compounds in a full-scale recirculating aquaculture system rearing rainbow trout <i>Oncorhynchus mykiss</i>

Fish is increasingly produced in recirculating aquaculture systems (RAS), which can offer some production and environmental benefits. Unfortunately, there is a tendency to develop off-flavors in RAS, mainly caused by geosmin (GSM) and 2-methyl isoborneol (MIB) accumulating in the fish flesh from the circulating water. These off-flavors are objectionable to consumers, reducing the profitability of production and causing an unwanted reputation for this fish production sector. In this study, combinations of oxidative chemicals: ozone (O₃), hydrogen peroxide (H₂O₂), and peracetic acid (PAA) were applied in a commercial, full-scale (1.3 M kg a⁻¹) RAS rearing rainbow trout (<i>Oncorhynchus mykiss</i>). Inlet water from a nearby lake, circulating water, and depuration water were treated to increase their quality and enhance the depuration procedure. The results showed a decrease of 77% (MIB) and 93% (GSM) in the concentrations of off-flavors in circulating water after the treatments with oxidative chemicals.