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Off- flavour problems in farmed trout (TRT13) - FC0917

Summary Objective:-
To identify the organisms that cause off-flavors (taints) in trout and investigate the biological and environmental mechanisms that promote them. Develop tolls to predict early detection thus enabling taint mangement strategies to be developed.

Key Customer Purpose:-
Off-flavours, charactorised by a destinctive earthy/muddy odour and taste have a large economic impact on the markability of farmed trout. This research may lead to better preventive measures or alternative treatment strategies.
The project has five specific objectives:

1. To identify the causative organism(s) and the factors - environmental or otherwise - that promote their production
We wish to discover whether there is a single causative organism or whether several different organisms are involved. We also wish to determine the environmental factors that promote the proliferation of such nuisance algae and the relative roles of species/strain and environment in taint compound production.

2. To increase understanding of the mechanisms by which taint compounds are produced and released into the water and to elucidate pathways of uptake and excretion by fish
To determine whether taint compounds are produced by certain species or strains or stages in the life cycle of the organisms or whether they are only produced in any quantity during periods of nutrient/physical (temperature, flow) stress. We also wish to discover whether taint compounds are actively secreted or only released into the water on death of the organism. We wish to confirm that uptake of taint compounds is passive and that the main route of uptake is via the gills rather than through the food web or adsorbtion of taint compounds onto pelleted feed. The effects of concentration in the water, duration of exposure and temperature on taint compound dynamics in fish tissues will be determined.

3. To correlate organoleptic with quantitative measures of off-flavour compounds
There is no information correlating the presence of taint compound in fish tissues with organoleptic (odour; taste) properties of farmed trout prepared in different ways. Taint problem threshold concentrations remain to be determined.

4. To develop predictive tools and enable early detection
Data on taint compound production in relation to environmental conditions will be combined with data on uptake of compound and turnover dynamics to try to provide and early-warning system.

5. To optimise taint problem management strategies
The efficacy, practicality and cost-effectiveness of various treatment methods, including filtration, ozonation, photocatalysis and aeration, will be explored. Data from laboratory/tank trials on tissue turnover rates will be combined with those from organoleptic trials to optimise depuration strategies.
Project Documents
• Final Report : Off flavour problems in farmed trout: identification of causative organisms and development of management strategies   (295k)
Time-Scale and Cost
From: 2000

To: 2003

Cost: £101,628
Contractor / Funded Organisations
University - Robert Gordon
Fish Farming              
Fields of Study
Fish Health and Aquaculture