SENSORY ANALYSIS OF TROUT TAINTED BY DIESEL FUEL IN AMBIENT WATER

Rainbow trout (Salmo gairdneri) were kept in fresh water tanks for 24 h and exposed to one of seven concentrations of diesel, using a flow-through system with used water discharged to waste. The concentrations ranged from 0.0087 to 0.87 mg.l-1 (0.01 to 1.0 mu-l.1(-1). An experienced taste panel assessed the degree of taint in the cooked fish by four different procedures. These were the triangular test, three-alternative forced-choice (3-AFC) and two forms of rating scale. The triangular and 3-AFC procedures yielded similar estimates of threshold, the estimate from the combined data being approximately 0.08 mg.l-1. Although the 3-AFC procedure has some advantages, they are not sufficient to recommend it in place of the triangular test. Both methods showed better ability to discriminate low levels of taint than the quantitative rating procedures.