Sensory Evaluation of the Off-Flavors Geosmin and 2-Methylisoborneol (MIB) in Farm-Raised Catfish

Individuals responsible for tasting catfish in quality control settings sometimes report sensations of sensory adaptation, sensory fatigue and flavor carry-over between samples containing earthy/muddy off-flavors due to geosmin and/or 2-methylisoborneol (MIB). If these experiences are real, sensory evaluation of flavor quality may not be as straightforward as many fish processors and researchers would wish. To determine the influence of these compounds on the sensory evaluation of fish, a series of controlled experiments was conducted. These studies indicate that trained panelists were unable to recognize and evaluate, with precision, the intensity of off-flavor compounds such as geosmin and MIB. However, panelists were precise in evaluating other natural off-flavors, such as fishy. In evaluating two MIB samples in succession, the second sample was perceived as having a lower MIB intensity. The addition of off-flavor compounds to catfish caused the panelists to perceive the desirable flavor chickeny to be...