Random presentation minimizes the effect of expectation on the Hedonic Threshold Methodology

Abstract The expectation error occurs when the evaluator has previous information about the test and/or product and detects attributes/differences based on this knowledge. This can happen in the Hedonic Threshold Methodology (HTM): consumers can start to recognize the stimulus and become more critical in subsequent evaluations. In the original protocol, in the first acceptance test sessions, the stimulus samples most similar to the control are presented and the intensity is progressively changed until the last session. A possible way to minimize this effect may be the random presentation, therefore, the aim of this study was to investigate whether the values of the hedonic thresholds are altered by the random presentation of the stimulus samples. For this, HTM was applied to reduce sucrose in grape nectar, using 120 consumers for each protocol: “similar to different” (from the stimulus most similar to the control to the most different), “different to similar” (from the sample stimulus more different from the control to the more similar) and random (for each consumer). The “different to similar” protocol is not recommended, as it results in inaccurate hedonic thresholds, due to fatigue or sensory adaptation. The “similar to different” and random protocols can be used, as they make it possible to obtain accurate thresholds. However, the random protocol was the one that resulted in more accurate thresholds, probably due to the minimization of expectation, which may be desirable or undesirable, depending on the application. It is suggested that, for the other threshold methodologies, random presentation could be used, however, further studies are required to confirm.