TIME-COURSE OF ASTRINGENT SENSATIONS

Qualitative and quantitative perceptual reactions to astringent materials were examined for three diverse chemical substances (alum, tannic acid and tartaric acid) at several concentrations producing moderate to strong levels of perceived sensation. Group discussions were held to determine language appropriate to describe the sensations arising from solutions of the three compounds and a composite ballot of six rating scales (astringency, mouth drying, puckery feeling, mouth roughing, bitterness and sourness) was developed. For both experiments, two concentrations of each compound were rated on the six attributes for five to six minutes, a discrete-point time - intensity scaling procedure. All ratings showed roughly exponential decays over time. The intensity ratings for each attribute were found to depend on both the particular astringent substance and concentration tested. The results from experiment 2 suggested that the four tactile attributes of drying, puckery feeling, roughing, and overall astringency may not be totally interchangeable and that there may be multiple sub-qualities in the sensory reactions grouped as astringency. It is recommended that future structure - activity studies make use of time - intensity procedures with multiple rated attributes, using 1 g/l alum as a reference material, since it is relatively low in perceived bitterness and sourness, but produces pronounced drying, roughing, puckery/drawing sensations.