Dose–response functions and methodological insights for sensory tests with astringent stimuli

Abstract

Sensations such as bitterness and astringency can limit the acceptance of many purportedly healthy foods. The purpose of this study was to investigate dose–response relationships of various astringent and bitter stimuli in a beverage, and to simultaneously gain additional methodological insight for the effects of wording, repeated tasting, and beverage matrix on these sensations. Untrained participants were presented with samples of a “flavored beverage” or water containing various concentrations of four stimuli (alum, malic acid, tannic acid, and quinine) and were asked to rate intensities of tastes (bitterness, sourness, and sweetness) and astringency subqualities (roughing, drying, and constricting or puckering) using a generalized visual analog scale. Using constricting in place of puckering had no effect on ratings. The effects of repeated tasting and beverage matrix on astringency perception were stimulus-dependent. This study informs future investigations to understand the psychophysics of tastes and astringency. Practical applications: This study provides stimulus- and quality-specific data to improve astringency research. Furthermore, dose–response functions will aid researchers when selecting appropriate concentrations of astringent stimuli. We also provide recommendations for a variety of testing contexts, such as beverage matrix and the number of samples, to optimize the design of astringency studies, especially for naïve participants. This study further demonstrates how affective responses influence evaluation of astringent samples among untrained participants.