Binary taste mixture interactions in PROP non-tasters, medium-tasters and super-tasters

it is generally assumed that the mutual, but asymmetric, suppression of the components in binary taste mixtures is an invariant property of the human psychophysical response to such mixtures. However, taste intensities have b een shown to vary as a function of individual differences in sensitivity, i ndexed by the perceived bitterness of 6-n-propylthiouracil (PROP). To deter mine if these variations in taste perception influence taste mixture intera ctions, groups of PROP super-, medium- and non-tasters assessed four binary taste mixtures: sweet-bitter [sucrose/quinine hydrochloride (QHCl)], sweet -sour (sucrose/citric acid), salty-bitter (NaCl/QHCl) and salty-sour (NaCl/ citric acid). In each experiment, subjects received factorial combinations of four levels of each of two tastants and rated individual taste intensiti es and overall mixture intensity. For each taste quality, super-tasters typ ically gave higher ratings than either medium- or non-tasters, who tended n ot to differ. There were also group differences in the interactions of the mixtures' components. Super-tasters rated the overall intensity of the mixt ures, most likely reflecting integration of the taste components, as greate r than medium- and non-tasters, who again showed few differences. in sweet- bitter mixtures, nor-tasters failed to show the suppression of sweetness in tensity by the highest QHCl concentration that was evident in super- and me dium-tasters. These data show that the perception of both tastes and binary taste mixture interactions varies as a function of PROP taster status, but that this may only be evident when three taster groups are clearly disting uished from one another.