Interactions among salty, sour and bitter compounds

The human gustatory system is capable of responding to and processing the taste of solitary compounds in water. However, the taste system rarely contacts solitary compounds outside the laboratory and has surely evolved to process complex mixtures of sapid chemicals, such as occur in virtually all foods. This review will focus primarily on the lesser-studied interactions between pairs of salty, sour and bitter compounds. Pair-wise interactions among these three taste qualities should be of interest because they constitute a significant proportion (similar to 30-50%) of possible binary taste interactions. In general, salts and acids enhance each other at moderate concentrations but suppress each other at higher concentrations. Bitter compounds and acids can either enhance or suppress each other depending on the concentrations, the food stimuli and the experimental methods involved. Sodium salts and bitter compounds generally interact so that bitterness is suppressed to some variable degree and the saltiness is unaffected. As will be described below, there are exceptions to all of these generalities.