Taste interaction between glucose and fructose assessed by functional measurement.

Abstract

The description of the sensory interaction between two taste substances in terms of numerical responses obtained under a magnitude estimation instruction is biased, because the sensory processes are confounded with the judgmental process. Because the judgmental process is irrelevant to the sensory processes involved in the perception of taste substance mixtures, a correct description of mixture interaction can be obtained only with an experimental setup that separates the sensory processes from the judgmental process. Functional measurement in combination with a two-stimulus procedure can separate these two mechanisms. When this approach is used, parallelism in the factorial plot of the responses depends not on the underlying sensory processes, but on the comparative operation between two sensory impressions and on the form of the judgment function. In this experiment, solutions of glucose, three equiratio mixture types of glucose and fructose (i.e., mixtures in which the ratio of the components is constant), and fructose were compared with glucose solutions for sweetness intensity. Under the assumption that the comparative operation between two perceived sweetness intensities is subtractive, this scaling procedure yields interval scales of perceived sweetness intensity. The results showed that the data obtained are reliable, and that the psychophysical functions for equiratio mixtures of glucose and fructose lie in between the psychophysical functions for unmixed glucose and fructose.