Interactions between oral chemical irritation, taste and temperature

Abstract

The oral chemical irritant, capsaicin, at 2, 4 and 8 p.p.m., was combined in mixtures with sucrose (Experiment 1), sodium chloride (Experiment 2) and soup (Experiment 3), each evaluated at two temperatures. These mixtures were rated for their sweetness and/or saltiness, intensity of burning sensation and total mixture intensity. In both solution and soup, sweetness was suppressed, whereas saltiness showed only minor suppression in low NaCl, high capsaicin mixtures. The burning sensation produced by capsaicin was uninfluenced by sucrose, while NaCl increased the burning sensation. Total mixture intensity was entirely determined by capsaicin concentration in mixtures with sucrose, although NaCl contributed in NaCl/capsaicin mixtures. Varying temperature influenced the burning sensation and total intensity of sucrose/capsaicin mixtures, but did not modulate the effects of capsaicin on taste. Explanations of taste suppression in terms of cognitive and structural models are examined. The differential effect of capsaicin on sweetness and saltiness is also considered in terms of the irritant properties of NaCl.