Many studies have reported that subjective taste intensity is enhanced by odors which are congruent, for example a sweet taste and a vanilla odor. Some reports have suggested that subjective taste is more strongly enhanced by retronasal than by orthonasal odors; others have suggested that taste enhancements by both odor routes are identical. Differences between the two routes include the direction of airflow accompanying breath. Although we have already reported the enhancement of a sweet taste induced by a vanilla odor, the enhancement of a salty taste has not been reported. Here, we examined whether the enhancement of a salty taste is induced by a soy sauce odor synchronized with breathing. The results of this study, in which olfactory stimuli were presented synchronously with breathing in, demonstrate that a retronasal soy sauce odor after drinking enhanced a salty taste, but an orthonasal soy sauce odor before drinking did not.
