Influence of Sourness on Higher Brain Functions

We investigated whether change of emotion related to sourness during chewing causes higher brain functions by using mental arithmetic test. Subjects comprised 120 healthy individuals. The mental arithmetic test was performed under four conditions: chewing lemon-flavored gum (Standard gum, as a delicious gum); gum with 6 times the citric acid component of the Standard gum (Strong-sour gum, as an unpleasant gum); the Standard gum with citric acid component removed (Without-sour gum); and no chewing (Control). After chewing gum, subjects completed a subjective sensory evaluation about taste and deliciousness. The number of answers was lowest while chewing Without-sour gum compared to chewing the other gums or control. No significant correlation was found between performances of the mental arithmetic test and subjective sensory evaluation, except for a weak negative correlation with taste. These results suggest that the sourness might have influence on higher brain functions.