Abstract
The change in sensitivity to gustatory stimulation induced by an extract of Gymnema sylvestre, R. Br., one of the taste modulators, was studied. The taste sensitivity for sweet, sour, salty, bitter, and umami substances was examined before and after the application of a Gymnema sylvestre extract. A concentration of the extract not disliked by the taste panel was selected. Twenty-seven compounds, including mono-and disaccharides, oligosaccharides, sugar alcohols, and peptides, were used as sweet substances. The panelists were 28 healthy female students between the ages of 18 and 20. The taste sensitivity was examined by a method whereby each compound was applied in a sequence of decreasing concentration to the entire oral epithelium of individual panelists. The minimum perceptible concentration (taste threshold) of each taste substance is defined as the concentration at which 50% of the subjects could barely differentiate a solution containing the taste substance from water, and was calculated by the probit analysis. The minimum taste-perceptible concentrations of all 27 sweet substances was increased 2-13-fold after the application of a Gymnema sylvestre extract. This marked increase in minimum perceptible concentration after application of the Gymnema sylvestre extract was found not only for traditional sweet substances, but also for those more recently developed. However, the minimum taste-perceptible concentration was not significantly changed in one each of the sour, salty and bitter substances and in three umami substances by the application of the Gymnema sylvestre extract. The results of this study show that, after the application of a Gymnema sylvestre extract, solutions of sweet substances at a concentration less than certain limits produced a sensation similar to the taste of pure water as previously reported. At higher concentrations, however, these substances produced a sweet taste even after application of the extract. The application of the Gymnema sylvestre extract did not affect the minimum taste-perceptible concentration of the sour, salty, bitter, and umami substances.
