Effect of Miraculin on Sweet and Sour Tastes Evoked by Mixed Acid Solutions

Abstract

Miraculin is a glycoprotein, and it changes the perceived quality and intensity of tastes (especially, sourness and sweetness). The oral application of miraculin in a high concentration elicits a strong sweetness for sour tastants. However, the mixing of different tastants increases or decreases the intensity of the taste elicited in comparison with the intensities elicited by the individual sour tastants. The synergy between different (e.g., sweetness and sourness) or similar taste qualities can be responsible for the changes in the perceived taste intensities. Despite the characteristics of miraculin and the sour tastant mixtures, the effects of miraculin on mixed acid solutions are still unknown. The goals of this study were to assess the following: 1) the intensities of the sourness and sweetness of mixed acid solutions before and after the oral application of miraculin and 2) the intensity of the sweetness of the mixed acid solutions after the oral application of miraculin. For twenty healthy young adults, sensory evaluation experiments examined the perceived intensities of taste (sweetness, sourness, and astringency) and the overall odor of six organic acid solutions (2.3 × 10 – 2 M of citric acid and three-binary and two-trinary mixtures including citric acid that ranged from 2.24 to 2.48 in average pH). The application of miraculin elicited sufficient sweetness, but it did not show statistically significant differences in the intensities of sweetness among the six acid solutions. Except for the sweetness, all of the four sensory items exhibited significant changes among the six solutions both before and after the application of miraculin, while the average scores for these items did not correlate with the average solution pH values. These results suggest that the binary and trinary mixed acid solutions affect the sourness both before and after the oral application of miraculan; however, there was no effect on the sweetness.