Effects of taste quality and intensity on oral perception of viscosity.

Abstract

Oral assessments of viscosity were obtained with the method of magnitude estimation. Subjects judged the viscosity of a series of aqueous solutions thickened to one of six viscosity levels (1–2025 centistokes) with a food-grade gum, sodium carboxymethylcellulose. The solutions contained one of several concentrations of caffeine, citric acid, sodium chloride, or sucrose. The presence of taste substances significantly altered the perception of solution viscosity for only the thickest solutions. Increasing concentrations of citric acid and sodium chloride produced progressive decreases in perceived viscosity, and increasing sucrose concentrations produced small increases in perceived viscosity. Caffeine did not affect judgments of solution viscosity. The most likely explanation for these findings is that subjects detected differences in the Newtonian behavior of the thickened solutions, differences that were produced by the addition of taste substances.