Impact of pulsation rate and viscosity on taste perception - Application of a porous medium model for human tongue surface

Abstract

Background: Temporal dynamics may importantly modulate sensory perception, including taste. For example, enhanced perceived taste intensity is often observed when tastant concentration is fluctuating in pulses. The perceived intensity is higher than that of the solutions with a same averaged, but constant concentrations. Meanwhile, taste intensity often decreases with increase of tastant viscosity, despite no changes to the stimuli concentration. The mechanisms to these phenomena are not well understood, in part due to the complicated transport process of tastant through papillae, taste pores, etc. to reach the taste receptors, a cascade of events that are difficult to quantify.

Method: We computationally modeled the human tongue surface as a porous micro-fiber medium, extending a previous study and exposed it to pulsatile tastant solution (0.2 and 0.4Hz) with various added viscosity (~0.0011-~0.09 Pa⋅s).

Results: Our simulation revealed that the stimuli concentration within the papillae structure increase with pulsed stimulation, especially those with a longer period (16% increase at 0.4Hz and 23% at 0.2Hz compared to continuous stimuli) and decrease (-6%) with added viscosity. The trend matched well with measured taste perception to sucrose added apple juice in the literature (R² > 0.97 for both low and high viscosity stimuli series). Decreased diffusivity due to the increase in viscosity, however, was not a major factor underlying this process.

Conclusion: This study re-affirms the validity and accuracy of modeling human tongue surface as a porous medium to investigate taste stimuli transport processes and such peripheral transport dynamics may have significant effects on taste perception.

Keywords: Complex flow; Papillae; Porous media; Pulsatile stimulation; Taste perception.