Changes in chorda tympani nerve responses and preference for sodium chloride mixed with thickeners

Sodium chloride (NaCl), an important mineral for human homeostasis, is perceived by taste receptors. The objective of this study was to investigate how perceived intensity and preference for NaCl by taste receptors were affected after mixing with thickeners in electrophysiological and behavioral experiments in Wistar/ST rats.

Chorda tympani nerve responses to 0.1 M NaCl, 0.1 M sucrose, 3 mM hydrochloride, and 1 mM quinine hydrochloride, with and without thickeners, were measured by electrophysiology. Commercially available grades of 3% xanthan gum-based (X), 2% guar gum-based (G), and 4.7% starch-based (S) thickeners were used. To investigate the effect of thickener concentration, responses to 0.1 M NaCl mixed with 1%, 2%, and 3% X were measured. A two-bottle preference test and a brief-access test were performed using the following stimuli: 0.1 M NaCl, distilled water, and their mixture with one of the three thickeners.

The degree of suppression varied depending on taste stimuli and thickeners; however, in most instances, chorda tympani nerve responses to the tested taste stimuli were suppressed by mixing with thickeners. The response and preference for 0.1 M NaCl were suppressed by mixing with X and G. The brief-access test demonstrated that the suppression was caused by the taste effect.

Mixing thickeners, such as X and G, but not S, with NaCl, suppressed perceived intensity and preference for NaCl.