Abstract
IntroductionTaste perception is affected by trigeminal stimuli, i.e., capsaicin. This has been studied at suprathreshold concentrations. However, little is known about taste perception at threshold level in the presence of low concentration of capsaicin. The aim of the study was to explore whether taste sensitivity for sweet, sour, salt, bitter, and umami is modulated by the presence of capsaicin in the peri-threshold range.MethodsFifty-seven adults (age range 19–85 years; 32 women) with functional gustation participated in the study. Based on their perception of phenylthiocarbamide (PTC), the group was stratified into non-tasters (n = 20) and tasters (n = 37). Threshold for sweet (sucrose), sour (citric acid), salty (sodium chloride), bitter (quinine-hydrochloride), and umami (sodium-glutamate) tastes was estimated using a single-staircase paradigm (3-alternative forced choice; volume per trial 0.1 ml) with or without 0.9-µM capsaicin added. This capsaicin concentration had been determined in pilot studies to be in the range of oral perception thresholds.ResultsThe addition of capsaicin produced lower taste thresholds for sweet, sour, salty, and bitter but not for umami. In contrast, neither PTC taster status nor sex affected these results.ConclusionThe current results indicate that a low concentration of capsaicin increases gustatory sensitivity.ImplicationsThe current findings provide evidence supporting different effects of capsaicin on taste perception at threshold level. It has implications for boosting taste sensitivity or flavor enjoyment with low concentration of capsaicin.
Highlights
Taste perception is affected by trigeminal stimuli, i.e., capsaicin
The ancillary tests showed that there was a weak but significant effect of oral capsaicin pretreatment on taste sensitivity (Fig. 2) (F(1,9) = 5.13, p = 0.049); none of the taste qualities survived the significant threshold after correction for multiple comparisons
Results from the current study showed that a low concentration of capsaicin increased taste sensitivity by lowering the recognition thresholds
Summary
Taste perception is affected by trigeminal stimuli, i.e., capsaicin. This has been studied at suprathreshold concentrations. Threshold for sweet (sucrose), sour (citric acid), salty (sodium chloride), bitter (quinine-hydrochloride), and umami (sodiumglutamate) tastes was estimated using a single-staircase paradigm (3-alternative forced choice; volume per trial 0.1 ml) with or without 0.9-μM capsaicin added This capsaicin concentration had been determined in pilot studies to be in the range of oral perception thresholds. Implications The current findings provide evidence supporting different effects of capsaicin on taste perception at threshold level It has implications for boosting taste sensitivity or flavor enjoyment with low concentration of capsaicin. Another study showed that the presence of sweet taste decreases capsaicin irritation by approximately 50%, and the effect can be partially reversed by adding a sweet taste inhibitor (lactisole) (Smutzer et al 2018) This results indicate that the effect of sucrose on capsaicin perception is mediated by the sweet taste receptor (Smutzer et al 2018). The co-localization of capsaicin receptors (vanilloid receptor subtype 1) with sweet or bitter taste receptors has been found in rat (Moon et al 2010) and human (Jahng et al 2010) taste papillae
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