Exploring the Relationship Between Astringency and Lingual Tactile Sensitivity

When lingual tactile sensitivity has received less attention than taste, it plays a critical role in food textural preferences and eating behavior. The anterior tongue, rich in specialized mechanoreceptors, is particularly sensitive to tactile stimuli. This study investigated inter-individual variability in lingual tactile sensitivity and its potential relationship with astringency sensitivity. To this end, three distinct aspects of lingual tactile sensitivity as well as tongue strength were assessed in 39 subjects (26 F, mean age = 35 ± 5 years). The three tactile dimensions included: (i) light touch (assessed with Von Frey monofilaments in a one-point pressure test), (ii) spatial perception (two-point discrimination test), and (iii) roughness sensitivity (using paper coupons with varying grit sizes). Astringency detection thresholds, previously determined using tannic acid solutions, were available for all participants. Results revealed significant inter-individual variability across all tactile measures. Notably, no significant correlations were found between the three different tactile sensitivity tests (light touch, spatial perception, roughness), suggesting that each one captures a distinct aspect of lingual tactile functions. Tongue strength was not associated with either tactile or astringency sensitivity. A key finding was a significant positive correlation between the tannic acid astringency detection threshold and the pressure discrimination threshold, suggesting that astringency sensitivity may involve a tactile component possibly mediated by the slowly adapting mechanoreceptors (SAI and SAII types). However, no relationship was found between astringency sensitivity and roughness sensitivity. The study emphasizes the need for standardized methods to better understand distinct dimensions of lingual tactile sensitivity and their influence on food texture perception.