Elucidation of a potential detection mechanism for high-viscosity solutions in the oral cavity using tissue isolation and anatomical characterization

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Studies on viscosity and its oral perception are limited to relatively thin viscosities (η<3000cP), thinner than many relevant food products. Moreover, multiple modelling studies indicate perception of high-viscosity solutions is linked to filiform papillae deformation, but this has yet to be tested psychophysically. This study sought to characterize the detection mechanism underpinning perception of high-viscosity (η>3000cP) solutions. We hypothesized the tongue would be chiefly responsible for viscosity perception, due to its active role in product manipulation, and that discrimination ability of high-viscosity solutions would be linked to filiform papillary attributes. Just-noticeable difference (JNDs) thresholds for viscosity were determined for participants (n=59) using the forced-choice staircase method for glycerin/water/carboxymethyl cellulose solutions (η=4798-12260cP). Participants evaluated solutions by pressing them against the hard palate in "palate-blocked", "tongue-blocked", and "unblocked" conditions. Optical profiling was then used to characterize papillary structures in tongue biopsies of a subset of participants (n=45). Papillary attributes were related to "palate-blocked" performance using causal analysis. Participants' differentiations were significantly better (p<0.001, both) using the whole oral cavity (JND=1041.71cP±50.36cP) than using tongue (JND=1671.26cP±142.77cP) or palate (JND=1791.42cP±117.42cP) alone. There was no significant difference between the blocked conditions (p=0.724), and performance in those conditions was not significantly correlated (p=0.773). "Palate-blocked" data significantly correlated to filiform papillae length and density (p<0.001, and p=0.005, respectively). Variation in these attributes alone explained variation in "palate-blocked" JND (p<0.001). Results from psychophysical tests run counter to the original hypothesis, suggesting the tongue and palate play equal roles in viscosity perception, but individuals may differentially utilize these tissues when discriminating between solutions. Similarly, anatomical characterization of filiform papillae provides insight into the role these structures play in high-viscosity perception.


Food, Agricultural, and Environmental Sciences (FAES): 1st Place (The Ohio State University Edward F. Hayes Graduate Research Forum)


viscosity perception, texture, tongue, filiform papillae