Quantification of Oral Roughness Perception and Comparison with Mechanism of Astringency Perception.

Abstract

Texture contributes to food acceptance, but oral texture perception is incompletely understood. Presently, we quantified individual sensitivities to lingual tactile roughness and assessed the impact of age, salivary flow (SF), and fungiform papillae density (FPD) on threshold and suprathreshold perception. Additionally, we tested the hypothesis that individuals highly sensitive to tactile roughness exhibit sensitivity to astringent stimuli. Detection thresholds (DTs) were determined using the staircase method for surface roughness from stainless steel coupons (Ra; 0.177-0.465 µm) and astringency elicited by epigallocatechin gallate (EGCG; 0-1.64 mM) and tannic acid (TA; 0-0.71 mM) from 30 individuals. Suprathreshold sensitivity was assessed from intensity ratings of electroforming comparator surfaces with roughnesses ranging from 0.51 to 22.8 µm and astringent stimuli ranging from 0 to 5.2 mM (EGCG) and from 0 to 1.9 mM (TA). SF, FPD, and astringent food pleasantness scores were collected. Variability in threshold roughness sensitivity enabled dividing subjects into high (RHi; n = 16) and low (RLo; n = 14) sensitivity groups; however, no significant differences in age, FPD, or SF were observed across these cohorts. Interestingly, compared with RLo, the RHi group exhibited greater sensitivity to EGCG but not TA astringency and indicated greater pleasantness from astringent foods (e.g., unripe bananas and dark chocolate). When participants were allocated into high (SalivaHi; n = 15) or low SF (SalivaLo; n = 15) groups, TA-evoked astringency thresholds were significantly lower in SalivaHi whom also indicated greater pleasantness from astringent red wines. For suprathreshold assessments of surface roughness or astringency, no significant associations were identified with age, FPD, or SF. Suprathreshold roughness sensitivity was, however, associated with suprathreshold sensitivity to EGCG but not TA astringency.