Retronasal Intensity Research Articles

Enhancement of taste by retronasal odors in patients with Wolfram syndrome and decreased olfactory function.

Wolfram syndrome is a rare disease characterized by diabetes, neurodegeneration, loss of vision, and audition. We recently found, in a young sample of participants (mean age 15 years), that Wolfram syndrome was associated with impairment in smell identification with normal smell sensitivity and whole-mouth taste function. However, these senses were assessed separately, and it is unknown whether smell-taste interactions are altered in Wolfram syndrome, which was the focus of this study. Participants with Wolfram syndrome (n = 36; 18.2 ± 6.8 years) and sex-age-equivalent healthy controls (n = 34) were assessed with a battery of sensory tests. Using sip-and-spit methods, participants tasted solutions containing gustatory and olfactory stimuli (sucrose with strawberry extract, citric acid with lemon extract, sodium chloride in vegetable broth, and coffee) with and without nose clips, and rated perceived taste and retronasal smell intensities using the generalized Labeled Magnitude Scale. Participants also completed n-butanol detection thresholds and the University of Pennsylvania Smell Identification Test (UPSIT). Retronasal smell increased taste intensity of sucrose, sodium chloride, and coffee solutions similarly in both groups (P values <0.03). Compared with the control group, participants in the Wolfram group had lower UPSIT scores and reduced smell sensitivity, retronasal intensity, and saltiness (P values <0.03), but rated other taste intensities similarly when wearing the nose clip. Despite impairments in orthonasal smell identification, odor-induced taste enhancement was preserved in participants with Wolfram syndrome who still had some peripheral olfactory function. This finding suggests that odor-induced taste enhancement may be preserved in the presence of reduced olfactory intensity.

Intensity and Persistence Profiles of Flavor Compounds in Synthetic Solutions. Simple Model for Explaining the Intensity and Persistence of Their Aftersmell

Hydroalcoholic solutions containing a single aroma-active compound were evaluated by a sensory panel to determine the difference between ortho and retronasal odor intensities (DeltaI(ro)), buccal savoring, and aftersmell duration. Eight compounds were used. Buccal perception seems to be just a physiologically restricted form of retronasal perception. DeltaI(ro) values were dependent on the panel, although results from the two panels were significantly correlated. Such differences and the aftersmell persistence were also significantly correlated with different physicochemical parameters related to volatility. A simple model to explain such dependence is proposed. The model considers the mouth-throat system as a perfect mixing tank with a finite amount of odorants being progressively diluted by swallowing and purging (both taken as continuous processes). Retronasal intensity is modeled from the odor properties of the liquid in such a tank calculated from orthonasal odor intensity versus concentration (I/log C) curves. The model explains successfully experimental results and has also been successfully applied to instrumental data from other authors.

Performance on an odor detection and identification test as a predictor of ortho- and retronasal odor intensity ratings in the young and elderly

Two experiments were conducted to examine whether performance on the European Test of Olfactory Capabilities (ETOC, 16 odors to be detected and identified) can predict ortho- and retronasal odor intensity ratings. In Experiment 1 (Exp1), vanilla (0–0.31%) in a beverage (whey drink) was rated for ortho- and retronasal intensity and the ETOC was performed by elderly ( n = 27, 66–83, mean 74.4 years) and young ( n = 32, 22–36, mean 26.0 years). In Experiment 2 (Exp2), 17 elderly (67–84, mean 74.9 years) and 10 young (22–29, mean 25.9 years) performed the ETOC and rated varying concentrations of vanilla and lemon in aqueous solutions, grape juice and yogurt for ortho- and retronasal intensity. For the young, the mean detection/identification scores of the ETOC were 15.8/14.0 (Exp1), and 15.6/13.2 (Exp2). The corresponding scores for the elderly were 14.6/10.6 (Exp1) and 13.0/7.9 (Exp2). Orthonasally, the young differentiated the aroma concentrations in the whey drinks better than the elderly performing poorly in ETOC. Retronasally, the young and the well performing elderly gave higher intensity ratings for higher concentrations, while the poorly performing elderly were unable to do this. A tendency for small intensity difference in the poorly performing elderly was observed in ortho- and retronasal ratings for aqueous solutions, and orthonasal ratings for grape juice and yogurt. Retronasal intensity ratings of the elderly for grape juice and yogurt were not associated with their ETOC performance. Hence, olfactory performance measured by the ETOC predicted orthonasal intensity ratings, though not evidently, while its predictive ability for the retronasal intensity ratings of the elderly for complex food systems was deficient.

TIME‐INTENSITY MEASUREMENT OF MATRIX EFFECTS ON RETRONASAL AROMA PERCEPTION

ABSTRACTA computerized time intensity procedure was used to evaluate the retronasal aroma intensity of vanillin and limonene in oil/water emulsion. The maximum perceived retronasal intensity of limonene was decreased as oil content in the emulsion increased, but temporal perception (time to maximum intensity and total duration of perception) was not affected. Total duration of vanillin retronasal aroma increased as oil content increased, and salivary flow rate had a significant effect on perception of vanillin aroma. These results suggest that time intensity measurements may be a valuable tool for evaluating the effects of matrix interactions on retronasal aroma intensity.

Temporal patterns of nasal, oral, and retronasal perception of citral and vanillin and interaction of these odourants with selected tastants

SummaryPerceived intensities of aqueous solutions of 0.01% citral (C) and of 0.14% vanillin were estimated over time when presented nasally (sniffing), retronasally (sipping) and orally (sipping with nose pinched). the onset and decay of nasal perception was very rapid, with maximum intensity reached between 4‐8s and extinction between 9‐15s. the oral response was extremely low, while retronasal intensity reached maximum 11‐19 s after stimulation with a duration ranging from 40 to 120s. Orally, 10 of 19 subjects rated solutions containing C and citric acid (CA) significantly higher than those containing CA alone. Retronasally, citral intensity was enhanced by CA &gt; CA + sucrose (SUC) &gt; SUC &gt; NaCl. Addition of xanthan gum had little effect on perception of citral. Retronasal intensity of vanillin solutions was increased by addition of sucrose (SUC) and depressed by CA and by NaCl. the results demonstrated large differences in perceived intensity and duration via the three procedures, significant alteration of oral intensity by added tastants, and marked bimodality of response upon the addition of acid to citral.