Human Oral Sensitivity to and Taste Modulation by 3-Mercapto-2-Methylpentan-1-ol

Introduction

3-Mercapto-2-methylpentan-1-ol (3 M) is a key onion flavor (aroma), but past sensory work has focused primarily on ortho-nasal presentation. A series of experiments was conducted to characterize human sensitivity to oral 3 M solutions, then determine how 3 M impacts perception of basic tastes.

Methods

Detection thresholds were measured for a food grade, racemic mixture using a forced-choice staircase procedure (n = 19). Recognition was measured by presenting a single stimulus per trial (3 M, vanillin, or water), with "onion," "vanilla," or "water" as responses (n = 18). Supra-threshold intensity (n = 20) was measured for various concentrations using the general labeled magnitude scale (gLMS). Odor-taste interactions were studied using mixtures of 3 M and exemplars of basic tastes. Participants rated the intensity of basic tastes, or both taste and aroma, using the gLMS (n ranged from 10 to 15). All stimuli were in aqueous solution.

Results

Participants detected oral 3 M at about 0.90 ppb and recognized 3 M as "onion" at about 5 ppb. Supra-threshold intensity increased roughly as a cumulative logistic function of concentration. 3 M enhanced the rated savory intensity of monosodium glutamate, but did not enhance the dominant qualities of exemplars of the other four basic tastes. Under a response-context more favorable to an analytic approach, savory enhancement was reduced but not eliminated. Savory enhancement was eliminated with nose-clips.

Conclusions

Oral sensitivity was lower than previous retronasal studies would suggest, but roughly consistent with concentrations in cooked allium varieties. Oral 3 M selectively enhanced savory intensity, an effect likely due to retronasal aroma rather than taste or mouthfeel.

Implication

3 M is a promising candidate aroma to enhance or impart a savory flavor.

Smell and Taste Disturbance in COVID-19 Patients: A Prospective Multicenteric Review

To study the incidence of the smell and taste disturbance in the COVID-19 patients and a follow up at 4 months to observe for the duration of resolution of these symptoms. This is a multicentric prospective study carried out in 3 different countries, from April, 2020 to January, 2021. The COVID-19 positive patients, aged between 15 and 60 years, were inquired about the presence of any smell or taste related symptoms. The same patients were followed up with the telephonic interview after 2 months and then after 4 months, respectively. The duration of resolution of the smell and taste disturbance symptoms was noted. Total of 188 COVID-19 positive patients, average age 33.1 ± 1.7 years, 54.2% males and 45.8% female were included in the study. The smell disturbance was present in 60.6% (hyposmia 36.1%, anosmia 20.2%, and parosmia 4.2%) and taste disturbance in 28.7% of patients (hypogeusia 20.2%, ageusia 6.9%, and parageusia 1.6%). There was improvement of anosmia by 97.4, hyposmia by 95.6%, parosmia by 100%, ageusia by 100%, hypogeusia 94.8%, and parageusia by 66.7%, at 4 months follow up. The present study concludes that the smell and taste disturbances are one of the main early presenting features of the COVID-19 infection. The temporary effect of the COVID-19 infection on the olfactory and gustatory pathway was also highlighted with more than 95% patients improving at 4 months of follow up.