Odorous and pungent attributes of mixed and unmixed odorants

Abstract

In order to explore functional properties of the olfactory and common chemical senses as well as their relation to the total nasal sensation experienced, various concentrations of two pungent odorants were presented alone and in the presence of different backgrounds of the other irritant. Stimuli comprised formaldehyde (at 1.0, 3.5, 6.9, and 16.7 ppm), ammonia (at 210, 776, 1,172, and 1,716 ppm), and their 16 possible binary mixtures. Subjects were asked to estimate the total nasal perceived intensity, and then to assess the olfactory (odor) and common chemical (pungency) attributes of the evoked sensations. The results showed that stimulus-response functions for pungency are steeper than those for odor. Furthermore, odor was always hypoadditive in mixtures (i.e., mixtures were perceived as less intense than the sum of their components), whereas pungency was, mainly, additive, and even suggested hyperadditivity. Total perceived intensity of the stimuli, alone and in mixtures, followed the stimulus-response patterns for pungency, which, therefore, emerged as the dominating attribute used by subjects in scaling the explored range of concentrations. The relationship between total nasal perceived intensity of the mixtures and that of their components reflected hypoaddition, resembling the outcome for the odor attribute.Humans are able to detect airborne chemicals in the environment by means of two sensory systems present in the nose: the olfactory sense and the common chemical sense (CCS). Common chemical sensitivity is not restricted to the nasal mucosa, but extends to the oral mucosa and the conjunctiva. So far as is known, the CCS lacks specialized receptors, which the other chemical sensestaste and smell-have, so the sensations aroused by CCS stimulation are mediated principally by free nerve endings of the trigeminal nerve (Beidler,

Dose-addition of individual odorants in the odor detection of binary mixtures

“…One general observation is that, irrespective of level, the trigeminal chemosensory system tends to integrate the impact of mixed stimuli in a more complete way than olfaction [16][17][18]. This leads to a higher degree of dose additivity in the irritation modality across the complete perceptual range.…”

Trigeminal Chemosensation

“…Some attempts to separate odor responses from nasal pungency (i.e., irritant) responses entailed instructing subjects to focus on one type of sensation and ignore the other (e.g., Cometto-Muñiz, García-Medina, and Calviño, 1989;Cometto-Muñiz and Hernández, 1990). This strategy has merit for the study of suprathreshold sensations and finds validation in the aforementioned Doty et al (1978) study, where the responses of anosmics and the trigeminal-focus group show overall good agreement.…”

Chemosensory Detectability of 1-Butanol and 2-Heptanone Singly and in Binary Mixtures

“…When the type and concentration of the mixed chemicals appeals not only to the olfactory but also to the nasal trigeminal system, the degree of additivity grows larger (18). A perceptual dissection of the overall chemosensory response into "odor" and "nasal pungency" revealed that the chemesthetic response, as opposed to the olfactory response, showed complete additivity and, even, hyperadditivty (19).…”