UC San Diego

Chemosensory detection of airborne chemicals by humans is accomplished principally through olfaction and mucosal chemesthesis. Odors are perceived via stimulation of the olfactory nerve (CN I) whereas nasal chemesthetic sensations (i.e., prickling, irritation, stinging, burning, freshness, piquancy, etc), grouped under the term nasal pungency, are mediated by the trigeminal nerve (CN V). Airborne compounds elicit odor sensations at concentrations orders of magnitude below those producing pungency but the physicochemical basis for odor and pungency potency of chemicals, either singly or in mixtures, is far from being understood. The sensitivity of the sense of smell often outperforms that of the most sophisticated chemicoanalytical methods like gas chromatography and mass spectrometry. Still, the combined used of these techniques with human odor detection (i.e., olfactometry) has proved an invaluable tool to understand the chemosensory properties of complex mixtures such as foods, flavors, and fragrances.