Key food odorant profile for a narrowly tuned odorant receptor

Abstract

The recognition of key food odorants (KFO) appears to be the most eminent capability of odorant receptors (OR). However, the molecular mechanisms underlying a most sensitive detection of KFO are still largely unknown. Among the ~ 230 KFO, which appear above their odor threshold in foods, thiols engage an outstanding position, because of their extremely low odor thresholds. 3-mercapto-2-methylpentan-1-ol (MMP) is a KFO of the genus Allium with an odour threshold in the pg/L range. Most odorants activate combinations of OR that may be narrowly or broadly tuned. Consequently, a specific receptor activation pattern will define an odor quality. Receptor-activity patterns may be used in an objectified decision device for quality control or for food authentication purposes. In contrast, here we found a highly specific response of just OR2M3 out of ~ 400 human OR, to just 1 out of 190 KFOs and thiols tested, so far. This specific activation of extremely narrowly tuned human OR2M3 by a single onion key aroma compound suggests a human-specific, food-related function of OR2M3. This unique function suggests OR2M3 as an analytical biosensor for the sensitive detection of MMP as a quality control marker in different food matrices.