Metabolism of Odorants in Humans

This chapter outlines the metabolism of important food odorants foododorant and its impact on their bioactivity. The first section describes general metabolic pathways including functionalization (phase 1), conjugation (phase 2) and export (phase 3). These pathways are intended to excrete the compounds, which can be regarded as xenobiotics. In the second section, the metabolism of important classes of odorants, that is, alcohols and aldehydes, esters, thiols, terpenes, and phenylpropanoids is presented in detail. Among the terpenes, the focus lies on the monocyclic monoterpene hydrocarbon carvone, the monocyclic monoterpene ketone pulegone, the bicyclic monoterpene oxide 1,8-cineole, the bicyclic monoterpene ketone thujone, and on the allylalkoxybenzenes estragole and methyleugenol and coumarin among the phenylpropanoids. Recent studies are presented and each pathway is depicted in a separate reaction scheme. The contribution of each path either to detoxification or to toxification is discussed. The last section finally deals with conclusions and an outlook for further research.