Olfactory Perception of 6 Amino Acids by Human Subject

• The olfactory properties of 6 amino acids were assessed in 20 human subjects using psychophysical tests of detectability,discriminability, and chemesthesis. Mean olfactory detection thresholds were found to be 10 lM for D-methionine, 80 lM forL-methionine, 200 lM for L-cysteine, 220 lM for D-cysteine, 75 mM for D-proline, and 100 mM for L-proline. When presentedat clearly detectable and intensity-matched concentrations, the subjects readily discriminated between the odors of the L-formsof cysteine, methionine, and proline, whereas they failed to distinguish between the L- and D-forms of a given amino acid. Thesubjects also failed in localizing the side of monorhinal stimulation with all 6 amino acids when presented at the sameconcentrations as in the discrimination tasks. These results suggest that amino acids may contribute to the flavor of food notonly as taste stimuli but also as olfactory stimuli perceived via ortho- or retronasal smelling. In contrast, it is unlikely that aminoacids contribute to flavor perception via chemesthesis. Given that the odors of 4 of the 6 amino acids tested here weredetected at concentrations lower than their corresponding taste detection thresholds, this may have important implications forthe widespread use of amino acids as food additives as well as for the evaluation of off-flavors caused by amino acids.

Nyckelord

amino acids

chemesthesis

olfactory discriminability

olfactory detection thresholds

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