An Aroma Chemical Profile: Menthol

L-menthol can be described as unique for its cooling sensation on the skin and mucous membranes. Although other materials are known to display this cooling effect, almost all of them are derivatives of l-menthol.

L-menthol displays a minty, light, refreshing odor that at most practical concentrations is complicated by the intense cooling sensation. This dual sensory effect makes the odor evaluation of menthol a difficult task. At very low concentrations, menthol displays a slight warming sensation along with the refreshing mint odor. At moderate concentrations, the cooling effect develops, which, as concentration increases, becomes overwhelming and produces an anesthetic reaction. This numbing effect creates the soothing of the throat desired in cough drops. The overwhelming effect can best be illustrated by walking into a menthol production facility. One literally walks into a wall of menthol which registers in the eyes, nose and mouth first and as the vapor permeates one’s garments, the whole body tingles.

The cooling-anesthetic effect interferes greatly in the odor evaluation of menthol for trace impurities, which can be critical in applications where menthoI is used by itself and at low concentrations, i.e. tobacco products. The impurities are less critical where menthol is combined with other materials such as anethol, methyl salicylate or carvone, i.e. oral hygiene products. However, there are cases where even in such products the trace impurities stand out.

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