Of the aroma chemicals that make up peppermint oil, the one most closely associated in the mind with the peppermint impression is menthol. Thus, it is surprising to realize that menthone is as essential as menthol or any other of the materials found in that oil. This conclusion is based upon the recent development of a new mint oil—Mentha spicata Eromenthe, which contains only menthone and its analogues and almost no menthol, menthyl esters or menthofuran. The analysis of this new mint is presented in Table I.
Menthone, minty peppermint with a high impact, imparts lift to flavors and fragrances in low or trace amounts. Nature suggests its use at low concentration by its presence at such levels in geranium or rose oil. When used in concentrations over 1% in a formula, menthone’s presence makes itself known by a shift to a peppermint impression, thus preventing its use in large amounts in anything but herbal-spice flavors with mint overtones.
Menthone is not widely distributed in the plant kingdom and is found in high concentrations in only a few species of plants with the species Mentha predominating. Menthone appears to arise from neryl pyrophosphate via the biosynthetic route shown in Figure 1. When used in flavor or fragrance compounds at low or trace concentrations, menthone or isomenthone often will not stand out; yet, trace amounts (a spike of methone) can lead unique effects to a composition.