Menthol, scientifically known as menthol, is a naturally occurring cyclic monoterpene alcohol compound. Its levorotatory form has CAS number 2216-51-5, and its racemic form has CAS number 89-78-1. It is the core active ingredient in the volatile oil of peppermint plants. It appears as colorless, transparent needle-like or prismatic crystals, possessing a strong, characteristic minty aroma and a cooling sensation. It is one of the world's most produced and widely used cooling ingredients.
Commercially available menthol is mainly divided into two categories: **L-menthol (levorotatory menthol) and DL-menthol (racemic menthol).** The former is obtained through natural extraction or synthetic separation, and has a pure and strong cooling sensation, making it the mainstream product on the market. The latter is an artificially synthesized racemic mixture, which has a slightly weaker cooling intensity and lower cost, and is mostly used in industrial applications.