Menthol, also known as mentha brain, scientific name Menthol, commonly known as menthol ice, natural left-handed CAS No. 2216-51-5, racemate CAS No. 89-78-1, is a naturally occurring cyclic monoterpene compound and also a core functional component of mint plant essential oil. It appears as colorless transparent needle-like or columnar crystals, has a strong characteristic mint aroma and cooling sensation, and is one of the raw materials with the largest global output and widest application in cooling products.

Menthol is mainly divided into two types: L-menthol (left-handed menthol) and DL-menthol (racemic menthol). The former is obtained through natural extraction or synthetic resolution, has a pure and strong cooling effect, and is the mainstream product in the market; the latter is an artificially synthesized racemate, has slightly weaker cooling intensity, lower cost, and is mostly used in industrial-grade scenarios.