Friday, April 8, 2011

WHAT IS MENTHOL?


Chemically, menthol is a monocyclic terpene alcohol. It is a naturally occurring chemical chiefly derived from the peppermint plant (Mentha piperita) or the corn mint (Mentha arvensis), but it can also be synthetically produced. The chemical structure of menthol is shown in Figure 1. Menthol can exist as
one of eight stereoisomers—molecules with identical formulas but different three‐dimensional shapes.

These isomers include menthol, isomenthol, neomenthol and neoisomenthol, each of which can exist asl, also called (‐), or d, also called (+). Each of the tereoisomers has distinct pharmacologic characteristics. The l, or (‐), isomer of menthol is the natural isomer and conveys the typical taste and sensory characteristics of menthol. The d, or (+), isomer is active but less so than l‐menthol
.
Tobacco companies use both natural and synthetic menthol in cigarettes. The natural menthol found in cigarettes (l isomer) is typically crystallized from steam‐distilled oil of the corn mint plant. Synthetic menthol (dl ‐ menthol) is racemic, meaning it contains both the d and l isomers and has different taste characteristics from natural menthol. Some cigarette manufacturers use natural menthol only; others use a mixture of natural and synthetic menthol. Natural menthol has been reported to impart greater cooling and mintness and less sharpness, perhaps due to trace chemicals in the natural extract.

Menthol is added to cigarettes in numerous ways:
(1) spraying the cut tobacco during blending;
(2)application to the pack foil;
(3) injection into the tobacco stream in the cigarette maker;
(4) injection into the filter on the filter maker;
(5) insertion of crushable capsule in the filter;
(6) placement of a menthol thread in the filter;
(7) a combination of the above (

Over time, menthol diffuses throughout the cigarette irrespective of where it was applied. Menthol cigarettes are typically blended using more flue‐cured and less burley tobacco. This is because some of the chemicals in burley tobaccos create an incompatible taste character with menthol.