Thymol
Also written thymol (phenol)
Quick answer
The sharp, medicinal phenol of thyme, oregano and ajwain — and, with its isomer carvacrol, the compound that decides which of those a herb tastes like.
What it does
Thymol is penetrating, medicinal and slightly sweet, with a bitterness on the tongue and a mild burn at concentration. It is the smell of a traditional antiseptic mouthwash, which is not a coincidence — thymol was used for exactly that. Where it dominates, as in thyme and ajwain, the herb reads as clean, sharp and clinical; ajwain in particular is so thymol-forward that it is often described as a concentrated thyme, which is chemically apt even though the plants are unrelated.
How it behaves when cooked
Four properties of the molecule, and what they mean at the stove.
- Volatility
- moderate
- Fat solubility
- high
- Water solubility
- low
- Heat stability
- high
Thymol is a phenol rather than a simple terpene, and it behaves accordingly: heavier, less volatile and considerably more heat-stable than the aromatics around it. That is why thyme is one of the few soft herbs that survives long cooking and belongs in a stock, a braise and a bouquet garni, while its lighter companions do not — and why dried thyme is a genuinely useful ingredient where dried basil is not. Its poor water solubility and strong fat solubility mean thyme gives far more to an oil, a roast or a fatty stew than to a watery one. In ajwain, the same stability is why the seed is bloomed in hot fat at the start of a dish rather than added at the end: the treatment develops it rather than destroying it.
Spices that carry it
Recorded on the compound rather than on each spice, so the two cannot disagree.
- AjwainPrincipal component
Exceptionally thymol-dominant, which is why a small quantity reads as overwhelming and why ajwain is measured by the pinch in dishes where thyme would be measured by the spoon.
- ThymePrincipal component
- Za'atar herbPrincipal component
- OreganoMajor component
- SavoryMajor component
- MarjoramContributing component
- Mexican oreganoContributing component
An unrelated plant in the verbena family that carries the same phenols, which is the entire reason it is called oregano and the entire reason the substitution partly works.
Not to be confused with
Compounds a reader is likely to take for this one, and why they differ.
Carvacrol
Isomers with the same formula, differing in where one group sits on the ring. Thymol reads as thyme and carvacrol reads as oregano, and the ratio between them is the single best chemical predictor of which a given leaf will taste like — including within a species, where cultivar and growing conditions shift the balance.
Questions this page answers
- what is thymol
- what does thymol do
- which spices contain thymol