Eugenol
Also written eugenol (clove oil), 4-allyl-2-methoxyphenol
Quick answer
The smell of cloves, and the compound that carries a genuine local anaesthetic effect — the reason a clove held against a sore tooth is a practice found in a dozen unconnected traditions.
What it does
Eugenol is the sweet, medicinal, faintly bitter smell of cloves, and it is unusually dominant: clove oil is largely eugenol, which is why cloves are among the hardest spices to use subtly and why a single clove too many is instantly recognisable. It produces a distinct numbing sensation on the tongue and gums at concentration, separate from its aroma. In allspice it sits alongside enough other aromatics to read as one note in a compound smell rather than as the whole of it, which is precisely why allspice is often described as a blend of cloves, cinnamon and nutmeg and is in fact a single berry.
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
Eugenol is more heat-stable than most aroma compounds and it is stubbornly fat-soluble, and both facts show up in how cloves are used everywhere they are used. It survives long braising, roasting and baking with its character intact, which is why cloves are a fixture in dishes cooked for hours — hams, stocks, biryani, mulled wine — and why the traditional applications almost all involve extended cooking rather than a finishing touch. Its poor water solubility means that a clove simmered in a watery liquid gives up its aroma slowly and incompletely; in a fatty stock or in wine it extracts readily. The practical consequence cooks discover the hard way is that eugenol accumulates rather than dissipates: a long-cooked dish gets more clove-forward with time, not less, so cloves are counted into a braise at the start and removed, not added freely.
Spices that carry it
Recorded on the compound rather than on each spice, so the two cannot disagree.
- AllspicePrincipal component
The reason allspice reads as clove-adjacent. It is a genuine chemical relationship rather than a coincidence of description.
- ClovesPrincipal component
- Cinnamon (Ceylon)Major component
Present in true cinnamon and essentially absent from cassia. This is the single biggest chemical difference between the two barks and the one a taster notices.
- BasilContributing component
Varies enormously by cultivar. Holy basil and several Asian basils are markedly eugenol-forward, which is why they read as clove-like and why they are not interchangeable with sweet basil.
- Bay leafContributing component
- Hoja santaContributing component
Not to be confused with
Compounds a reader is likely to take for this one, and why they differ.
Safrole
Structurally close relatives, and their regulatory treatment could not be more different: eugenol has an established acceptable intake as a flavouring, and safrole is prohibited outright as a food ingredient in the United States.
Regulatory position
Held on the compound, because the restriction is a fact about the molecule rather than about any one spice.
International (Codex/JECFA)
permittedJECFA evaluation of eugenol and related hydroxyallylbenzene derivatives
Eugenol has been evaluated as a flavouring substance and carries an acceptable daily intake. This is a statement about eugenol added as an isolated flavouring, not a limit on cloves, and the figure itself must be read from the monograph rather than quoted second-hand.
Safety
What the concern is. The dose, the population and the evidence level live on the spice profiles, which is where a reader with that question actually arrives.
The exposure that carries documented concern is clove oil rather than cloves: the concentrated oil has been associated with liver injury in overdose, particularly in children, and it is an oral mucosal irritant. Whole and ground cloves used as a seasoning are not the same exposure and no competent source in this library treats them as one.
Questions this page answers
- what is eugenol
- what does eugenol do
- which spices contain eugenol
- what is 4-allyl-2-methoxyphenol