Compound
Eugenol
The clove compound of oak and of actual cloves, arriving in cider from wood contact or from deliberate spicing rather than from the fruit.
Also called Clove oil.
- Class
- Phenolics
- Formula
- C10H12O2
- How often it matters
- Specialist — met in particular circumstances
What it does in cider
- Enters cider from oak, where it is released from the wood’s lignin, and from added spice in a spiced cider.
- Contributes a warm clove and allspice note that reinforces the vanilla and coconut of oak contact.
- Increases with barrel toasting up to a point and declines with heavy toasting, since the compound is itself degraded by heat.
- Diminishes with successive fills, because a barrel’s extractable compounds are finite.
How it is perceived
What the compound registers as, and at roughly what concentration. Perception is not a property of the molecule alone: sugar, tannin and carbonation all change where a threshold falls.
- clove
- allspice
- warm spice
- medicinal at high level
A potent aroma compound perceptible at low concentration, which is why a light touch of oak reads as spice before it reads as wood.
Descriptors it is responsible for
Sensory records that name Eugenol as a cause. Each states the perception and the mechanism behind it.
- Oak — Direct wood character from barrel contact: tannin, lactones and phenolic aldehydes extracted from the staves.
- Apple pie — Cooked apple carrying a spice layer — clove, cinnamon or nutmeg — from added spice, from wood, or from yeast-derived vinylguaiacol.
- Cinnamon — Warm sweet-spice character from cinnamaldehyde in added spice, or from oak-derived compounds in a barrel-aged cider.
- Mulled spice — The combined clove, cinnamon and citrus-peel character of a mulling blend, always an addition.
- Nutmeg — A dry, woody-sweet spice note from added nutmeg or mace, or from oak-derived phenylpropanoids.
The structure it moves
| Dimension | What it is |
|---|---|
| Phenolic character | Smoky, spicy, leathery or medicinal aromas that sit apart from fruit. |
| Fermentation character | Aromas made by the ferment rather than carried in from the fruit. |
What forms it
Processes that put this compound into the drink, or increase how much of it is there.
Barrel ageing
Holding cider in wood — which may mean an old neutral vat used simply as a vessel, or fresh or spirit-seasoned oak used as a source of flavour, and the two are not the same operation.
Wood and botanical infusion
Steeping oak in chip, cube or stave form, or bark, root, herb and flower material, in a neutral vessel to flavour a cider without the vessel itself doing any of the work.
Spicing
Extracting aromatic compounds from spice into cider, either cold as a production step or hot in the old mulling tradition, with clove, cinnamon-type barks and citrus peel doing most of the work.
About Eugenol
Eugenol is the principal aroma compound of clove, and it is also one of the compounds oak gives up to anything stored in it. In a barrel-aged cider it arrives with the vanillin and the oak lactones as part of the wood signature, and it is largely responsible for the impression that a wooded cider has been spiced when nothing has been added to it.
How much a barrel delivers depends on the toasting. Heating the staves breaks down lignin and releases eugenol along with vanillin and the guaiacols, but heavy toasting degrades what light toasting released, so the relationship between char level and clove character is not linear.
In a spiced cider it arrives directly, and the practical point is that the same molecule reaches the drinker by two routes. A cider carrying oak-derived eugenol and one carrying clove-derived eugenol can smell similar, and telling them apart depends on what else came with it — vanillin and lactones from a barrel, or the terpenes and other spice volatiles from an addition.
Related compounds
Compounds it is formed from, converted into, confused with, or routinely met alongside.
Aldehydes
Vanillin
The vanilla compound released from oak lignin, and a good illustration of why fermenting in a barrel gives less wood character than maturing in one.
Esters
Oak lactones
The coconut-and-wood compounds of oak, whose concentration depends more on which species of oak the barrel was made from than on anything a cidermaker does.
Aldehydes
Furfural
A toast-and-almond aldehyde formed whenever sugars are heated, arriving in cider either from a toasted barrel or from heat treatment, and a reliable marker of cooked character.
Phenolics
4-Vinylguaiacol
The clove compound produced by any yeast carrying a ferulic acid decarboxylase, which gives a spicy character without any Brettanomyces being involved.
Phenolics
Terpenes
The floral and citrus aroma compounds that apples carry only in traces and that hops, spices and botanicals bring in quantity, which is why a hopped cider smells so different from an unhopped one.
What people ask next
Questions readers ask about the things this page mentions. Each one goes to the section that answers it rather than to a page written to receive the question.
- Should i ferment cider in an oak barrel — A sound, full barrel is a fine maturation vessel; a leaky, half-empty or previously spoiled one is the fastest route to vinegar. Wood cannot be sterilised, so a barrel carries whatever lived in it before.
- Where does vanilla flavour in cider come from
- How do you spice a cider
- Are there terpenes in cider
- What are oak lactones
- What is furfural
Where to go next
- All compounds — Grouped by what the fruit brings and what the ferment makes of it.
- Sensory — Every descriptor, with the compound or process that causes it.
- Microbiology — The organisms whose metabolism most of this chemistry belongs to.
Sources
What this page rests on. Where a source is marked as registered rather than read, CiderHQ is recording that the body is authoritative on the subject without claiming to have worked through the document itself. See our evidence policy for what each state means.
The Science of Cidermaking and associated technical writing
Andrew Lea · reference work · passage verified 2026-08-24
Written by a food chemist who worked at Long Ashton on apple phenolics. Unusual among specialist cider writing in that it is primary-research-adjacent: the author is describing work he did, and cites the literature. This is why it is registered at tier 1 for chemistry while a general cider book is not.
Cider and perry production technical training material
Peter Mitchell / Cider and Perry Academy · reference work · registered as competent for this subject
Searched again on 2026-08-25 and it remains the one printed source here that a bibliographic check cannot fix, because it is not a published work with an edition. It is course material issued to participants of a training programme, so there is no catalogue record to verify, no ISBN, and no lawful public copy. Its state stays `registered` for that reason rather than through inattention.