Sensory descriptor
Leather
A dry, tanned-hide note from low levels of volatile phenols over well-polymerised tannin.
Also called Saddle, Tanned hide.
- Aroma family
- Phenolic
- Does it indicate a fault?
- It depends on the style it is met in
What causes it
Leather is the mildest and driest expression of volatile phenol character, and it requires a phenolic structure underneath it. Low concentrations of 4-ethylphenol and 4-ethylguaiacol, sitting over long-chain polymerised procyanidins in a tannic cider that has aged, produce it; the same phenols in a low-tannin cider read as medicinal instead, because there is nothing to give the perception its dry, tactile framing. It is therefore a note of mature bittersweet cider rather than of any cider with Brettanomyces in it.
The compounds responsible
Where the molecule is established. Some descriptors in this lexicon name a compound the compound register does not yet hold a record for; those are named in the cause above instead.
4-Ethylphenol
The horse-and-sticking-plaster compound, made by *Dekkera* from a phenolic acid the fruit supplied, and the clearest case in cider of one molecule being a tradition in one glass and a fault in another.
Procyanidins
The condensed tannins of cider fruit, whose chain length — not their quantity — decides whether the mouth registers bitterness or astringency.
Total phenolics
The single number used to summarise everything phenolic in a juice, useful for comparing fruit and misleading whenever it is used to predict how a cider will taste.
The organisms that make it
Where a specific organism is implicated rather than the fruit. Naming one answers a different question from naming a molecule: what is in the cellar, rather than what is in the glass.
What raises it
Processes that increase this character, or preserve it where it would otherwise be lost.
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.
Oxidative maturation
Ageing a cider with a deliberate, measured oxygen supply so that tannins polymerise and soften and an aldehydic character develops on purpose, which is not the same thing as the oxidation fault.
Bottle maturation
What happens to a cider after it is sealed in glass — which for most ciders is slow decline rather than improvement, and saying so is more useful than implying otherwise.
Tannin balancing
Setting the phenolic structure of a blend, which means handling bitterness and astringency separately because they are different perceptions produced by different sizes of the same molecules.
The fault it points at
Meeting this descriptor above a certain intensity is how the fault below is usually noticed first.
Fault
Farmyard, horse-blanket, smoky and sticking-plaster aromas from Brettanomyces yeast converting hydroxycinnamic acids into volatile phenols.
Where it is usually met
Fruit and styles this character is recorded in. A record here is where the descriptor is commonly found, not a claim that every example shows it.
About Leather
Leather is the descriptor most often used to name volatile phenols at a level a taster is content with, and it is worth using precisely for that reason: it records the same chemistry as sticking plaster at a different intensity and in different company.
It is closely associated with age. A young cider with the same phenol concentration and unpolymerised tannin reads as harsh and medicinal, and it is the softening of the tannin over a year or more that permits the leather perception at all.
Others in the phenolic family
Leather, smoke, sticking plaster, horse, medicinal.
Sticking plaster
The sharp antiseptic-and-adhesive note of 4-ethylphenol, the principal volatile phenol of *Brettanomyces* activity in cider.
Horse blanket
An animal, stable-like note from 4-ethylphenol combined with branched short-chain fatty acids.
Medicinal
A hospital-antiseptic note from volatile phenols, or from chlorophenols formed by chlorine contacting phenolic material.
Smoky
A wood-smoke note from 4-ethylguaiacol, the guaiacyl counterpart of the ethylphenol pathway.
Acrid smoke
Harsh, ashy smoke from atmospheric smoke absorbed by the fruit, chemically distinct from microbial smokiness.
Bacon
A savoury smoked-meat note from 4-ethylguaiacol with residual sweetness, met in tannic ciders with Brett character.
Plastic
A synthetic, hot-plastic or crayon note from packaging materials, hose or liner contact.
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.
- Does cider get better with age — Some does. Tannic, dry, bottle-conditioned ciders and ice ciders can gain for several years. Light, fruit-driven and commercially filtered ciders lose their aroma and do not gain anything in exchange.
- What are procyanidins in cider — They are the condensed tannins of apples: chains of catechin-type units whose length decides how much of the phenolic load reads as bitterness and how much as astringency. Two ciders with identical total tannin can taste nothing alike.
- What is brettanomyces — *Brettanomyces*, correctly *Dekkera* in its spore-forming form, is a slow yeast that ferments sugars other strains leave behind and produces volatile phenols smelling of farmyard, leather or sticking plaster. In cider it is common and not always unwanted.
- 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.
- Does cider contain antioxidants — Cider carries apple polyphenols, and tannic bittersweet ciders carry considerably more than pale ones made from dessert fruit. What that means for health is a clinical question this site does not adjudicate.
- What causes a farmyard or barnyard smell in cider — Usually 4-ethylphenol, made by Brettanomyces from hydroxycinnamic acids in the juice. Whether it is a fault depends on the cider: a trace adds complexity to a traditional cider and dominates a fresh fruit-forward one.
Where to go next
- The sensory model — The thirteen structural dimensions and the twenty aroma families, in full.
- Compounds — The chemistry behind the words.
- Troubleshooting — When a perception turns out to be a problem, this is where it is diagnosed.
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.
Institut national de recherche pour l’agriculture, l’alimentation et l’environnement (INRAE)
INRAE · research institute · retrieved 2026-08-24
French national agricultural research. Its Angers programme produced much of the published work on apple procyanidin chain length and on the relationship between polymer size, bitterness and astringency.
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.
A Somerset Pomona: The Cider Apples of Somerset
Liz Copas, The Dovecote Press, 2001. ISBN 9781874336877 · reference work · bibliographic record verified, not opened 2026-08-25
Bibliographic record verified on 2026-08-25 against Open Library: Liz Copas, The Dovecote Press, 2001, ISBN 9781874336877. The author was Long Ashton’s cider pomologist, which is why this work is registered for Somerset cultivar identity at all — it is the nearest thing to a successor to the station’s own descriptions. No copy was opened. Not digitised in any open collection.