Sensory descriptor
Horse blanket
An animal, stable-like note from 4-ethylphenol combined with branched short-chain fatty acids.
Also called Horsey, Stable, Sweaty horse.
- Aroma family
- Phenolic
- Does it indicate a fault?
- It depends on the style it is met in
What causes it
Horse blanket is 4-ethylphenol with company. The volatile phenol supplies the medicinal core, and isovaleric acid — produced by yeast and by lactic bacteria from leucine catabolism, and by Brettanomyces in particular — supplies the sweaty, animal dimension that turns antiseptic into stable. Small quantities of 4-ethylguaiacol add a smoky edge. The perception depends on the ratio: high 4-ethylphenol with little isovaleric acid reads as sticking plaster, and the reverse reads as cheesy.
A low level is characteristic of traditional wood-matured cider and is what many drinkers mean when they call a cider funky. Above that the animal component becomes the dominant impression and the drink is judged faulty in every framework including those that tolerate the underlying phenols.
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.
4-Ethylguaiacol
The smoky, clove-like partner of 4-ethylphenol, made by the same organisms from ferulic acid, and the compound that pushes phenolic character from medicinal towards spicy.
Amino acids
The largest usable nitrogen fraction in apple juice, and the raw material from which yeast builds both its own protein and most of the aroma compounds a cider carries.
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.
Wild fermentation
Letting the microflora already present on the fruit and in the press house carry the ferment, in a succession rather than as a single organism.
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.
Lees ageing
Deliberately holding a cider or perry on its fine yeast deposit so that autolysing cells release material that changes texture and foam behaviour.
Sanitation
The cleaning and sanitising discipline that underlies every other process, and why removing soil must come before any attempt to kill organisms.
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 Horse blanket
Horse blanket and farmyard describe overlapping perceptions and are often used interchangeably. The distinction worth preserving is that farmyard is the broader composite including straw and earth, while horse blanket is specifically the animal component of it.
Because isovaleric acid is a bacterial as well as a yeast product, this note can develop in a cider with no Brettanomyces present at all, driven by lactic bacteria in a low-sulphite environment. Testing for 4-ethylphenol distinguishes the two.
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.
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.
Leather
A dry, tanned-hide note from low levels of volatile phenols over well-polymerised tannin.
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.
- How does cider ferment — Yeast consumes the sugar in apple juice and produces roughly equal masses of ethanol and carbon dioxide, along with the esters and higher alcohols that give cider much of its aroma. In a wild ferment several yeast species take turns before *Saccharomyces* finishes the job.
- How do i sterilise cider bottles — Wash them clean first, then sanitise with a no-rinse sanitiser or a sulphite solution, and fill while still wet with it. Bottles that look clean but have dried deposits inside are the usual source of bottle spoilage.
- 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.
- What is scrumpy — Scrumpy is an informal West Country word for strong, still, usually cloudy farmhouse cider. It has no legal definition, so it describes a style expectation rather than a guaranteed method.
- What is sidra natural — Sidra natural is the still, dry, unfiltered cider of Asturias and the Basque Country, bottled without added carbonation and poured from a height to rouse it. It is tart, funky and made to be drunk in small measures poured one at a time.
- 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 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.
Peer-reviewed literature on cider fermentation microbiology
Various journals · peer-reviewed literature · registered as competent for this subject
Covers the microbial succession of spontaneous cider fermentation, the role of non-Saccharomyces yeasts in the early stages, malolactic conversion by Oenococcus and Lactobacillus species, and the organisms behind the principal spoilage faults.
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.
Servicio Regional de Investigación y Desarrollo Agroalimentario (SERIDA)
Principado de Asturias · research institute · retrieved 2026-08-24
The Asturian regional agri-food research service, and the technical authority behind the Asturian cultivar classification and the analysis of sidra natural. SERIDA’s own site has not been opened; what CiderHQ has read is SERIDA’s varietal characterisation as republished by the Consejo Regulador of DOP Sidra de Asturias, which credits it explicitly. The Asturian measurements therefore cite the Consejo rather than SERIDA — citing the body that did the work, at a document CiderHQ has not seen, would be exactly the kind of borrowed authority this register exists to prevent.