Sensory descriptor
Bacon
A savoury smoked-meat note from 4-ethylguaiacol with residual sweetness, met in tannic ciders with Brett character.
Also called Smoked meat, Ham.
- Aroma family
- Phenolic
- Does it indicate a fault?
- It depends on the style it is met in
What causes it
4-ethylguaiacol carries a smoked-meat as well as a wood-smoke character, and which of the two a taster perceives depends on what accompanies it. Where residual sugar or glycerol supplies a rounder base and the drink carries some savoury depth from lees ageing, the perception is bacon; in a bone-dry cider the same compound reads as bonfire. Low levels of biogenic amines and of the amino-acid degradation products of long lees contact reinforce the savoury reading.
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-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.
Glycerol
A syrupy three-carbon alcohol yeast produces as a side reaction of fermentation, which adds weight to a dry cider and is the raw material for one of its more obscure faults.
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.
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.
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.
Back-sweetening
Adding sugar, juice or concentrate to a cider that has fermented dry — a straightforward adjustment that leaves the drink microbiologically unstable until something is done about it.
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 Bacon
Bacon is a narrow descriptor and is included because it names a recognisable variant of the smoky perception that panels otherwise dispute. It reports on what the volatile phenol is sitting in rather than on a different compound.
It should be recorded alongside the rest of the phenolic cluster rather than alone; a cider showing bacon and nothing else in the family is unlikely to have been correctly identified.
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.
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.
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 make my cider sweeter
- 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.
- What does glycerol do in cider — Glycerol is a by-product of fermentation that is faintly sweet and viscous, and it contributes to the impression of body and roundness in a dry cider.
- What is a traditional west country cider blend — Predominantly bittersweet fruit for body and tannin, with a proportion of sharp fruit for acidity and sometimes a smaller share of bittersharps for both. The exact composition varied by farm and by what was in the orchard.
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.
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.
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.