Fault
Smoke taint
Ashtray, burnt and medicinal character in cider made from fruit exposed to wildfire smoke, which enters the fruit as bound precursors and is released later.
Also called smoke damage, bushfire taint.
- Severity
- Serious — the batch may not be salvageable
- Where it starts
- Orchard, Fruit preparation, Blending
- Can it be fixed?
- Yes, if caught in time
- When you notice it
- Orchard, Harvest
- Signs
- 5 recorded
What it is
Smoke taint is contamination of fruit by volatile phenols from vegetation smoke, most often from wildfire. The compounds are absorbed through the skin of the fruit and are largely bound to sugars within it, so smoke-affected fruit may smell almost normal. The bound forms are released during fermentation and, importantly, in the mouth, producing ashtray, burnt, medicinal and acrid characters that are worse on the finish than in the glass. It has become an increasingly serious question for orchards in fire-prone regions.
What you notice
Grouped by sense, because that is how the fault presents itself rather than how it works.
On the nose
- An ashtray or cold-fireplace character
On the palate
- A burnt, acrid or medicinal note in the finish — The retronasal, after-swallowing emphasis is characteristic, because bound precursors are released by enzymes in saliva.
In the mouth
- A drying, harsh aftertaste out of proportion to the cider’s tannin
How the batch behaves
- Fruit from a season in which smoke sat over the orchard
- Character intensifying during fermentation and over time in bottle — Hydrolysis of the bound forms continues, so a marginal cider can become clearly tainted later.
The words for it: Acrid smoke. Each links to what produces it.
When it appears. Set in the orchard where fruit was exposed to smoke, and carried through everything afterwards. It cannot arrive later.
The characteristic feature is that it can be masked in the aroma and then reappear on the palate and in the finish, because a substantial fraction of the responsible compounds are bound as glycosides and are released in the mouth. A cider that smells clean and finishes ashy is the signature.
Various journals
What it is mistaken for, and how to tell
One observation per rival, chosen because it separates them rather than because it describes either. Several of these are not faults at all — a style feature, a normal outcome, or the fruit behaving as it does.
- Brett character — Brett brings smoky together with leather, barnyard and sticking plaster; smoke taint arrives alone and is ashy rather than animal.
- Char from a heavily toasted barrel — Whether the cider was in wood. Barrel char gives toast and vanilla with the smoke; a taint gives smoke and ash without them.
- Mould taint — Ashy and acrid rather than damp and musty.
What is actually happening
The chemistry or microbiology behind it. Understanding the mechanism is what makes the prevention make sense rather than being a list of rules.
Combustion of lignin in vegetation produces volatile phenols — guaiacol, cresols, syringol and their derivatives — which are absorbed through the cuticle of the fruit. Once inside, the fruit conjugates them with sugars, principally as glycosides, which are non-volatile and effectively odourless.
This binding is what makes the fault so difficult. Analysis of free volatile phenols in the fruit or juice underestimates the eventual taint, because most of the material is present in bound form. Laboratories testing for smoke taint measure the glycosides as well as the free compounds for exactly this reason.
Release occurs by two routes. Acid and enzymatic hydrolysis during fermentation and ageing liberates some of the bound phenols over time. The rest are liberated in the mouth, where salivary enzymes cleave the glycosides and free the volatile phenols retronasally — which is why smoke taint is characteristically worse after swallowing and why it lingers.
Cider fruit is not obviously less susceptible than grapes, and the general mechanism is established across fruit crops. The published research base is overwhelmingly in wine grapes, so specific thresholds and cultivar susceptibilities for cider apples and perry pears should be treated as not yet established rather than assumed by analogy.
How it happens
| Cause | Stage | How often |
|---|---|---|
| Wildfire smoke over the orchard during the growing seasonSusceptibility is greatest in the period between veraison-equivalent ripening and harvest. | Orchard | occasional |
| Blending affected juice into a sound batch before the taint was recognised | Blending | occasional |
| Prolonged exposure to smoke from agricultural or forestry burning nearby | Orchard | rare |
| Fruit stored in a shed or building where smoke has accumulated | Fruit preparation | rare |
Can it be put right?
Most cider faults cannot be reversed. Where that is the answer it is given plainly — an honest 'this batch is what it is' is more useful than a procedure that will not work.
| Option | Effectiveness | What it involves |
|---|---|---|
| Do not press affected fruit | Reliable | The only reliable answer, and the reason testing before pressing matters. Once the fruit is in the vessel the decision has been made. |
| Fine with activated carbon or a selective adsorbent | Unlikely to work | Used in the wine industry with limited and inconsistent success, and it strips a great deal of the drink along with the taint. Not a home procedure. |
| Blend affected cider into a much larger sound volume | Unlikely to work | Sometimes helps at the margin, and risks tainting the sound cider as the bound precursors in the affected fraction continue to release. |
| Remove the taint from finished cider | Not possible | Bound precursors continue to release over time, so even a treatment that removed the free compounds would not stop the cider becoming tainted again. |
CiderHQ gives no additive dosage figures. An addition is a food-safety decision that depends on legal limits, on the juice in front of you and on what you are protecting against, and the right figure comes from your supplier’s or regulator’s own guidance rather than from a general reference.
Preventing it
- Where smoke has been over an orchard, test fruit for both free and bound volatile phenols before committing it to a batch.
- Keep fruit from a smoke-affected block separate through pressing and fermentation rather than blending it in.
- Make a small trial ferment from suspect fruit and taste it before deciding what to do with the crop.
- Wash fruit, which removes some surface deposition though not what has been absorbed.
- Recognise that a sensory assessment of the fruit or juice will underestimate the eventual taint, because most of the material is bound.
Smoke taint is included in a cider faults file because the geography of cidermaking now includes regions where wildfire is a recurring seasonal risk — parts of the western United States, Australia and elsewhere — and because a maker meeting it for the first time is likely to misdiagnose it as something else.
The bound-precursor mechanism is the part that catches people out. Fruit that smells almost normal can produce a cider that is clearly tainted, and a cider that seems marginal at bottling can be plainly faulty a year later, because hydrolysis of the glycosides continues throughout. Assessment by smell alone is not adequate.
The retronasal emphasis gives it a family resemblance to mousiness, and for the same underlying reason: the offending compounds are released in the mouth rather than being volatile in the glass. Both faults reward tasting by swallowing and waiting rather than by sniffing.
CiderHQ states the evidence position honestly. The mechanism is well established, and it has been established almost entirely in wine grapes. What has not been established for apples and pears specifically is which cultivars are most susceptible, what exposure produces what concentration, and what threshold matters in a cider matrix. A producer facing the question should be talking to a laboratory rather than to a rule of thumb.
Where in the process it arises
Fruit washing
Removing soil, grass, stones and surface contamination from gathered fruit, usually in a water flume, before it reaches the mill.
Fruit sorting
Taking rotten, mouldy and damaged fruit and foreign material out of the crop before it reaches the mill, which is the primary control on patulin in cider.
Climate and site risk
The weather exposures an orchard carries across its life — frost at bloom, summer drought, hail, wind and winter cold — and how a shifting climate is changing the balance between them.
Blending
Combining separate lots of cider or perry into one, which in cider is the historically normal way of making the drink rather than a remedy applied when single lots disappoint.
Ripeness assessment
Judging when cider fruit has converted enough starch, loosened enough on the spur and hardened enough for the store to be worth gathering.
Faults it is confused with
These present similarly. What separates them is set out on each page.
Brettanomyces character
Farmyard, horse-blanket, smoky and sticking-plaster aromas from *Brettanomyces* yeast converting hydroxycinnamic acids into volatile phenols.
Mould taint
Musty, earthy, cellar-damp or rotten-fruit character carried in from mouldy fruit or from mouldy equipment, and a marker that the patulin question needs asking.
Excessive astringency
A drying, roughening, mouth-puckering sensation that outstays its welcome, produced by larger phenolic polymers precipitating salivary proteins.
Where this comes up in a guide
The link lands on the step where the fault arises rather than at the top of the pathway, because that is where the decision that causes it is taken.
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 do you blend cider
- When are cider apples harvested — In the northern hemisphere the cider harvest runs from about September to November, with late bittersweets such as Dabinett and Vilberie coming in last. Cider fruit is generally picked riper than dessert fruit, and often gathered from the ground.
- Is brett a fault in cider — It depends on the tradition and the level. A trace of *Brettanomyces* character is expected in much West Country and Spanish cider; at high concentration it flattens fruit and dominates everything else, and few would defend it then.
- Why does my cider dry my mouth out — Astringency is tannin binding the proteins in saliva, which is felt as roughness rather than tasted. Too much comes from heavy pressing, long maceration, or fruit far higher in tannin than the blend can carry.
- What is mould taint in cider
- Are apples washed before making cider
Where to go next
- The fault finder — Describe what you can smell and see, and narrow it down from the signs.
- All faults — Grouped by where they come from and how serious they are.
- Cider science — The chemistry and microbiology these faults come out of.
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.
Washington State University cider research programme
Washington State University Northwestern Washington Research and Extension Center · university · passage verified 2026-08-24
The single most useful open cider dataset CiderHQ has found. The programme’s cultivar performance database gives juice chemistry, orchard behaviour, bloom and harvest timing and cider-maker tasting notes for 73 cultivars grown at one maritime site over fifteen years, and — unusually — publishes its classification thresholds alongside its figures, so the classification can be checked rather than taken on trust. It also states outright that its results diverge from the English ones. Read in full on 2026-08-24 and transcribed into `data/trials/wsu-mount-vernon.ts`; four published figures were found to be impossible and are withheld there with their reasons.
Peer-reviewed literature on apple phenolics and cider sensory perception
Various journals · peer-reviewed literature · registered as competent for this subject
Registered as a class rather than as one paper, because the mechanisms CiderHQ describes — tannin chain length driving the split between bitterness and astringency, salivary protein precipitation, enzymatic browning — are established across many studies rather than resting on any single one. Individual papers are cited where a specific number is quoted.
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.