Fault
Cork taint
A damp-cardboard, wet-newspaper mustiness from trichloroanisole, usually carried by a natural cork but capable of reaching cider by other routes.
Also called corked, TCA taint.
- Severity
- Quality — the drink is worse for it
- Where it starts
- Packaging, Maturation, Storage
- Can it be fixed?
- Yes, if caught in time
- When you notice it
- Packaging, Storage
- Signs
- 5 recorded
What it is
Cork taint is the musty, damp-cardboard character caused principally by 2,4,6-trichloroanisole, a compound formed by moulds acting on chlorophenols. It reaches a bottle most often through a natural cork closure, which is why it carries that name, but the same compound can come from cellar timber, from pallets, from crates and from anywhere chlorine-based products have met wood. It suppresses aroma before it becomes obvious in itself, so a mildly tainted bottle often reads as dull rather than as faulty.
What you notice
Grouped by sense, because that is how the fault presents itself rather than how it works.
On the nose
- A wet cardboard, damp newspaper or mouldy-cellar smell
- A bottle that smells of almost nothing when it should be aromatic — Aroma suppression comes before the musty note is obvious, and a bottle that seems merely dull may be lightly tainted.
On the palate
- A dry, dusty impression on the finish
How the batch behaves
- One bottle from a case being wrong while the others are fine — Bottle-to-bottle variation is the signature of a closure-borne taint.
- The character intensifying as the cider warms in the glass
The words for it: Corked. Each links to what produces it.
When it appears. On opening, and only in the affected bottles. A taint that is present in every bottle did not come from the corks.
Individual sensitivity to the responsible haloanisoles varies by orders of magnitude, and some people cannot detect them at all at ordinary concentrations. This is the clearest case on the site of a fault where one taster reporting nothing is weak evidence of absence.
Chen, Zhao, Jiang, Liu, Cao, Ye, Mao and He, Foods 14(6):1005
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.
- Mould taint — Batch behaviour. Open a second bottle: cork taint varies bottle to bottle, a fruit or cellar taint does not.
- A dusty or stale glass — Pour into a second, freshly rinsed glass. Musty glassware is a surprisingly common false positive.
- Flat and lifeless — At low concentration cork taint does not smell musty at all — it simply strips the fruit out, and the cider reads as dull rather than tainted. A bottle that seems to have lost its aroma for no reason is worth checking against another.
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.
Trichloroanisole is formed when filamentous fungi methylate trichlorophenol. Chlorophenols arise from chlorine-based bleaches, sanitisers and wood preservatives reacting with phenolic material in wood; moulds present in cork bark, timber and damp storage then convert them into the corresponding anisoles. The methylation is a fungal detoxification reaction, and the product happens to be one of the most potent odorants known.
The human detection threshold is in the low nanograms per litre, which is to say a few parts per trillion. A quantity far too small to measure by any ordinary means is more than enough to spoil a bottle, and this is why the fault is so disproportionate to the amount of material involved.
The compound also acts as an aroma suppressant, apparently by interfering with olfactory signal transduction rather than only by adding its own smell. This is why a lightly tainted bottle tastes muted rather than musty, and why the fault is frequently misdiagnosed as a dull cider.
Related compounds behave the same way. Tribromoanisole arises from brominated compounds used in wood preservation and building materials and produces an indistinguishable taint, sometimes affecting an entire cellar rather than individual bottles.
How it happens
| Cause | Stage | How often |
|---|---|---|
| A natural cork closure carrying the compound | Packaging | common |
| Chlorine-based sanitisers used in a cellar containing wood | Maturation | occasional |
| Treated timber, pallets or crates in the storage area | Storage | occasional |
| Contaminated cellar air affecting bottles and equipment generally | Storage | rare |
| Wooden vessels contaminated at some earlier point | Maturation | 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 |
|---|---|---|
| Change closure for future batches | Reliable | Where the source is cork, this eliminates it. The commonest and most effective response. |
| Find and remove a cellar source | Reliable | Necessary where many bottles are affected. Look for chlorine-based products, treated timber and damp wood, and remember the taint can reach bottles through the air. |
| Remove the taint from an affected bottle | Not possible | The threshold is a few parts per trillion. Nothing available to a producer removes it, and folk remedies involving plastic film are unreliable and do not restore what was suppressed. |
| Blend affected cider away | Not possible | The threshold is far too low for dilution to work at any practical ratio. |
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
- Consider whether natural cork is necessary; crown caps and other closures remove the commonest route entirely.
- Buy corks from a supplier who tests for the compound, and store them somewhere clean and dry.
- Do not use chlorine-based sanitisers in a cellar containing wood.
- Keep treated timber, old pallets and damp crates out of the storage area.
- Investigate promptly if more than an occasional bottle is affected, since a cellar-wide source behaves very differently from a cork-borne one.
Cork taint is included here despite being a closure fault rather than a cidermaking one, because it is one of the few faults a reader is likely to meet as a drinker rather than as a producer, and because it is so often misidentified.
The aroma suppression is the part worth internalising. Most people expect a corked bottle to smell of wet cardboard, and a heavily tainted one does. A lightly tainted one simply seems to have lost its aroma, and the natural conclusion is that the cider is dull or too old. A bottle that seems mysteriously mute is worth suspecting.
The name is misleading in a way that causes real problems. Trichloroanisole is not a property of cork; it is a mould metabolite of chlorophenols, and chlorophenols come from chlorine chemistry meeting wood. A cidery that has never used a cork can still taint its entire production by using a chlorine sanitiser in a cellar full of oak.
For a small producer the practical conclusion is that closure choice removes most of the risk, and sanitiser choice removes most of the rest. Neither costs anything, and both are decisions made once.
Where in the process it arises
Closure selection
Choosing between cork, crown, screwcap, cage and swing-top, a decision that fixes how much oxygen reaches the cider, whether it can hold pressure, and which faults it is exposed to.
Bottling
Transferring finished cider into glass, where the dominant variable is how much oxygen the liquid picks up in the few seconds it takes to fill and close each bottle.
Sanitation
The cleaning and sanitising discipline that underlies every other process, and why removing soil must come before any attempt to kill organisms.
Cellar storage
Holding packaged cider in conditions that let it change slowly and predictably, where stability of temperature matters more than the temperature itself.
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.
Faults it is confused with
These present similarly. What separates them is set out on each page.
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.
Plastic and packaging taint
Plastic, rubber, adhesive or chemical notes picked up from unsuitable containers, liners, hoses, gaskets or cleaning residues.
Flat and lifeless
A cider with nothing obviously wrong and nothing to say: aroma faded, acidity dulled, finish short — usually the cumulative result of over-processing or slow oxidation.
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 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.
- How should i store cider — Cool, dark and at a steady temperature. Light causes light-strike in clear glass, warmth accelerates oxidation, and temperature swings push cider past the closure of a bottle that is not tightly sealed.
- What causes a flat and lifeless smell in cider
- Can i use screw top bottles for cider — For still cider, yes. For anything carbonated, a reused screw-top wine or juice bottle is not designed to hold pressure and should not be used.
- How is cider bottled
- 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 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.
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.
BJCP Beer Style Guidelines — cider and perry categories
Beer Judge Certification Program · classification framework · retrieved 2026-08-24
Opened on 2026-08-24, and the edition matters. CiderHQ registered the 2015 cider guidelines; BJCP has since published a 2025 cider edition, and the old URL now redirects into the current guidelines index. A competition style guide is a dated framework rather than a standing definition, and citing the wrong edition of one is the same class of error as citing a superseded specification. CiderHQ treats BJCP as one competition framework among several and never as the universal cider taxonomy.