Corked wines - what's the truth?
by Tom Cannavan, 1999
This was a survey and a challenge to Wine Pages visitors: I'd like to get a feel for the incidence of "corked" wines
that people experience. Corked wines suffer from quite a specific fault: the cork is contaminated and a chemical
called trichloranisol results, giving the wine a very distinctive mouldy smell. There is no doubt that some people are
more sensitive to "corkiness" than others, and that many people confuse other "off" aromas in wine as
corkiness, when in fact it's not. But let me put my side of the story....
As a conservative estimate I would guess that I taste around 1,000 wines per year; certainly 70 or 80 per
month regularly. These range from "everyday" bottles to top wines from every continent.
For a long time I've wondered about my own, personal susceptibility to trichloranisol (cork-taint) in wines.
What has made me wonder is that the wine press often carries stories suggesting a high incidence - often
figures like 1 in 20, or even 1 in 10 bottles are bandied about. Now that means I should find between 4 and
8 corked wines per month on average. Truth is it's nothing like that: I note corkiness in maybe one or two
wines per month maximum
- in fact I can only recall 5 corked wines tasted in the past 6 months or so.
A few things have happened recently however to make me doubt that this is just my abnormally high
tolerance level. At a Judges' training day for the International Wine Challenge last year 3 corked wines
were deliberately included in 100 samples, with varying degrees of taint. I spotted them all. At Christmas, our fine wine
group had Château d'Yquem on a tasting - my table of 10 people were poured their samples and sat oohing and
aahing whilst all I got was musty cardboard. I spoke to the supplier (who was there at the time) and he
immediately withdrew all the samples from that bottle, all of which displayed the fault. There have been
other very similar incidents to this, suggesting that I in fact have a normal or maybe even low tolerance to corkiness.
So my question is this: what is your experience with corked wines? Do you find a lot of corked bottles?
Are you in, or do you know anyone in the restaurant trade and if so, what's the incidence of corked wines spotted by
I am not trying to deny the existence of "corkiness", nor diminish how frustrating it is when a cherished bottle
exhibits that dreaded, musty, dirty dish-cloth odour, but
I wonder if those with vested interests are deliberately talking-up the incidence of corkiness as a bit of
political lobbying. Is this just an industry ruse to take us further towards the disappearance of this
ancient method of closing wine bottles, to be replaced by something cheaper and easier to manufacture?
Bernard Leak, England
My recent drinking history has covered close to two hundred bottles. Of these, I have found one definitely
corked bottle and a couple of suspects. The definitely corked bottle was
at a commercial tasting. I was surprised that the bottle
which was replaced was not the one I had in mind (though I hadn't liked
that one much). It may have been a mere misunderstanding which we were all
too timid to complain of. This looks like evidence of something, but I'm
not sure of what!
Is the problem smaller than has been claimed, or is it more easily
avoided? Are unscrupulous penny-pinching bottlers blaming cork-growers
because they are themselves willing to pay less for bad cork?
Have you noticed that crown caps never seem to be given a chance at
all? I have never seen a consumer survey which thought to distinguish
between crown caps and screw caps, though the former are more likely to
be fully air-tight, have been used for years in the cellars of Champagne,
and do not require expensively moulded screw-threads on the bottle.
There are at least a couple of crown-capped bottles on UK retailer Victoria Wine's
shelves: "The Original Zin" (an Italian Primitivo) and "The Original S" (an Italian Chardonnay) - Tom
Mark Perry, England
On the subject of corked wines - I have only come across three in the last
10 years or so. One was at Christmas in a restaurant. It was a Bordeaux 1985. The only way I
can describe it was as treacle that has been badly burnt. Unfortunately, as
we were guests and the host had ordered the bottle as a "good number" I
didn't have the opportunity to see what it was. The restaurant changed it
after the wine waiter picked up the bottle and visually inspected it and
sniffed the top of the bottle. A bottle of Rioja - Grinon 1982 - was chosen
as the replacement and excellent it was too!!
The "treacle" description sounds suspiciously like a fault called "maderisation"
to me, not just corkiness? A maderised wine has over-heated in storage and literally cooked. Shows you what
a confusing subject this is! - Tom
Robert Callahan, USA
Identifying corkiness isn't simply a matter of getting the classic musty-wet-cardboard on the nose.
Sometimes the taint is more insidious than that, and seems at first simply to weaken the fruit of a wine
and to make it seem shriller and harsher than it normally is. Hours later it becomes apparent to everyone
the problem the TCA geek identifies immediately as TCA is in fact TCA, as the finish gets nastier and the
taint becomes more apparent on the nose.
It's also worth noting TCA isn't the only source of cork-failure statistics. Another is mis-seated or grooved
corks that lead to oxidation.
But as far as TCA goes, I tend to get them in runs. A few years ago I started keeping track of the bottles I
encountered and the number of those bottles that were marked by TCA. I did this for two years, just
making scratch marks for total bottles and another set for partial bottles. While I probably didn't include
every bottle, I had many, many thousands of scratch marks after two years. Wines I had identified as
TCA-corky came out to be something near 3%. The standard figures, depending on who figures, are
1-5% so this result falls well within that range. That's not an acceptable failure rate.
I actually like cork, and when a cork is good it does a remarkably good job. It saddens me that this
traditional form of seal is destined to be replaced. But it is.
A good point that industry quoted rates on "cork failure" might
include other faults, not just TCA contamination - Tom
Nick Alabaster, England
My tolerance level has been shown to be much higher than friends of mine, yet I too pick up
corkiness when others can't. I guess my tolerance level is somewhere around yours, possibly higher. I too
experience less corking than 5-10% (never more than a couple a month) but my total number of
spoilt/non-perfect bottles is around those figures (up to 3 or 4 a month).
Maybe it's just the over simplication of the statistics? ie, they group any unsatisfactory or less than perfect
bottle under the banner of 'cork taint'?
Manuel Camblor, Puerto Rico
While I find it hard to agree with a figure like 4-5% for wine affected by cork taint, I must say that I find an
amount of "corked" wines in my tastings that I cannot - by any extent of my imagination - call negligible.
Which could simply mean that I have a very low level of trichloranisol tolerance. Sometimes this puts me in
the kind of uncomfortable situation you described: with kind folks "ooohing" and "aaahing" all over a
wine I find unacceptably musty.
For what it's worth, doing research for an article I've recently spoken with several acquaintances in the
restaurant and wine trade here in PR and the Dominican Republic, as well as in Miami, and I've been told
by the restaurant people that the percentage of wine sold and then returned due to cork taint was indeed
negligible to them (about 1.8% on the average). Retailers painted a totally different picture. The four I
approached spoke of returns on anywhere from 0 to an alarming 7% of bottles sold. The merchant who
gave me this last figure has adopted a very dodgy policy for accepting returns which has cost him - at
least - my custom. Of course, down here a wine can be tainted by a zillion things (more often than not the
fault of poor handling by shippers, distributors, merchants and consumers alike) other than trichloranisol.
Many caveats become necessary...
Kathleen Brown, England
I find about three or four bottles a year which I judge corky - this on a tasting of anything up to 30 bottles a month. A friend
and I tasted a nasty one at a Roadshow and the rep looked disbelieving about the opinion of a "couple of Punters" but he
was grateful when he had a swig. I think many people are diffident of putting themselves out on a limb when faced with
so called experts in the trade. I have had to send only a couple of bottles back at a restaurant in my entire dining out life.
Luckily I have enough faith in my palate to ignore the mutterings about fussy women customers. The occurrence
seemed unusually high at the International Wine Challenge
(where Kathleen also was a Judge) but I put it down
to macho chairmen trying to be authoritative!! Perhaps there is a vested interest vis a vis plastic corks. I was idly
wondering to myself the other evening whether a wine would taste the same after 15 years with a plastic cork. - Tom
Stuart Yaniger, USA
The usual disclaimers apply - I'm in the business of trying to displace tree-bark cork, so please view my
comments in the appropriate context.
There definitely seems to be a difference in taint rate between different brands of cork. The best ones, which
are quite expensive, seem to give rates of 1% or so. These are hardly ever used, even in the high-end stuff.
The average corks seem to run higher, perhaps 5-7%. The really crummy ones are 10% or higher. Note that
these are not anecdotal but are the numbers reported to us by our investor and customer wineries - they gather
these numbers by careful analysis of huge numbers of samples by people trained to distinguish cork taint from
My personal experience (and I admit that I'm sensitive to threshold amounts of TCA which don't overtly smell, but
suppress fruit) is right in line with these numbers.
And a rhetorical question: if cork taint were a rare problem, why did wineries like Mondavi, K-J, Clos du Bois,
Beringer, and Sebastiani throw pretty large hunks of money my way to try and develop an alternative?
Stuart is the Napa Valley based inventor and supplier of the "NeoCork" one of the
top contenders amongst synthetic alternatives - Tom
Gregory Dal Piaz, USA
Interesting question. I used to own a restaurant with a fairly extensive wine list and found that many if not most
bottles returned as corked where, in fact, perfectly fine. It's impossible to say how many corked bottles
were enjoyed by my customers though. In my personal experience about one in 15 bottles has some degree of
corkiness to it. From group tastings I've found that I am very sensitive to this fault though. Your story reminds
me of a tasting of Ravenswood's wines and everyone was oohing and ahhing about the
Merlot. When the group dispersed I suggested to Joel Petterson that their might be a trace of corkiness to the
wine. He tasted it and concurred, immediately pulling the bottle off the table. Ignorance is, in fact, bliss I guess.
Melvyn Crann, England
I agree with you about the level of faulty wines. I taste around 400 - 500
a year and find only a few corked - fewer than those which are oxidized.
However there are occasional ones where I'm not sure of the fault. Last
month I took one of Oddbins' Greek wines back and asked them to taste it in
the store. Three of us agreed that it was faulty but couldn't identify the
problem. (Unfortunately a "good" bottle wasn't much better.) I suspect
that the presence of TCA in minute quantities may mar the wine without
producing a distinctive corked character. I've occasionally had an
expensive bottle which has been disappointingly "flat" in character which
I've suspected of being in this category.
A similar point to that made by Robert Callahan above and a very good one. "Corkiness" can indeed have a much more subtle
effect than full-blown "dirty dishrag" odour and can be quite difficult to spot - especially when you don't have a
"perfect" sample with
which to compare it. Probably, in that case, we can give the industry a few extra points: they are presumably using
techniques and experience which help them identify even "mild corkiness" in compiling their statistics, whereas
most of us just put "off" bottles down to "flat" or boring wine-making, when in fact it could be a cork problem.
Derek Wood, Scotland
I would say our return/reject rate is about 5% - but it seems to come in batches. We can go many weeks without a
problem and then have a few intermittently over the next few weeks (different vendors/different wines).
So the actual rate may be less than the perceived rate - and not all down to TCA of course.
My wife has a rare palate - but no outstanding interest. (What a waste : ) She can spot the faintest whiff of TCA, at
five paces. A great comfort to me when I am not 100% sure.
I've had no problems with the newer materials/methods and have rarely had a vendor problem when rejecting corked wines,
retail or restaurant, and none at all in recent years. We had an interesting experience in a well regarded establishment
last year. We returned three bottles of the same wine in a row before giving up and
changing to another wine which was ok. The wine waiter wasn't fazed at all!
David Smith, England
I am sure you are aware of the caves of Pierre-Jacques Druet in Bourgueil. No one who has tasted his finest wines
could doubt that these are the wines of a great, great winemaker and no one who has had the privilege of his generously
lengthy tastings and heard him speak passionately on the subject of wine could doubt his depth of
knowledge. You may be interested to hear of Pierre-Jacques experiments with cork.
PJ makes wines with a long life from vines of great age so the subject is dear to his heart. Some ten years ago
he began to experiment with corks and also the level of fill that will produce the perfect wine. He was
intrigued by the amount of evaporation that could be expected in a wine that needed ten years in bottle before drinking.
He laid down significant number of half bottles which had been filled to within 2, 5 and 10mm of the cork.
He wanted to arrive at an ideal distance so that after the ten years there would be an optimum gap between wine and
cork taking into account the fact that evaporation would naturally occur through the cork. We recently
sampled the same eight year old wine bottled with each of the original gaps and it was absolutely staggering how the
wines varied. We repeated the tasting with a second three bottle sampling and the results were exactly the same. The
glee in PJs face when his points are proved is a delight to witness.
He had also repeated the experiment (same wines, same vintage) but using 24mm (the standard, I believe) and
25mm diameter corks to get an understanding of how much air actually passes through more or less
compressed cork and how that effects evaporation.
Finally, he had experimented with plastic and natural corks. It was here that the most striking difference was found.
The plastic corked wine had a lifeless quality - these things are of course all relative, I don't think PJ
could make a bad wine - but the naturally corked wine had a vitality and roundness. The point of course is that unless
you had tried exactly the same wine in the bottle with natural cork, the plastic cork wine would have tasted wonderful.
Where does that lead PJ? Well firstly, he buys only the highest grade of cork. An extra Franc or two for a better quality
cork in a wine that might retail for 70ff is a sound investment to him. You might as well not use
clean bottles as not take great care to select the finest grade of cork. He visits the cork producers to ensure he is buying
only the best. He uses a supplier that now utilises a device not unlike a hot-plate. When a cork is briefly rested upon the
plate it releases an odour and to the trained nose a suspect cork is easily identifiable and discarded. Of course
it increases the cost and I suppose you might argue that PJ is a purist, but I do believe that if we simply accept the
argument for plastic corks and other short cuts in the pursuit of higher profits through lower reject rates
without exploring options, then the world of wine will be a poorer place.
Thanks to David for a fascinating and nicely told bit of real-life perspective.
The quality of the cork and the price winemakers are prepared to pay is surely close to the heart of this issue. - Tom
Walt Carpenter, USA
Couldn't help but respond to your question on "corked". I think the % is very low, something around 1-2%. I
also think that this is a fashionable topic and people want to say the wine is corked. The d'Yquem you refer to was not
thought to be corked by most people because they were drinking the label which I think is VERY common.
People also seem to confuse Corked with Brett which I still don't totally understand but believe them to be
different problems. My experiences are very close to yours.
"Brett" is short for Brettanomyces, a rougue yeast that can impart a mousy, mouldy
aroma to wine. - Tom
Graham Simpson, England
I have just read an article that was published in Wine Spectator Online (Jan 9th, 1999). It shows that corked wines are not due
solely to TCA formed by cork-moulds. The article effectively went as follows:-
Many cite the "corkiness" culprit to be the chemically treated wood used for cellar construction, wine bottle bins and other
purposes inside wineries. This problem, although known for years within the wine industry, recently became more public due to
reports in the French newsweekly, L'Express which showed that US, Spanish and Australian
wineries had also been affected. Vintners in France and elswhere believe that part of the problem of corked wines stems from
the cellar conditions; the presence of a group of chemicals called polychlorophenols (PCPs), especially pentachlorophenol,
which are applied to wood in a preservative against mould and insects.
In Bordeaux, many Châteaux have replaced roofs and walls in wineries since PCP molecules emitted from the wood into the
atmosphere under humid conditions will cause the chemical conversion from PCP into tetra- and pentachloroanisoles,
which are similar to 2,4,6-Trichloroanisole and have greater melting and boiling points to boot. These contaminants
migrate into the wine; work performed by French researcher Pascal Chatanet and other researchers have found that barrel +
vat-aged wines, along with corks stored in a cellar and even bottled wines have been affected.
New wineries have been hit harder than old ones; new materials only recently treated with chemicals by the wood suppliers.
Air conditioned cellars speed up air pollution also. Two examples:-
1. In 1995, Domaine du Grand Vendeur in Châteauneuf-du-Pape destroyed all its wines after a new cellar contaminated it.
2. The quality of the Château Canon (St-Emilion) wine dropped considerably from 1992 to 1995 with bottles showing a dry and
cardboard character. The problem was attributed to a chemical containing polychlorophenols used in the roof and wall wood.
The Conseil Interprofessional du Vin de Bordeaux estimated that less than 1% of cellars were PCP-affected. Also, they performed
a taste test on 1,344 wines, with 44 showing corked characteristics (3.27%). Wine Spectator themselves found that between
3-5% of the thousands of wines tasted each year were corked.
As an aside to this, many people have talked about use of "plastic corks". With particular reference to David Smith, who mentioned
research by Pierre-Jacques Druet. It seems fair to expect that since plasticisers are used in these corks, that over time the contact
with the alcohol (ethanol) some of these plasticisers may leach out into the wine, thus leading to the limp flavours characterised.
Conversly, the wines closed with cork showed vitality and roundness, as expected. This shows that perhaps the solvent effect of
the ethanol in wine extracts flavour/aroma compunds from the cork (as well as TCA) to enhance bottle maturation.
Rod Richmond, England
We drink over 150 bottles of wine a year at home in the under £5 range. I believe we have had four or five wet cardboard
wines in the past couple of years. The freshly extracted cork usually sorts the wine in seconds if it does not
inspire as to the pleasures ahead.
I have two observations on frequent problems I have encountered with wine.
Firstly Pinot Grigio has a high failure rate for being metallic. Secondly,
cork related problems seem to predominate in supermarket purchased wines in
Spring and Autumn. Could this relate to the budget transport arrangements
being tuned to the previous Season, e.g. cases left in a corner which is
cool in Winter but hot on a sunny Spring day or conversely cool in Summer
but frosty on the coldest Autumn morning?
Richard Duguid, England
Have just read the contributions on corked wines, and thought I would add my
ha'pennyworth as an inexperienced novice. First I calculated how many
bottles of wine I tasted (i.e. drank, but obviously shared with others) each
year and was so staggered by the result that I had to lie down for a while
and consider joining AA. My estimate is that I
have tasted getting on for a thousand bottles of wine over the last year. My
recent experience is that we have approximately one corked bottle a week,
which is one in 20, which is ... blimey, 5% - pretty much the favoured
figure of the anti-cork lobby. And more often than not we have had a 'good'
bottle for comparison, so despite our lack of well-developed palates I
reckon we're usually right.
I'm not surprised that 'returns' figures in restaurants are much lower than
this. Unless you're very confident it's embarrassing. I know it shouldn't be, and as
I get more sure of what a particular wine really should taste like I'm sure
I will cope better. Taking a bottle back to Sainsbury's or Oddbins is of
course a different matter. A friend of mine took an empty wine bottle back
to Sainsbury's the morning after he had consumed its contents and complained
that it gave him a headache. Since he always drank a couple of bottles every
night and hadn't had a headache in years, he put it down to the wine being
off. Result: full refund!
Peter Cartledge, England
I am a little puzzled by the need for so much debate on 'corked wines'.
It is statistically a small problem, so does it matter? Surely if a wine is 'off' in any way, send it back whatever the problem. End of
story. No further debate needed. In 35 years of wine drinking, I have come across wines I have
had to send back, for a variety of reasons. I have had problems with cars too but I don't feel the need to debate the subject.
Surely there are more interesting and less academic subjects to discuss than the occasional incidence of corked wine?
I do take your point - that corked or otherwise spoiled wines should be accepted as such by the supplier and replaced,
and usually are. However, I wonder why the subject is being so continually trumpeted in the press and why sectors of the
wine world are spending so much money trying to eliminate a method of closing bottles that has served us well for centuries.
Even a 1% spoilage rate is unacceptable: if any other food product was sold with a significant amount of
faulty packaging there would surely be a scandal about it! But at the same time the replacements for cork - plastic, metal or
whatever - are not proven to my satisfaction as sympathetic closures for fine wines destined for cellaring.
The great push that currently exists in certain sectors of the media and industry towards replacement of cork
makes me rather nervous. Shouldn't the money be pumped into eliminating problems with cork? - Tom
Michael Donohue, Canada
I buy wines in Ontario and sample 1-2 bottles per day and have had a spate of bad bottles recently, ranging from Chilean
cab (Gato Negro, normally a safe bet and the '97 Carmen reserve, which wasn't "corked" but painfully
acidic: it actually hurt my gums and I don't think it was an excess of youthful tannin), to Luc Pirlet cab ( a negociant in
Languedoc, corked; his Syrah-Mourvedre is wonderful) and Huet Vouvray Le Haut Lieu '96 (one bottle
in a class fine, the other corky). My guess at the rate of corked wine is 3-5%, although I would be the first to admit that separating
corkiness from other faults is not always easy. It will be interesting to see if artificial corks eliminate the problem, though I find
them exceedingly difficult to remove from a Screw-pull
Totally agree on the steroid-driven gripping power of some synthetic corks: one stopper from a bottle of Chilean wine caused me to
retire my trusty Screwpull when it stuck so fast I snapped one of the plastic legs levering it off! - Tom
Chris Bridges, Germany
As a regular wine drinker in Germany I thought I should perhaps comment on the increase of corked wines. I would say in my experience of wine
tasting that there has been an increase in the number of corked bottles over the last 5 years. I would fully agree with estimates of 2 to 5% .
Again as one of the other tasters points out my wife can spot a corked bottle at a mile (Perhaps the female palate is more attuned to TCA?).
We buy most of our wines directly from the producer but still, especially in the summer months, we have a number of bottles which
have to be exchanged. Recently the owner explained that he had tried all types of corks but still had a problem. However help is on the
way through a joint collaboration between a Wine Institute in Rheinland-Pfalz and a commercial firm (With EC assistance).
They have developed a new microwave technique that heats the inside of the cork to a temperature
which destroys the fungi and the fungal spores. The sterilization of corks is much more easy and long-lasting. The new method
is being patented at the moment and should not add to the cost of a normal cork. Of course what happens after they are delivered
and placed in the bottle remains open to re-infection, but it does look like help is on its way.
Interesting Chris. I wonder why the summer bottles are more prone to corkiness? Could they also be suffering heat damage if
improperly stored at the winery I wonder. I believe there are various cork-sterilization techniques being developed which, if they work,
would be the ideal solution IMO - Tom