Is TCA stable?

[Tom Archer]

In discussions about cork taint, the focus is on weeding out bad corks through detection systems. I've never heard anyone say 'and we need to get the cork trees grown like they used to be'

Now we all know there was a period from the late seventies on when a lot of VP got bottled with poor corks - the port producers had grown accustomed to getting top corks at low prices and many seem to have been initially caught unaware after the merger of the cork producers, that the price they were paying was no longer buying the best product.

But aside from that, evidently corked bottles seem much more prevalent in younger bottles than among those over 50 years old.

A quick Google of 2,4,6-Trichloroanisole finds a bland reference to it being a stable compound - but fully stable? - over a period of decades?

Writers like Broadbent tend to weed out tasting notes of corked bottles, so it's hard to work out whether vintages like 1955 once had their 'fair share' of corked bottles - what is apparent though, is that corked '55s are very rarely encountered now.

- Could it be that TCA slowly decomposes??

[Andy Velebil]

Interesting question. Haven't given that any thought until now. I've never heard any winemaker mention that it self-breaks down and goes away with time. So I would have to guess it doesn't.

I would venture a guess that why we don't hear about corked old wines is exactly what you mention. Wine reviewers rarely ever mention a wine being corked, unless in discussing a tasting with others where a bottle is corked. So I'd venture to guess, pre-internet wine board days, there are few records in the public domain of older wines being corked. And I'd guess the overall percentage of people now opening really old bottles and getting a corked wine is statistically pretty low. Given that it tends to infect current bottles at a fairly low rate vs. how many bottles are bottled.

I guess one other thing to consider, pre-internet many people drinking wine probably had no idea what "corked" wine was. I mean even now very few people, in the overall scheme of people drinking wine, know what TCA is and can easily pick it out on their own.

What I would be curious about is how the cork was treated during the processing over the course of the past couple hundred years. I know it's changed a few times in the past few decades so I wonder what they used way back when. Perhaps it's similar to wineries who used bleach to clean the wineries and didn't realize that is something that causes TCA to flourish (why it's not used anymore in wineries).

[Tom Archer]

Just did a search of the TPF tasting note database for the word 'corked' - getting 272 hits

Biggest offenders by vintage are '77 and '83 and there are very few pre 1960. Also noticeable is that where bottles are over fifty years old, the wording tends to run along the lines of 'some thought corked' indicating a poor bottle with possible traces of TCA. Assertive statements of 'corked' are almost entirely confined to the under 40s (when tasted).

This hints at TCA decreasing in evidence at around the time port corks become fully softened, suggesting that once the cork has been fully leached, the chemical may not be stable in the body of the wine.

[Moses Botbol]

I have nothing to base this on beyond shooting from the hip, but I don't think TCA ever goes away totally. Maybe it breaks down over the decades, but will come back swinging once the wine breathes enough. Perhaps other terms used to define TCA before singling out by compound in older reviews? Maybe that flavor profile was more accepted 50-60 years ago as par for the course?

[Tom Archer]

Perhaps other terms used to define TCA before singling out by compound in older reviews?

Older reviews are not much help, as the bad bottles tend to go unrecorded. What is striking is the age spread of reports of corked wine on the TPF data when compared to the age spread of the bottles themselves, and also the nature of those reports. There is a pretty clear indication of cork taint fading after the corks themselves become saturated.

Aside from the fact that there was undoubtedly an era of inferior cork use, the only other factor I can think of that might derail the theory is the fact that tainted corks sometimes make an inferior seal as well. I'm not sure how many people are as religious as I am when it comes to drinking the most ullaged bottles first, but the practice of 'survival of the fittest' may also serve to reduce the number of surviving corked bottles.

If my theory is right however, bottles from one of the worst offending vintages of the last decade's notes - 1977 - should now be showing a gradually diminishing incidence of taint.

[Moses Botbol]

I'm not sure how many people are as religious as I am when it comes to drinking the most ullaged bottles first, but the practice of 'survival of the fittest' may also serve to reduce the number of surviving corked bottles.

I do the same, drink from worst to best.

[Shawn Denkler]

TCA in wine is often caused by the chlorine wash of the corks. Mold on the corks may react with the chlorine. Perhaps years ago the corks were just punched out of the bark without the use of chlorine. Treatment of the bark probably has changed over the years. The quality of cork may have been higher years ago when less wine was bottled. So many factors to consider.

I believe TCA is stable in wine but I've never heard of a study to check it's stability. Our noses are so sensitive to TCA that is can be detected as low as five parts per trillion. Even if TCA deteriorates, enough would be left to taint the wine.

[Tom Archer]

The quality of cork may have been higher years ago when less wine was bottled. So many factors to consider.

Look at the mass market - the supermarkets - and the rise first of synthetic corks and then of screw caps.. Natural cork closures have been steadily dying a death. I don't have the numbers, but I wouldn't be surprised if the use of natural cork has dropped by 80% or more over the past 50 years.

Our noses are so sensitive to TCA that is can be detected as low as five parts per trillion. Even if TCA deteriorates, enough would be left to taint the wine.

It's easy to think that something as potent cannot disappear completely, but it's a bit like Iodine 131 - the most feared component of nuclear fallout. This has a half life of eight days, so its easy to think that it will stick around to a diminishing degree for a very long time. However, even if the release amounts to a trillion trillion atoms, the very last one is likely to have decayed within two years..

[Shawn Denkler]

Look at the mass market - the supermarkets - and the rise first of synthetic corks and then of screw caps.. Natural cork closures have been steadily dying a death. I don't have the numbers, but I wouldn't be surprised if the use of natural cork has dropped by 80% or more over the past 50 years.

The amount of wine produced today around the world is vastly more than is was fifty years ago, so the quality of corks probably was higher. Yes the percentage of corks used in the wine industry now is lower because of other closure types but I believe (without researching it) that the total amount of corks used now is much higher and the quality is lower on average.

It's easy to think that something as potent cannot disappear completely, but it's a bit like Iodine 131 - the most feared component of nuclear fallout. This has a half life of eight days, so its easy to think that it will stick around to a diminishing degree for a very long time. However, even if the release amounts to a trillion trillion atoms, the very last one is likely to have decayed within two years..

You are comparing a known unstable radioactive compound (Iodine 131) to TCA which is probably a very stable compound. Many of us on this forum have opened bottles over fifty years old and found that the TCA has not disapeared. The original question on this forum was if TCA was stable. In the absence of studies we are all guessing. But my degree was chemistry and the molecular structure looks quite stable to me.

[Eric Menchen]

... I wouldn't be surprised if the use of natural cork has dropped by 80% or more over the past 50 years.

The amount of wine produced today around the world is vastly more than is was fifty years ago ...

The amount of wine produced and consumed today is about the same as it was fifty years ago. See, for example, page 4 of:
https://www.adelaide.edu.au/press/title ... -EBOOK.pdf

[Andy Velebil]

... I wouldn't be surprised if the use of natural cork has dropped by 80% or more over the past 50 years.

The amount of wine produced today around the world is vastly more than is was fifty years ago ...

The amount of wine produced and consumed today is about the same as it was fifty years ago. See, for example, page 4 of:
https://www.adelaide.edu.au/press/title ... -EBOOK.pdf

I've only skimmed it, but interesting that there was a spike that started in the mid 1960's and lasted through the late 1980's. I wonder what the catalyst was for that.

[Eric Menchen]

The amount of wine produced and consumed today is about the same as it was fifty years ago. See, for example, page 4 of:
https://www.adelaide.edu.au/press/title ... -EBOOK.pdf

I've only skimmed it, but interesting that there was a spike that started in the mid 1960's and lasted through the late 1980's. I wonder what the catalyst was for that.

I think there are two largely different trends at work. On the one side, in the US and a lot of the new world, there was a great expansion of wine drinking. Wine wasn't that popular in the US through the 1950s. It became more popular and more accessible with better quality domestic production in the 1970s. At the same time, a growth of middle class people in the US and in many other countries increased demand. Countering that trend more recently, traditional wine consuming countries like France and Italy have had a decrease in consumption. Drunk driving and health concerns are two of many issues driving this.

[Roy Hersh]

From empirical evidence, a story I've typed several times since FTLOP began.

More than two years before FTLOP's website began, in May 2003, I hosted a great Port weekend with many good friends from the USA, UK and Portugal.

Bartholomew Broadbent and both of his parents joined me, so did Richard Mayson, Dirk Niepoort, Jorge Serodio Borges (who was Dirk's assistant at the time), Jorge Moreira (RCV / Qta de la Rosa / Poeira) and Nicos Neocleous all flew across the pond for this event and quite a few American peeps who occasionally posted on this forum in the early days; including my good friend Eric LeVine, (CellarTracker was only in Eric's head at the time). Now done with name dropping, to mention my bad lesson with TCA.

There were three days and nights of fun Port related events. I was being inducted into the Confraria six weeks later, and did not want to bring a ton of great bottles over to Porto, so it was easier to have the people come here. It was 20 years since I had tried my very first Port and this was the biggest Port event I had held at that point in time and I was opening up a bunch of my very best/oldest bottles in my collection.

One late morning, while preparing for that afternoon's event I was opening up a 1908 Sandeman Vintage Port. I was using a device called Cork Pops which one of my guests had gifted me. It uses a needle to penetrate the cork, (almost like what Coravin is today). I got it through the crusty old cork of my 1908 and then when shooting in the inert gas from a small canister that is attached to the needle (This is long before my friend Mark T. developed the Durand) the gas is supposed to slowly push the cork out. Well the cork did not go pop, but my 1908 Sandeman bottle did!

It literally exploded in my face. So much glass and goop was stuck to my face and mostly my glasses, that I couldn't see at all. I took off my glasses and carefully a friend wiped my face, only to see that I was still holding the bottom half of the bottle, intact, and containing nearly 375 ml. of the contents. I was still in shock and friends around me were laughing like crazy and a couple were applauding. Clearly they had never seen this new device (I think Cork Pops may still exist, but I never touched it again!). I decanted the rest of what was left and the sediment was plentiful. It smelled great and I couldn't wait to bring the rest of it for people to try. I poured the balance immediately after removing the sediment, into a half bottle and put it in the fridge. A few hours later, I am at the event, and explain why everyone was going to get a short pour and after pouring the first glass, I could smell the TCA ... badly.

Adding insult to injury ... I think is a phrase that was coined by someone who saw my face at that moment. Devastated and embarrassed far more than when the bottle exploded, I couldn't believe this was happening. More laughter, from those who had been at my home earlier in the day.

So when I tell you that TCA doesn't "go away" ... I am a true believer from this 95 year old bottle, (at the time) that taught me that TCA doesn't go away with time in bottle. This was not the last time I learned that, but it was my first.

[Eric Ifune]

That was one evil bottle!

[Roy Hersh]

One I will never forget.