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A critic sounds off on corked wines


The subject of corked wine never seems to go away, and never will, as long as wine bottles are stoppered with natural cork.

Fred Swan asserts that the rate of flawed corks is 2%-8%. That’s a big range. I would shy away from the upper estimate, which in my experience is too high. But then again, people have different thresholds of perception for TCA. I think I’m pretty sensitive to it, but I’ve been at tastings where others (usually Dan Berger) detected (or claimed they detected) TCA and I didn’t. So.

Then there’s the Cork Quality Council. For as long as I’ve been aware of their activities (a long time), I haven’t had a particularly high opinion of them. Hard to say why, even after all these years. I don’t blame them, obviously, for being the vocal defender of the cork industry, but there’s always been something heavy-handed concerning the way they go about it.

Fred’s list of “things we don’t agree on” is too interesting to pass by. Here’s my take on his bullet points.

1. The percentage of wines in the market or consumers’ cellars suffering from cork-derived TCA contamination. I’d put it around 2%. It used to be higher, but I do believe the cork industry has made inroads in solving the problem. However, a single flawed cork is one too many.

2. How to measure that. There’s probably no reliable way to measure it. We’ll have to make do with anecdotal information, such as my estimate of 2%. That’s based on about 4,500 wines I taste a year.

3. How to define “wines in the market”. What’s so puzzling about this? Wines in the market means wines in the market.

4. The quality/validity of the cork industry’s supporting data, my data or just about anyone else’s. See #2, above.

5. The interpretation of their data or mine. What?

6. How bad the effects of TCA contamination really are on a wine as compared to other contaminations such as brettanomyces or dimethyl sulfide (obviously this would also depend on the level of contamination). TCA contamination is always bad. Sometimes it’s unbearable. We don’t have to get into the game of “which form of contamination is worse, TCA or brett?” It’s like someone dying of brain cancer who comes down with a case of anthrax. “Which do you prefer, darling, the cancer or the anthrax?”

7. Whether or not there’s any relevance to the fact that “corking” occurs after a winemaker has relinquished control of the wine, as compared to issues with fermentations, sulfides, brett, etc. There’s no relevance. I mean, if you get a horrid bottle of wine, who cares when it turned horrid? It’s just horrid, that’s all.

8. The significance of consumer preference in determining whether or not cork is the best closure for wine. Obviously, marketers have to take consumer preference into account. I don’t think there’s any question that screwtops are cleaner than corks. But it’s also true that consumers misunderstand screwtops and have for years. Why? It’s not the writers’ fault. We writers routinely tell consumers not to panic over screwtops, but they don’t listen to us. Put the blame on sellers, I say, especially merchants and on-premise wine servers. That’s where I think you get the attitude.

9. The pros and cons of alternate closures. I hate most of the artificial closures, especially those rubbery things, often luridly colored, that expand once you get them out, so you’re unable to restop the bottle. I’ll take a screwtop anyday.

10. The type of closure we would prefer to have on wine that we bought for our own consumption, whether immediate or after 15 years in the cellar. Here’s where we get into arcane discussions worthy of Talmudic scholars. Does wine age in a screwtop? I don’t know. Do you? I’m sure that studies will be brought to my attention proving every which way. All I can tell you is that there’s nothing romantic about opening a very old bottle and finding the cork a slimy mass of blackened, filthy goo.

  1. #8. The significance of consumer preference in determining whether or not cork is the best closure for wine. Obviously, marketers have to take consumer preference into account. I don’t think there’s any question that screwtops are cleaner than corks. But it’s also true that consumers misunderstand screwtops and have for years. Why? It’s not the writers’ fault. We writers routinely tell consumers not to panic over screwtops, but they don’t listen to us. Put the blame on sellers, I say, especially merchants and on-premise wine servers. That’s where I think you get the attitude.

    Steve you are so right here with your response… being in the retail and of things (and now radio also), the ones on the floor of that shop/retailer can be (are) the first line of defense for any type of closure .. they have control and in the end 90% have no idea of what it means to sell inventory… Screwcap or whatever… they do not get it … Business!! But they do get the Tude… what is up with that???

  2. raley roger says:


    Can someone out there comment on glass stoppers? Are those at all viable over time? Do they provide a sound, hermetic seal? And, lastly, is there porosity in glass? Thank you in advance for insights.

  3. Winemaker here. Steve this has been on my mind a lot lately, since reading Richard Smart’s comments the other day about the dinosaurs in the industry: glass bottles, oak barrels, and natural corks. Perhaps true in the long term for mass-market wines, but in my opinion never likely for higher end hand crafted wines. Give me dinosaurs.

    I like the flavor extracted into wine from that bark closure, as much as I like the flavors imparted by aging in oak cooperage. Both are nearly equally part of my general expectations of the sensory profile that defines most fine wine.

    Fine wines can evolve positively under a bark closure. I can say definitively that in the 20+ years I have been working with alternative closures, I have never (in my opinion) seen a single wine evolve positively. Plastic stoppers are a disaster – wines die under them after a year or so in bottle. Wines don’t die under screwcap, but they don’t get better – again, in my opinion.

    @Steve it does not surprise me at all that your rate of TCA encounter is about 2% – you taste a lot of wines. I can tell you that not all corks are equal. TCA occurs more frequently in technical and cheap corks, and (surprisingly) in the most expensive corks – though less so than in the cheap and technical closures.

    We open a lot of bottles in our tasting room and loosely track the frequency of TCA occurrence. It is somewhere around 1 in 400 to 500 bottles. That’s more like 0.2%. Nevertheless, since it is my choice to continue to use bark closures, I make it clear to my customers that I will mitigate their risk – I will replace any corked bottle returned to me.

    Finally, @raley roger – take a close look at those glass stoppers. There is no glass-on-glass sealing. There is a little ring of plastic that does the job – essentially the same as a screwcap, but with arguably better esthetics.

  4. John, it’s my experience that corked bottles can occur across the price spectrum, right up to the most expensive wines.

  5. “All I can tell you is that there’s nothing romantic about opening a very old bottle and finding the cork a slimy mass of blackened, filthy goo.”

    OMG Steve, are you actually making a case for a protective wax coat? Okay,okay I know better.

    In over 25 years of observation at the venerable OCFWC, we find most taint to be in the composite corks.

    I have used the best corks from Lafitte for over 30 years with but two TCA instances….called to our attention.

  6. When I first got in the business we had a horrid corker which would grind up corks unless they were liberally impregnated with paraffin. By liberally, I mean far more paraffin than was the industry practice, almost to the point that you could scrape it off with a finger nail. (Periodically, a big hunk of the stuff would accumulate on the corker and we would stop the line to remove it.) I hated that corker and hated the almost artificial feel of the corks. It seemed the wine during aging never entered into the cork, the bottom in contact to the red wine barely turned color. In well-chilled whites, the corks were almost impossible to extract, the paraffin creating an unbreakable bond to the glass. Had I my preference, it would have been to buy a new corker and untreated corks.

    But… I must have opened well over a thousand bottles of those wines over the years and have yet to encounter a corked wine. In addition, I have many of these wines remaining in my cellar and they have aged remarkably well. I don’t know if the absence of TCA is some interaction and bonding of TCA to the paraffin or it is just a matter of a physical barrier. (Polyethylene is sometimes used to modify the properties of paraffin, and we know of TCA’s affinity to saran wrap.)

    Also, the old paraffin wines are showing surprisingly little change in fill level. Normally, wines of 40 years age are often low neck or shoulder level in fill, but the highly paraffined corked bottles are still well in the neck. And never a slimey, or gooey cork. My guess is these traits are the result of a good seal and inert barrier.

    I’m not saying that cork producers should wax up their corks like snow skis, but after taking all the measures possible to prevent TCA in their corks, I think a coating that seals the cork and is TCA absorbing might be interesting thing for cork suppliers to consider.

  7. Steve,

    What other industry would allow packaging to ruin their products? Only mine. Corks are just packaging. Packaging with the potential to ruin the product they are used with. They were appropriate technology two hundred years ago. They are not now.
    They fail in the short term (TCA and other off aromas) and fail in the long term (goo and deterioration).

    Not only that, they require wines they are used with to have oxygen introduced at a point in the wine’s life where it does not want it. Think about a typical bottling line. The bottle is filled with nitrogen (so the wine filling the bottle doesn’t get a big oxygen hit), comes out of the filler, is leveled with another shot of nitrogen, then goes into the corker where a vacuum is drawn at the moment that the cork is inserted. (The vacuum is checked periodically with a needle gauge that is driven through the cork to verify a negative pressure inside.) That evacuated space must resolve over time – with the atmosphere surrounding the bottle – 20% oxygen, air.

    By contrast, wines bottled with screwcaps and glass stoppers are filled with nitrogen, filled with wine, then have the closure placed over the top of the bottle and secured. That leaves a nitrogen atmosphere at very near atmospheric pressure.

    There is now plenty of evidence of wines aging under screwcap (and a bit for glass stoppers), and the wines have aged much like one expects a wine to age, with the possible exception that the fruit tends to be fresher. We bottle with mainly glass stoppers at Sineann. First wine we put under glass stoppers we also did with cork. The wines under glass are so much better (fresher fruit, more intense finish, last longer after opening), that we wished we had switched earlier.

    Our TCA rate ran about 2% in our final years of cork. The ones that scared me were the ones where you couldn’t smell the TCA, but had the fruit stripped.

    YMMV, this is what we’ve found,


    Peter Rosback Sineann

  8. raley roger says:

    Okay…..okay….can I be star struck for a moment?

    PETER ROSBACK just commented here. That guy is legit!

  9. @Peter: Great comment on the other side of the coin. I value the positive extractables from cork, you value fresher fruit.

    Two points: 1) All packaging fails, sooner or later. 2) The vacuum under cork resolves very quickly with dissolved gases evolving from the wine in the bottle, not the atmosphere outside (unless the corker jaws are leaving a seam in the inserted corks).

  10. Hi Steve,

    Agreed – Fred has initiated an interesting discussion. I work with Nomacorc, which makes co-extruded (foamed) synthetic closures (NOT the plastic plugs) so I bring a bit of a different perspective on things.

    As Peter commented: “What other industry would allow packaging to ruin their products?” Couldn’t agree more. We wouldn’t accept this level of fault in the beer or juice categories.

    In our industry, packaging has the potential to be used as a winemaking tool – shaping the way, positively or negatively, that a wine evolves.

    Some winemakers, like Peter, like the way that a wine ages – or doesn’t – in a virtually anaerobic environment. That’s a winemaking choice that he makes, and is reflected in the wine that is eventually consumed.

    Others prefer the way that a wine evolves with small amounts of oxygen introduced over time. Each grape variety reacts differently to oxygen, and when compounded with varied winemaking styles, it becomes a complex process to know what packaging is best for a wine.

    I don’t believe there’s one end-all, be-all closure for a wine. We need choices, which, when supplemented by variety-based research, help winemakers create the wine that they’ve worked so hard to produce.

    Nomacorc does a lot of wine chemistry research with independent institutions like AWRI, INRA, Geisenheim, University Católica in Chile, and UC Davis (all of whom retain the rights of publication). Our enology team works closely with winemakers to practically apply this arsenal of knowledge in managing oxygen in wines.

    Happy to discuss further – it’s an important and worthy topic.

    Katie Myers

  11. to John Kelly — please check out Harvey’s blog on the spectator site for a complete review of Aussie research on screwcaps. Wine age better…much better…by all subjective and objective metrics. i wish everyone would switch….in the meantime, I specifically search out wines bottled under cap.

    And I too will give props to mr Rosback as I am a big fan of Sineann wines…just had a “Baby Poux” this weekend…very nice

  12. Kurt Burris says:

    I may be remembering incorrectly, but Dr. Ann Noble (UC Davis sensory professor) asserted that there was a genetic component to the ability to detect TCA which may account for Dan Berger picking up TCA in more wines than you Steve. At one of my client wineries we use twin tops (disks of cork with composite cork sandwiched between them) for our estate wines and solid cork for the “reserve” bottlings. My emperical observation is that there is a higher rate of cork taint in the more expensive solid corks, but still very low. Probably in the under 2% range. But, I still enjoy pulling corks more than unscrewing a screw cap or pulling out a glass stopper.

  13. Kurt, Jim Laube is the world champ when it comes to picking up TCA that no one else does.

  14. Kurt — is a 1/50 chance that the bottle of wine you just opened being undrinkable worth the pleasure of pulling a cork?

  15. I am in full support of screw cap myself. In speaking with a winemaker earlier this year about his use of screw caps and aging, he said that after tasting 6 vintages of his screw cap wines, that the wines are aging well. I trust his word.

    As time goes on, I guess we’ll find out just how long.

  16. Scott Mahon says:

    2% seems incredible high to me based on my experience. But, mine is not as broad across the spectrum of wines as Steve’s.

    #7 is extremely significant if you are buying your wine direct for, as John Kelly mentioned, the winery will mitigate the loss of corked bottles to the consumer.

  17. #10 – Well, yes we do know. Well at least in Australia we do. And I personally know. It’s a fact, wines age perfectly well under screwcap.

    What they don’t do is oxidise at a random rate.

    I’ll trade the pop sound for knowing my wine will taste exactly as the winemaker intended it to age anytime.

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