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Corks Won the Closure War. You Lost

Science shows that we like wines sealed with corks because they sound better, which is fine, except when the wine tastes like soggy cardboard
They're charming, but they're spoiling a significant number of wines.
Photo by: iStock/KarpenekovDenis
They're charming, but they're spoiling a significant number of wines.

Posted: Dec 15, 2017 11:50am ET

By Mitch Frank

"Sales dropped. It was a disaster," the winery owner told me. Last year, I asked an Italian vintner if she had ever considered using screwcaps. That was the disaster. The winery had tried out screwcaps on its entry-level Valpolicella. Customers rejected the change; the decline was dramatic. After two vintages, the winery waved the white flag and switched back to corks.

To me, it was clear: The battle over how we seal our wines was finished. Corks won. And that means you and I lost.

Cork is an amazing substance. It's the Babel fish of wine—by some improbable chance, nature designed a tree with bark that is nearly perfect for sealing wine bottles, protecting the liquid inside and allowing us to age it for years, even decades. The cells of cork bark are lightweight, elastic and impermeable to air and most liquids.

More than 2,200 years ago, Romans were sealing jars of wine with cork stoppers, than slathering them with pitch to keep air out. The technology was forgotten during the Middle Ages, but when glass bottles came into fashion in the 17th century, corks proved the ideal stopper.

As magical as corks are, they have a fatal flaw. TCA, TBA and other compounds that can develop in natural corks (such as when plant phenols, chlorine and fungi all come into contact) can react with wine and ruin it. There is nothing worse than opening a bottle of wine and finding it smells of soggy boxes and tastes like locker room.

Actually, there is something worse—opening a bottle of wine that should be gorgeous and dynamic, but thanks to a small amount of TCA, it tastes as boring as the classifieds. When you taste a horribly corked wine, you send it back and ask for a good bottle. When you taste a slightly corked wine, you often assume that's just how the wine normally tastes and never buy it again.

The cork industry has worked tirelessly to improve cork production and wipe out the scourge of TCA. It has also worked tirelessly at marketing corks as higher quality, more romantic and more environmentally friendly than alternative closures. Cork producers' concern for the Iberian lynx is admirable.

Still, a significant percentage of corks are tainted. In 2016, Wine Spectator's Napa bureau tasted 5,065 wines sealed with corks and identified 3.83 percent as being tainted, up from 3.5 percent in 2015. If Amazon shipped products in boxes that ate the contents 3 percent of the time, people would head back to the malls. Yet we continue to demand our wines be sealed with corks.

I've suspected we're listening to our hearts, not our brains. But a recent study shows we're listening to the corks.

University of Oxford professor Charles Spence conducted a study of corks and screwcaps. Spence is a fascinating man, a psychologist who looks at how our senses all work together. He first grabbed headlines when he demonstrated that the pitch and volume of the sound of biting into a Pringles chip impacted how fresh people thought it tasted.

In the cork study, 140 people were asked to taste and rate two wines after having been played the sound of a cork popping or a screwcap being opened. They were then asked to open the bottle with the cork and the one with the screwcap and rate the wines again.

The two wines were actually identical, but participants rated the wine with a cork as 15 percent better in quality. We hear the cork pop, and our mind thinks the wine must be good. One important caveat: Spence's study was sponsored by the Portuguese Cork Association (APCOR).

I get it—corks do sound better, and the pulling of a cork connotes a special occasion, even on a typical day. But like many things in wine, romance and tradition are getting in the way of facts.

So here's my own experiment. The next time you buy a wine under screwcap, as you twist open the bottle, sing yourself a little song—operatically, like a country star or a yodeler, whatever you like. (I'm going to try to sound like Otis Redding and fail.) Perhaps, "This wine is TCA-freeeeeee!" or "This wine will taste the way it was meant to beeeeeeee!" And don't wave the white flag.

Take our poll: What's your favorite type of wine closure?

Harvey Steiman
San Francisco —  December 15, 2017 4:24pm ET
I can produce a very satisfying sound like a popping cork by forming an "o" with my lips and drawing my finger past the inside of my cheek. And then enjoy an unadulterated wine under a twist-off. No problem.
Robert Hoffman
Pittsburgh, PA, USA —  December 16, 2017 10:25pm ET
The ritual of cutting away the foil and removing the cork with skillful use of a corkscrew is all part of the ceremony and romance of wine. Of course, the romance turns sour when the cork breaks and you have to try to remove the broken piece still stuck in the bottle. I always end up pounding it down into the wine and trying my best to filter out the cork fragments when I pour. In truth, I generally enjoy this ritual (at least when it all goes well). Still, I’m never unhappy to open a screwcap bottle. That said, I would miss corks if they went away.
Adam Lee
Sonoma County, CA —  December 17, 2017 10:13am ET

I should begin by saying that I am a staunch supporter of twist-off closures, using them both for my Siduri Pinot Noirs but also for my new Clarice Wine Company winery. That out of the way, I have a few issues with what was written here.

First off, to cite a study that was paid for the Portuguese Cork Association as a science and evidence that demonstrates that "Corks Won the Closure War" is ridiculous. I doubt you would even cite a study paid for by a Pinot Noir Association that showed that 74 out of 140 participants (the 14% more in the "study") found that Pinot Noir was a better wine than Cabernet Sauvignon. This isn't science, it is sponsored propaganda.

Secondly, the blog ignores one other important consideration when looking at closures. Certainly TCA remains a major problem in cork-sealed wine (though it seems to be down significantly from some years ago according to Wine Spectator's ongoing statistics), but oxygen ingress is a problem not mentioned. Wine sealed under cork has huge variation in oxygen ingress rates, meaning one bottle may taste significantly more evolved than another bottle of the same wine opened at the same time. Twist-off closures reduce this oxygen ingress rate dramatically, meaning that the Pinot Noir that you enjoyed yesterday will taste much the same from bottle to bottle.

Cork producers were seemingly content for many years to sell a knowingly inferior product. Wine Spectator showed rates of TCA infected wines around 8%...this number has dropped to 4% now, still inexcusably high. What has led to this drop? I would posit it has been the success and acceptance of twist-off closures. Competition does amazing things! Perhaps with time and continued competition this rate can drop even further and perhaps even the oxygen ingress rate issue can be addressed. That would be fantastic for producers and consumers alike. But if and when that happens, I'd have a hard time arguing that "Cork won the closure war."

Adam Lee
Rebecca Poling
Detroit, MI —  December 18, 2017 10:07am ET
Nice Douglas Adams reference.
Tim Mc Donald
Napa, CA USA —  December 18, 2017 1:55pm ET
Boring as the classified section indeed. Nice story Mitch. I am a zero defect closure wine fan and I prefer Nomacorc which never has TCA or risky oxy permeability. I have always liked the twist off closure as well. Mild cork taint or ridiculously high TCA is unacceptable. Regardless of price point ladies and gents why haven't the smart wine producers migrated to a NO risk topper? Agglomerated corks can also be used to lower risk. Just last weekend we had a party The Grenache that stole Christmas. Guess what? 12 reds...2 with issues one oxidized [something we should be talking about in addition to TCA infection] There are a lot of innovative closures out there to pick from today. 3-4% failure, and I believe that it is much higher. Use a Nomacorc, a glass topper, or a guaranteed agglomerate. and if that's not ok, twistoff....Cheers!
Jack Erickson
Carrollton texas —  December 18, 2017 3:03pm ET
Corks, am willing to put up with occasional TCA for the ambience I get from opening a bottle. Wouldn’t disagree that screw caps work and are possible better,however I do not get the same pleasure unscrewing a bottle of wine as I do going thunthe ritual of pulling the cork
Andrew Walter
Sacramento —  December 18, 2017 4:07pm ET
One of my favorite topics! I am small winemaker (100- 150 cases per year). At our scale, screw caps are more expensive so I am forced to use cork. I agree with Tim the agglomerate corks have performed well. I "rigorously sample" :) about 8 cases of my wine per vintage with a failure rate (oxidation and cork taint) of ~1-2%. Not bad, but still that's 1-2 bottles per vintage of my hard work that gets dumped into the sink. SInce most commercial wines use regular corks, I prefer screw caps when available -- peace of mind, saves my sink from alcohol intoxication and much quicker for the wine to get from the bottle to my liver! That being said, I am in the obvious minority....in the current WS poll..91% of respondents prefer cork (5% under cap). One would presume the 6000+ respondents reflect the more educated consumers. Yes indeed...cork has won.
Charles Auclair
Woodinville, WA —  December 18, 2017 7:13pm ET
This assumes wineries do not switch to the fully tested corks now being offered by many cork suppliers that guarantee TCA below perceptible thresholds. I agree 3% or even 1% is too much to tolerate. It is possible to get to 0% if the winery really cares.
I personally prefer cork for consistent aging. Nobody has convinced me yet that screw topped wines age appropriately.
Lyle Kumasaka
Arlington, VA —  December 19, 2017 12:16am ET
Well now I feel lucky--I've never had a wine corked badly enough to throw out, and it's rare (less than once a year) that I run across a wine with any detectable cork taint. But setting aside the idiosyncratic experience of one consumer, if WS is convinced this is a real and significant problem, why isn't it using the best weapons at its disposal to fight it: ratings and reviews.

I searched the database (more than 367,000 reviews!) for the word "taint" and it returned 7 instances, of which only 3 were about the existence of the usual cork taint, and of these 3 none was more recent than the 1997 vintage. The word "corked" appeared 41 times, and not all uses of this word were in reference to cork taint. The word "corky" appeared 114 times, only 8 of which were in vintages since 2007. This is well below 3 percent incidence, so it seems that the vast majority of wines found to be corky either aren't reviewed or aren't described candidly.

A few 55-point ratings, or frank tasting notes listing all corked samples even if re-tasted, would do a lot more to discourage corks than hundreds of blog posts like this. It would also be more helpful to your subscribers, and would help bring market forces to bear in fixing the problem.
Al Martens
Penticton,BC —  December 19, 2017 2:42pm ET
I was always under the impression that cork isn't a perfect seal, nor was it intended to be.
Isn't there a minuscule amount of air that is exchanged through the cork? Isn't this why clean cork is excellent for aging wines?
With a screw cap, no air whatsoever can be exchanged.
What impact does it have on aging?
Mark Clodius
illinois —  December 19, 2017 7:17pm ET
Can't some clever person create a miniature speaker [ like in some greeting cards] installed in the screwoff closure,
that will make a "PoP" sound when the screw off seal is broken ?

Everyone will be happy !
Adam Lee
Sonoma County, CA —  December 20, 2017 11:45am ET
A couple of follow up thoughts:

Al, twist-offs have different liners, including saranex which allows consistent amounts of oxygen ingress. That's the key, consistent amounts. Screwcaps with these liners allow in approximately the same amount of oxygen as the best corks, on a consistent basis. Corks have a wider range of oxygen ingress rates and thus age far less consistently.

Lyle, I should probably let the Wine Spectator folks speak for themselves on this, but I don't believe that they print reviews of wines ruined by TCA because that isn't the wine's fault, its the the fault of the cork. So when they come across a flawed bottle they request additional samples. Each year James Laube writes a report on the corked bottles they experience. Here's a link to last year's blog: http://www.winespectator.com/blogs/show/id/Corked-TCA-Wine-Flaw-Laube

Adam Lee
Mitch Frank
New Orleans, LA —  December 20, 2017 12:55pm ET
Hey all,

First, thanks for all your comments. Obviously I was wrong about one thing - the war over closures cannot be over if the topic still incites this much discussion.

Harvey, thanks for all your coverage of this topic. Your blog on AWRI research - http://www.winespectator.com/blogs/show/id/42295 - convinced me that there really is no sound reason for choosing corks over screwcaps. And yes, oxygen issues can be nearly as bad as TCA.

Lyle, at Wine Spectator we ask wineries for two bottles of every wine they submit for review. If one tastes flawed, or even if the reviewer just suspects something is off, the wine is marked so that another bottle is included in a subsequent tasting. We want to judge and rate the wine at its best.

Rebecca, thanks for noticing that I am a geek.

Adam, I made it clear who sponsored the study. Spence is a reputable academic, and I do not believe the study was designed improperly. That said, the PURPOSE of the study was definitely biased - someone commissions a study like that because they know the sound of a cork being pulled makes an impression.

While I believe that cork producers have worked diligently to improve their products, with some success, I also believe that they have devoted a lot more energy to marketing, to convincing wine drinkers that high-quality wine MUST be sealed with a cork and that they risk looking foolish or cheap if they buy screwcap-sealed wines.

At the end of the day, it's up to journalists and winemakers to continue to work to convince people that screwcaps are good for wine, that buying a wine sealed with one is protection from flawed wine. You have obviously convinced your customers. New Zealand has convinced a lot of customers.

But does that mean most wineries believe it is too big a challenge? Is it easier to continue to use a closure that ruins some of their hard work?

Thanks again,

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