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Cork Taint in California Wines Hits New Low

Our informal tracking of wines flawed by TCA reveals lowest rate since 2005
Photo by: Greg Gorman

Posted: Jan 4, 2013 12:00pm ET

The number of California wines flawed by apparent cork taint (2,4,6-trichloroanisole, otherwise known as TCA) fell in 2012 to its lowest level since we started informally tracking this controversial issue in 2005.

Roughly 3.7 percent of the 3,269 cork-sealed wines from California that we tasted in the Wine Spectator office in 2012 were thought to be tainted by a bad cork. It's not a scientific study, since we don't test the corks or wines to determine the cause. Yet the Wine Spectator editors who review California wines keep track of how many we think have an obvious TCA character. Many other wines may taste off as well, though it's less clear why. Our bottom line is, any wine thought to be off for whatever reason is automatically retasted. Of note, nearly 300 of the California wines we tasted in 2012 were sealed with twist-off closures.

That the percentage of TCA-tainted wines in 2012 is the lowest we've seen (down from 3.8 percent in 2011; the highest level coming in 2007 at 9.5 percent, or a 1-bottle-per-case average), it presents both a case for those who claim cork quality has improved (as it would appear) and that there is still a problem. Many of us believe no wine should be tainted by a bad cork; most of those who subscribe to that advocate alternatives, primarily the twist-off closure, or screw cap, but there are numerous alternatives.

TCA-taint, though, is only one of cork's problems, as I was reminded over the holidays. A friend asked me to bring some mature wines to a dinner this past week. All four of the older wines (including a charming 1981 Opus One and a potent 2001 Schrader Cabernet) had their corks either split in half or crumble as they were removed (even using an ah-so). The 2001 Paloma Merlot was corked, undrinkable.

The question becomes, is the 3.7 percent cork taint a victory for corks, or a reminder that there is still room for improvement, if not near perfection? Or is it a non-issue?

Todd Bishop
San Francisco, CA —  January 4, 2013 1:49pm ET
For older wines, I highly recommend checking out "The Durand" corkscrew: Its design functions to use a basic corkscrew and an ah-so simultaneously, which helps to hold fragile, old corks together in once piece. It's a pricey gadget (much like the original "Rabbit" corkscrews were when first released), but well worth it, I think, relative to preserving the integrity of mature--and often, equally expensive/valuable--wines and ensuring a headache-free experience.

(Note: I'm not affiliated in any way; just a happy customer!)
James Laube
Napa —  January 4, 2013 1:52pm ET
Thanx, Todd. Will give it a try...
Andrew J Walter
Sacramento, CA —  January 4, 2013 6:05pm ET
Of the 300 wines tastes from screw capped bottles -- what percent were "automatically retasted" due to potential flaws?
James Laube
Napa —  January 4, 2013 7:05pm ET
We retasted seven twist offs of the 300. A couple were oxidized; others just to double check our first impressions. I'll have more on the bigger picture of closures soon. New world (led by New Zealand and Australia) led the way with twisties while the most traditional regions (Italy, Spain and France) had the fewest.
Don Rauba
Schaumburg, IL —  January 4, 2013 9:47pm ET
Well I'll be looking forward to the "improvement" in 5-7 years when I'm finally opening bottles from these vintages. The stuff I'm opening from 04, 05, 06, and 07 is still killing me with disappointments. Oh, and because these winemakers are that stubborn (yes, because the scientific evidence is there to support ageability of alternative closures, so only stubbornness chooses to ignore it) I don't buy their wines any longer. I'm looking at you, Turnbull, Ravenswood, Pine Ridge, Columbia Crest, Argentina & Chile... et al...
Brian Loring
Lompoc, CA, US —  January 5, 2013 3:51pm ET
Jim - thanks for continuing to shine a spotlight on this issue. I'm somewhat surprised that more domestic wineries haven't switched over to screwcaps, like we did with our 2004 vintage. For a while, there was gathering momentum towards screwcaps, but it seems like that has recently waned a bit. At least a few wineries are still joing the "movement", so big props to Adam and Dianna Lee at Siduri for going 100% screwcap with their current release.

Even if TCA rates have fallen, I'd still be unhappy producing a product with a failure rate of "only" 3.7%. Especially given that the previous year's stat was 3.8%. Granted it's not a lot of data to go on, but does that mean we've reached a leveling off point where that's the best the cork industry can do? I'm not impressed.

Jim Mccusker
Okemos, MI —  January 5, 2013 5:21pm ET
Jim and Brian - Here is my question concerning cork versus screwcap closures (and I'm looking at this from the point-of-view of my profession, which is Chemistry). With the presence of sulfites in virtually all wines, I would presume that the conditions inside the bottle lend themselves to what would be called a reducing atmosphere. Over a long period of time, it seems to me that slow diffusion of oxygen through the cork gradually changes the conditions in the bottle from reductive to oxidative. This could not happen with a screwcap closure.

Perhaps it's the case that the amount of air associated with the ullage is enough to oxidize the sulfites to sulfates, but I would think that over a 10, 15, or 20 year period (depending on the density of the cork which will affect the rate of oxygen diffusion), the net chemistry taking place in the wine has the potential to be fundamentally different with screwcap versus cork.

I know several wineries have been experimenting with this issue (Plumpjack comes to mind - I seem to recall them offering a 2-pack reserve: one cork closure and the other screwcap); I've read reports where the screwcap wines tasted "fresher" after some time, but I don't know what the emerging consensus is. Seems to me if you're going to drink a wine within, say, a 5-10 year window, go with screwcap and leave the high-quality cork for wines meant to be laid down for longer periods of time.

Any thoughts on this issue?
Brian Loring
Lompoc, CA, US —  January 5, 2013 6:38pm ET
Jim M - we use a liner that (if you believe the brochure) allows oxygen transfer similar to cork. So far, we haven't had any issues with sulfides/reduction. In any case, reduction is a winemaking issue. Even if a screwcap does cause the issue to be more noticeable, the problem isn't with the closure, it's with the winemaker.

And our wines do age under screwcap. While we didn't do "real science" by bottling both cork and screwcap versions of any of our wines, we can compare our wines vs wines made from the same vineyards by other wineries that bottled under cork. And when we've done that, we've seen the same general characteristics of aging - and at the same rate. I know it's only anecdotal, but it's pretty much convinced me that we made the right choice all those years ago switching to screwcap.
Adam Lee
Sonoma County, CA —  January 6, 2013 8:53am ET
Jim M - there was a study published in Practical Winery & Vineyard awhile back (one that actually wasn't paid for by one side or the other) looking at oxygen ingress in various closures.

Cork had a very wide-range of oxygen ingress (disturbingly so, IMO, as it meant that bottles could show very differently over time). Bottles with Twist-Off closures and Saranex liners, which allow in oxygen, had a much more narrow range of oxygen ingress with the top-end of the oxygen ingress level being at the very bottom of the cork range (btw, this is different than the producers of Twist-offs generally claim which is a consistent level of oxygen ingress). And Twist-off bottles with tin liners showed very little oxygen ingress.

So, from what I have read (and experienced in side by side bottlings we have done), your concerns regarding O2, sulfites, and closures shouldn't be an issue with Saranex liners.

One last complicating point, however, is that all of the studies I have seen are based on bottles that have been pulled from the bottling line and kept in perfect conditions. I'd love to see some oxygen ingress studies on bottles with various closures that have been shipped around the country, banged up in transit, experienced temperature variation, etc. That would be more helpful to see what customers are really getting out there.

Adam Lee
Siduri Wines

Andrew J Walter
Sacramento, CA —  January 7, 2013 12:41am ET
Adam -- based on the limited data from WS, the "clinical failure rate" of screw caps is about 1% (vs 4% with cork). That translates to about 1 failed bottle every 8 cases vs every 2 cases. This is certainly one of the reasons I buy your and Brians wines with regularity.
Coman Dinn
Prosser, WA —  January 7, 2013 10:41am ET
At Hogue Cellars we have been researching screwcaps in depth since 2001 due to concerns with the available alternatives. Per Adam's comments above we found that Saranex lined screwcaps admitted around half the amount of oxygen as an "average" cork or close to that of a very "tight" cork. In 2005 we started an ongoing comparison of our upper-tier red wines in screwcap vs natural cork and by 2011 were convinced that wine quality would be improved and consistency well served by moving those wines from natural cork to screwcap with the Saranex liner. We found that by making sure that the wines were fully aged in the cellar as well as slightly lower bottling SO2 we did not encounter issues of reduction in finished wines. An abbreviated version of the study is available at www.twistopenhogue.com.
Plumpjack Winery
Oakville, CA, USA —  January 7, 2013 5:24pm ET
We feel very strongly that any instances of cork-taint are unacceptable! Years ago, we posed the question, " Why do we accept ANY incidence of cork taint?" In response, we did what no one else was doing in the Napa Valley at the time, and bottled half of our 1997 Reserve Cabernet Sauvignon under screwcap. While we did not conduct an intensive investigation into the oxygen ingress of cork and screwcap at that time, however, we are currently donating wines to UC Davis so that they can do just that. But, regardless of what those studies find, we have found that our wines show very well under both cork and screwcap. Our wines bottled under screwcap are very consistent, are not reduced, and, obviously, never corked. We have also found that they are aging quite well. It seems to me that screwcap is a very viable alternative to cork. While many of our regular customers now request our Reserve Cabernet under screwcap there still exists the challenge of convincing the broader consumer and restaurants to do the same. -Aaron Miller, Winemaker
Brian Loring
Lompoc, CA, US —  January 7, 2013 7:22pm ET
Aaron - what you guys did in 1997 at Plumpjack was potenially game changing. Hopefully, it will be eventually remembered as important as the 1976 Judgement at Paris. It took real guts to bottle the winery's best wine under screwcap. And all of us who have followed owe a big debt to Plumpjack.
Lyle Kumasaka
Arlington, VA —  January 7, 2013 11:10pm ET
Frankly, one of the reasons I subscribe to the magazine is so that you can identify for me the wines that are less likely to be flawed (for any reason). I rarely buy a bottle that has not been reviewed by WS or another major publication, and my corked rate is well below 1%. So thanks!
Karl Mark
Illinois —  January 8, 2013 7:16pm ET
Thank you for keeping us, the general public, informed about cork taint. I always enjoy reading these blog entries. Furthermore, if given the option i would choose any closure over cork. I have evolved.
Robert Lapolla
san diego ca —  January 16, 2013 1:14am ET
What's the difference between funk and taint?? I have had wines that are funky , barnyardy - is that taint? I think it's bacterial. I don't like it and I return them. If I get the same wine agin and it's funky I know it's not the cork. It still sucks. Back it goes again for something else. Two I recently had that were funky we're spring mountain cab 2006 and Joseph phelps cab 2006. Sometimes it blows off ( bottle stink) but usually not. Whitehall lane reserve cab comes with a nice glass stopper I really like. I used to like st Francis plastic corks but they stopped using them and switched to real cork - why? Cheaper? Some people did not like plastic touching the wine. I mean come on. I agree the incidence of corked wine is way down. I also note the price off cab is way up. Consumers are paying for cleaning up dirty wineries. I hate to say it but I like real corks. It ain't soda. Apologies to plumpjack, my favorite cab . I never had a bad bottle of plumpjack. When plumpjack had their restaurant in San Francisco, plumpjack was the house wine!! The waiters would whip out the corks in those bottles and slosh it into your glass almost to the brim. I guess that's why it went out of business in the recession.
Wayne Stanley
Calgary, Alberta Canada —  January 16, 2013 12:39pm ET

I've followed your discussions on TCA for some time and as the occasional consumer of tainted wine I share your interest in reducing thhis blight on wine quality.

I have come across a technology through a fellow in our office that I thought you might be interested in. My interest was in the application of the technology to reducing bacteria in hospitals but I saw the application for bacteria and fungus control in wines, based on some successes that the application of the technology has achieved in removing bacteria, funggi and spores in brewery operations.

Would you be interesting in taking a look at it as background to your on-going interest in managing TCA?

I have not been able to figure out how to contact you otherwise so I have taken the liberty of sending this note via the comments feature of your blog.

If you are interested I can have my associate send you some informnation directly. He would be able to provide more specific information. Let me know at wstanley@encantopotash.com

best regards,

Wayne Stanley

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