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Cork: equal time in the closure wars


A few weeks ago, I blogged on the closure wars, and specifically about Nomacorc, a plastic “cork.” While I was careful to write, in bold italics, “This is in no way a product endorsement of Nomacorc,” I was aware of the fact that my sources of information were representatives from Nomacorc. They did a good job pointing out the advantages and efficiencies of their product, and that’s what I reported on.

So it wasn’t completely surprising when a fellow named Dustin Mowe contacted me, asking if we could meet up so he could tell me the real,  natural cork side of the argument. Dustin’s president of Portocork America, whose website describes it as “the premier supplier of natural cork closures to the North American wine industry.”

Dustin drove down from Napa, where the company is headquartered, and we met at my office-away-from-home, also known as Whole Foods. (Full disclosure: I let Dustin buy me a medium soy latte.) I told him I was there to learn, not to take sides. This was an important ice-breaker, I think, because the cork people have felt a bit beleaguered in recent years, what with TCA being a problem and vastly increased competition from plastic “corks,” like Nomacorc and screwtops. Dustin was perhaps expecting to have to defend natural corks more than proved to be the case; I let him know right away that I have no great argument against natural cork, just as I have no great argument with screwtops or plastic closures in general (except the ones that swell up after you extract them, and then don’t fit back into the bottle).

It seems to me that every producer has to figure out what makes the most sense for his wines, economically, esthetically and technically. I’ve learned enough over the years to know there’s no perfect solution to the bottle closure issue. There always will be a certain failure rate for natural cork, in the sense of it being infected with TCA, just as there always will be a failure rate in automobiles and medical procedures. (Life itself, let’s remember, has a failure rate of 100%.) Hopefully, the failure rate in corks will be low. Dustin assured me the cork industry is hard at work on getting TCA down to as near zero as possible, and I have no reason not to believe him, since their livelihoods are bound up with finding a solution.

What is the failure rate of corks? Depends on whom you ask. My own experience is around 1.5%. It used to be much worse, maybe 10-15 years ago, so it seems like the cork industry is making progress. Dustin showed me a chart on TCA analysis in natural corks over the last ten years; the tests were conducted by a third party lab, ETS Laboratories, in St. Helena, so there’s no worry of bias. TCA, measured in parts per trillion, averaged just over 4.0 in 2002 and has steadily declined since, with 2012 averaging about 0.50. Dustin cited Christian Butzke, an enology professor at Purdue University: “TCA is no longer a major problem for the US Wine industry.”

So why do some people insist it is? Partly, I suspect, because minds are slower to change than facts. If a critic decided 10 years ago that cork taint was unacceptably high, he might not have changed his mind today. Dustin cited Jim Laube, from Wine Spectator, who’s been criticizing TCA in corks for years. For example, in 2007, Jim wrote, “Wine Spectator’s Napa office tracks the number of ‘corky’ bottles in tastings of California wines, and the percentage of defective corks routinely runs at 15 percent, which seems way too high to me.

Last January, Jim addressed the topic again, writing , “In 2011, out of roughly 3,100 bottles of California wine topped with cork (another 269 were topped with twist-offs), the percentage of ‘corked’ wines dropped to 3.8 from 4.8 in 2010—making it the best year since we started tracking this. In 2009, nearly 7 percent of the wines were corked, and in 2007, it was 9.5 percent.” Don’t ask me how the 2007 “routinely runs at 15 percent” squares with “9.5 percent in 2007” because I don’t know.

People do have differing threshholds for TCA perception, as for other compounds in wine, like brett. Jim’s schnozz may well be far more sensitive to TCA than most other people, including MWs, somms, collectors and winemakers. Besides, every form of closure has its issues. Screwtops can let too little air in, which can lead to reductive aromas. Plastic can give weird rubbery smells. Each closure also has its own environmental footprint issues, which I don’t intend to get into. There are economies that have to be considered by the producer, as well as image issues. Dustin told me that Bronco Wine Co. uses natural cork for most of their brands, even though cork on average is more expensive than plastic or screwtop, because the Franzias believe cork has a better image.

I emailed Joey Franzia about this, and he replied, “BWC [Bronco Wine Co.] % of sales is 2-4% of all case goods produced; consumers like the POP! And screw capped wines are received 50/50 by buyers as positive and negative, corks are natural, eco-friendly and biodegradable.  We do extensive cork testing minimizing TCA contamination with BWC wines.”

I do like the POP! with corks, and the pomp and ceremony of opening a bottle, particularly when I’m entertaining. My poor old fingers are getting a little rickety, after opening 100,000-plus bottles over the years, but that’s a small price to pay for all the pleasure wine’s given me. So you’d have to count me as a cork fan.

  1. If you will allow me, Steve, a little professional advice. As a wine critic, it is adviseable to claim extra sensitivity and lower thresholds in most to everything in wine. Tell me why I should take your advice on a wine if your schnoz isn’t any better than mine? It’s got a cork in it, so it must have some small amount of TCA, right? So relax…let your imagination go a little. You can smell it if you really try. It helps too if you complain frequently about this cross you have to bear, the difficulty of going through life as a wine taster, sensing these defects while others are oblivious.

  2. Thanks for the advice, Morton!

  3. Adam Lee/Siduri Wines says:


    I actually think we expect more than even the 1.5% rate of failure that you bring up. Last year Dianna and I bought over 100 gallons of milk (3 kids in the house) and paid a mere $3.50 a gallon for that milk. Had 2 of those gallons failed completely (spoiled, leaked, etc) we would at first complained to Safeway…and then ulimately stopped buying milk at Safeway. That’s my experience on a beverage that is far cheaper than wine….so with something much more expensive my expectations are simply much higher.

    That, along with 6 years of trials, is what has led Dianna and I to go with twist-offs for our wine.

    Adam Lee
    Siduri Wines

  4. All about personal preference for the consumer.. The Women do Love Screw Caps. Cheers!!!!

  5. To my mind the best closure is a DIAM cork. We have had plenty of problems with reductive aromas in reds and whites under screw cap. The DIAM closure allows us to match the oxygen transfer rate (they have 4 different rates currently) to the wine and they are guaranteed TCA free (I have never had a corked or perceptively fruit scalped bottle). Having bottled over 400 different wines from around the globe under various kinds of closures DIAMs have performed the best and are certainly the most cost-effective – you get $.75/cork performance for around 80% less. Yes, and, the customer gets the pop.

  6. george kaplan says:

    That remark about rickety fingers hit home.

  7. Don’t forget that wines bottled with screw caps can still be affected by TCA and the other related haloanisoles (eg TBA), albeit at a much, much lower rate determined by environmental conditions. There is no perfect closure. Cans, bags and cartons are also viable alternatives to cork and screw caps with pros and cons.

  8. Corks are the major source of TCA, but it can also be sourced from a number of things including barrels. The formation of TCA via chlorine and mold interaction is the reason wineries stay far away from chlorine products, but sometimes they are difficult to spot (i.e. some dishwashing soaps, sanitation sprays, etc.). So as Kyle pointed out, wines bottled under all closures can have TCA issues.

  9. Bob Foster says:

    I run 3 different wine competitions around the US. We’ve seen the rate of corkiness drop to about 2 per cent. The badly corked wines are easy to detect. It is much harder to find the ones with just a hint of TCA. Often Those wines are below most, but not all judges’ threshold detection level.

  10. Steve,

    In New Zealand and Australia the screwcorks are the biggest thing since gravity was invented. They keep the wines forever young with the same traits they had when bottled. Great for white wines and reds. It all depends on what you want from the wine in x+y years to come. Some folks love these wines that never mature/evolve in the bottle.

    Countless universities studies can be found on the web about the subject.


  11. CArlos, the Nomacorc people told me that many Aussies are moving away from screwtop due to problems. I can’t vouch for whether or not this is true.

  12. I wish someone (not necessarily here, but in one of these closure discussions) would lay out how much of the “positive” changes that happen in aging is aerobic and how much is anaerobic. That would add, I think, much to the debate on what properties (beyond low failure rate) we want in a closure.

  13. Are there conclusive numbers on the costs of using different closures? (Both costs to the producers, and costs passed on to consumers.) I think knowing these are important to this discussion.

  14. Carlos Toledo says:

    DR, i am far from being a winemaker, but to me you raise a great point. There are two types (that i know of) reactions inside a bottle.

    It seems any small, petty topic in the wine realm can feature endless spins and rights and wrongs. Amazing, entertaining, telling, leery, and awesome.

    No wonder many people stay away from wine when some potential would be fomenters are pure boredom when they talk about hard to define topics to the “outsiders”.

  15. James, in general, screwtops are cheapest, then plastic, then natural cork.

  16. Duncan Ross says:

    Unless people are being killed, it isn’t a “WAR”…….. (and hopefully they are not). The term “war” is also used for heated debates where people have emotional or “religious” reasons for a position, and cannot be dissuaded with facts (vendor XYZ vs Vendor ABC). Rather than using such a violent term for something that is really an academic debate, perhaps using more of an accurate headline, like “Equal time for cork in the closure debate” would be preferable.

    I am tiring of all the wars, from the one on drugs, poverty, gas guzzlers to the war on people with bad driving habits. It’s too many wars, too much fighting and not enough discussion and rational thinking. We are talking about a closure, and not at all life changing.

    Unless you’re not using cork, which shows that you are ecologically insensitive and……

  17. Carlos Toledo says:


    don’t forget that natural cork stands for cork made with ‘decent material’. There’s plenty of corks made with the great conglomerate technique and each cork is worth a few cents. The transport costs more than the cork per se, but the cork is still natural.

    I don’t recall seeing those lousy corks in the US market, though. They’re shipped more often to the 5th world countries in terms of wine, like the one where i live now.

  18. Peter Rosback says:

    Imagine a salesperson coming to your winery and proposing the use of corks as part of your packaging.

    “They are all natural, biodegradable and each and every one is unique!” Unfortunately, what we want in packaging is consistency.

    What other industry would put up with the failure rate of cork?

  19. What we are dealing with is an anomaly in the beverage world, a living beverage for the most part. Corked wine is a bad thing, but a closure that enhances the life of a wine is what is needed except for those wines that are meant to be drank within a year or so max, which is the majority of bottled wines. Most capsules and plastic corks are good for those, unless the winery chooses not to for aesthetic reasons. As Cameron mentioned above for proper wine development and a good level of consistency the DIAM corks are pretty much the best thing outside of good clean natural corks. Also as mentioned a winery should avoid all products with halogen elements I quit using them long ago and even would think to avoid halogen lighting in a winery. Also many pallets are treated, Wood with methyl bromide(sometimes stamped MB) and plastic ones with a variety of halogen (bromine & chlorine) element fire retardants as polyethylene is highly flammable. I started to move to plastic pallets and found that out and pretty much quit. Even water has to be watched as municipal water is treated with both chlorine and fluoride. It is not an easy thing to eliminate as a group of elements that may cause problems.

  20. David Vergari says:

    Peter Rosback’s obsservation is spot-on. Several years ago, a rep from one of the cork companies paid me a visit. After explaining the various improvements made to improve QC and address the taint problem, she declared that I should still expect a failure rate between 0.5% and 1.2%. My comment? “It’s a damned good thing youse guys aren’t making airplanes”!!!

  21. Juan Magalhaes says:

    DIAM is not a natural cork by definition, is aglomerated cork with plastic microspheres in the inside, it is not 100% natural cork

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