Corks Dont Get Me Started

Some time ago I attended a symposium in London on the subject of wine closures. The panel discussion concluded a seven-year debate on the pros and cons of different wine closures. The panel consisted of four world-renowned winemakers and was moderated by wine writer Jaime Goode. The winemakers on the panel were all southern-hemisphere new world winemakers but they all unanimously condemned natural cork as a product that belongs firmly in the past. 

What has cork done to receive the anger of such a distinguished panel? Well, firstly, there is the age-old problem of TCA, 2,4,6 trichloroanisole, a chlorine-based compound which can be detected in the most minute quantities and gives the wine an off-smell likened to a dank basement or mouldy socks. Despite the best efforts of the cork industry TCA in corks hovers at about 3%. 


Further problems with natural cork can be as follows:


Random oxidation; in order for corks to work optimally they need an internal moisture of about 5-7%. Any less and they lose the springiness needed to seal the bottle. If that seal is lost then it will lead to ingress of oxygen into the bottles and oxidation of the wine. Oxidation of wine is similar to watching an apple go brown; the wine goes brown and loses its life and vibrancy.


Flavour Scalping; the cork absorbs some of the volatile aroma compounds in the wines thus changing its character.


All of the above factors lead to probably the most insidious problems of natural cork and that is bottle variation, meaning that in a batch of wine that was bottled all on the same day there will be a variation in the quality and the consistency of the wine leading you the customer to drink a product which wasn’t entirely what the winemaker intended you to drink.


The other problem with natural corks is the people who make them. To this day I have yet to meet a cork supplier who was willing to take responsibility for the damage he caused to my wines, or anyone else’s for that matter. I estimate that in the years that I have been in business a corks have spoilt about quarter of a million of those bottle that we made. If we do a quick calculation to quantify this in monetary terms then the loss is 250,000 times, say, $7.5 average for a bottle of wine which equals $1.875 M.  Will I ever see this money back form the cork industry? You tell me… 


The problem becomes even more insidious as most customers do not even realize that the wine has a cork taint. Many times I have had to argue with restaurant staff to explain that wine is spoilt and they haven’t understood a word I was talking about. The upshot is that you might taste a wine that you don’t like and will never buy it again but the problems may have nothing to do with the way the wine was made or stored, it was spoilt due to a faulty closure.


Cork problems have haunted me throughout my carreer. Part of my job is to go out and promote the wines at talks and tastings. I know that I always had to take more bottles with me than needed as I could never be sure that all the bottles would be showing at their best. I always taste every bottle closed with natural cork before every tasting. In a prestigious press tasting in New York some time ago I had to throw away a bottle of Zinfandel ($35 retail) because it was corky. 


The situation is unacceptable, in what other industry is there such a high failure rate, and even more absurdly in what other industry would such a high failure rate be accepted but its consumers?


Alternatives to corks do exist, the most visible being the screw cap, but there are other stoppers such as synthetic corks, glass stoppers, and technical corks. We tried plastic corks for a while and they worked well for short periods of time and are probably suitable for wines which get drunk within a year of bottling, but my experience is that despite our best hopes much wine does not get consumed in that window and the time you discover the problems is when you are in a wine store abroad doing a tasting and the only wine available is something your distributor sold them 6 months ago which the importer bought from you the year before that and you open it and it is already oxidizing. Are you going to explain to the store that the wine is off because of a bad cork? No, usually you try to bluff your way through hoping that the customer can’t see the fault.


So what are the options? Well the answer is not as clear-cut as it seems. Many advocates of alternative closures will swear by screw caps, insisting that they are the best solution for sealing wine bottles. However, screw caps bring with them their own issues. With metal tops tolerance levels for a perfect seal are very tight so if the cap is applied poorly then the seal can be compromised, and the wine will be oxidized. On the flip side the virtually airtight seal offered by a screw cap can lead to reductive qualities in red wines, which will be characterized by burned rubber and bitumen aromas in the wine. 


In the winery we tried synthetic corks, put we found that they led to premature oxidation of the wines. 


We tried twin top corks, a granulated cork body with natural cork discs on the top and bottom of the cork. We discovered that with the batches we were sold that the corks were really difficult to extract, they would often break in half during extraction and that the levels of TCA were not reduced.


We invested in more expensive natural corks where the manufacturer promised that they had a special treatment to prevent TCA. Initially the results were pretty good but as time passed the quality of the corks fell significantly. And that is my experience with cork manufacturers, they will move heaven and earth to try to persuade you that their product is the best on the market and they have proprietary systems in place to remove TCA, they will wine and dine you and pay for you to come and visit them in Portugal. They will ensure that the initial shipment is tip-top, and then slowly they will start to decrease the quality of the corks in subsequent shipments. It is a very simple thing to do, corks come in bags of 1000 pieces so you can easily add some lower standard corks without anyone noticing and increase profitability per bag. I have challenged my suppliers on this point and never really been given a satisfactory answer. You can always request a pre-shipment to check quality but who is going to send rubbish in a bag that they know is going to be highly scrutinized.


Today we have moved to a technical cork called the Diam cork. It is a granulated cork where the cork bits have gone through a process of sublimating carbon-dioxide which removes he TCA in the cork, look at it as decaffeination for corks. Our success rate with this new stopper is very high, we have not needed to re-tool our bottling line as they behave like normal corks, there is no dust and I have not come across a single bottle of wine with any TCA. We now bottle all our wines with the Diam. Someone writing in one of the local wine forums described the cork as a cheap, chip cork, the bright spark wasn’t to know that it was one of the best wine closures you can find on the market today. Using Diam I can confidently open any bottle of wine and know with almost absolute certainty that the wine is just as the winemaker intended. 


It is obvious to me that the future of wine closures is not natural cork, as we know them. It will probably be a combination of screw caps with a diam cork liner or some similar derivative and the wine industry will benefit as a result. You the consumer will begin drinking the wines that we meant to make for you. 


If you feel a need to support the cork industry for ecological reasons then insulate your roofs with cork granules, or buy shoes with cork soles, but don’t put natural cork stoppers in your wine.


Cork top tip! 


If you do come across a bottle of wine that is obviously corky, add a piece of saran wrap to the wine. It will strip the TCA along with some other flavour compounds but will render the wine drinkable.

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