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Seeking Closure

Which wine closure system do you think will dominate the wine industry?

Do you like natural cork or do you think screwcaps are the way to go? What is your opinion on synthetic cork? If you are like me, you've had this discussion many times.

The issue of closure is not as simple as you may think.

With a variety of options for closing a bottle of wine, it is natural to have biased opinions about which technology is best. This is no simple topic to discuss. Much chemistry is involved and I'm no chemist. We'll take a look at the type of closures currently in use and I'll express some biased opinions about them.

Real Cork: We're talking oak cork here, fresh, woody, clean, renewable, wonderful cork. Natural cork is the traditional method for closing a bottle of wine. It protects and seals and even allows some air and moisture to pass. Natural cork is something I've grown fond of. I enjoy the ritual of opening a bottle of wine, especially when I have spectators:

1. Remove the foil, 2. insert the screw, 3. turn, turn, turn, 4. leverage out the cork - "pop", 5. smell the cork, 6. pour a little wine, 7. swirl it in the glass, 8. smell the wine and finally 9. taste the wine... yummy and fun.

The ritual of opening wine is only ruined by the occasional unexpected sacrifice. If the cork is "bad" then the wine is sacrificed and the fun is gone. If there is one thing I've learned about wine, it is how to spot a bad cork. A "corked" bottle of wine is due to the presence of 2,4,6 trichloroanisole (TCA) in the cork. This will negatively affect the taste of the wine. How bad the wine will taste depends on the concentration of TCA. It does not take much to ruin a bottle for me. Don't tell me the wine is supposed to taste musty, with hints of wet cardboard. That my friend is a corked bottle of wine (yes, I'm a bit of a cork snob).

How frequent is the occasional bad cork? I've seen statistics ranging from a high of 15% bad to a low of 1% bad per lot. Either way, a "corked" bottle = a bad experience. This has encouraged the industry to look at other closure options.

Synthetic Cork: If cork works so well, and has worked well for centuries, then synthetic cork should be a good replacement. Synthetic cork looks like real cork, but is composed of synthetic materials. Switching to synthetic cork also allows a winery to keep their investment in their bottling equipment - no retrofitting.

One issue with synthetic cork is the concern about long-term contact with wine and the possibility of the cork breaking down in the bottle - ugh, that would be nasty plastic taint. Another issue is about recycling the synthetic cork. Synthetic cork is not bio-degradable and should be separated into the recyclable bin. Some manufacturers are embracing new materials and claim Organoleptic neutrality. Visit to learn more.

Screwcaps: Industry reaction to bad cork is also evident by the use of screwcaps on bottles of wine. The Australians embraced box-wine technology early on and made it main-stream, and now have accepted a variety of modern closure technologies like screwcaps. The Australians even trialed screwcaps in the 1970's. By the late 1990's screwcaps became common and are now guest approved. They also provide an excellent, quality seal - even though they ruin the "ritual" of opening wine. Wine sealed with screw-caps should be as good as the winemaker intended. And no risk of cork taint. If the wine is meant for long term storage, a different size seal can be inserted by the winemaker to allow for better oxygen transmission rate (OTR).

As good as screwcaps are, some technical issues have emerged, post-bottling. A sealed bottle, is a sealed bottle. This can create sulfur chemistry known as "reduction". Any studio potter out there know that a "reduction" atmosphere is one without oxygen. According to Jamie Goode, Wines & Vines, August 2007, page 24, "...wines closed with tin-saran screwtops may show mercaptan odors, while saranex screwtops are not implicated." The issue is complex, and seems to affect wine which is intended for longer term storage. Once again, recycling is of issue with screwcaps. Check with your local recycling facility for the best method of recycling your screwcaps. And drink wines sealed with screwcaps sooner than later.

Zork: One of the newer closure technologies embraced in Austrailia is called a "Zork" and is now manufactured in the United States. According to the manufacturer, it provides the convenience of a screw-cap and the pop of a cork. The manufacturer also states that it provides consistent and predictable oxygen transmission rate (OTR). visit to learn more. I've not personally opened a Zorked bottle yet.

Going Green: Is there a "Green Solution" to our cork dilemma? The truth is, natural cork is a renewable product. In Europe there are entire forests of "cork" trees. According to the World Wildlife Federation, the Andalusian forests of Spain store some 151 million tons of C02, of which cork trees account for 10%. A harvested cork tree absorbs 3-5 times more than one which is not harvested. Cork oak forests cover about 11,600 square miles of land in Portugal, Spain, Algeria, Morocco, Italy, Tunisia and France. They support a high level of biodiversity including some endangered species. If the cork industry fails, the cork oaks will be abandoned and the land will become fair game for grazing and development (this would be a negative folks).

Cork supply companies have devoted millions to research cork taint. The results should be fewer bad corks. One French cork supplier claims to have eliminated TCA entirely, while others say they have reduced it to under 1%. The quality of the cork will vary by the supplier and by the winemakers choice in purchasing. Cost is always of issue to any business.

Advice: Do I offer any advice? Of course I do, it's free.

1. Natural cork is my favorite closure. It presents well (love the ritual), if it is a good cork then it smells like a good cork. Natural cork is still the best closure for cellaring those most prized and most expensive, bottles of glorious wine. Technologies such as "irradiation" may be of benefit for reducing or eliminating TCA in cork. And natural cork is good for the environment. So feel good about opening that bottle of wine.

2. Synthetic cork is a good choice for wines to be consumed within three years. This would include most white wines, roses and young reds. The future looks good for synthetic cork as the technology continues to evolve and as more tests are performed. Recycling remains of issue.

3. Screwcap/Zork closures are far cheaper than cork and provide the greatest cost savings for the large production wineries. Screwcaps are more accepted today by consumers, but still lack a quality feel. Screwcaps are possibly best for the younger wines too, white, rose and young reds. The issue of "reduction" and sulfur chemistry remains an issue to be resolved by the industry. Recycling also remains an issue.

4. One of the newer closures I've seen are "glass corks". Glass corks are made of glass. While not widely used, glass corks present well, provide a good seal, have a pleasant "pop" at opening and have a nice feel/weight to them. Customers might tend to collect them and show off to friends. It remains to be seen if other issues evolve around this type of closure.

A wide variety of closure options prove that we have a healthy, active industry. The fact that people are concerned is also a positive sign. Social and environmental issues have taken these discussions further and may affect your personal choice in purchasing wine. At least you are little bit more informed. Go and research on your own.


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