The purpose of a wine closure is to keep the wine in and the air out. When a winemaker decides on a closure s/he considers many elements including, regulations, tradition, style of the wine, cost, and consumer perception. Cork has been the favorite wine closure for hundreds of years, but other options exist and studies have been conducted throughout the world, trying to pinpoint the one that is best.
Here are just a few options with their benefits and their peccadillo’s.
Corks have been used to seal wine since the seventeenth century when Champagne maker, Dom Perignon used them. Cork is a natural, flexible material that seals well and lends an air of tradition and sophistication to a bottle of wine. But due to the extensive demand for cork, another viable closure would help to easy the demand on the cork oak tree.
While cork has been an easy closure to work with and does a relative fine job of sealing wine, there are some problems. The main one is cork taint. This happens when TCA (2,4,6-trichloroanisole) contaminates the cork. The result is a mold that grows on the bottom of the cork and leaches out into the bottled wine. Cork taint gives a musty smell, and a ‘wet-dog’ or moldy taste to the wine. This is referred to as a “corked” bottle. Research indicates that between 5 to 10% of all bottled wines spoil due to cork taint.
A major advantage of the cork closure is that it is porous and lets some oxygen interact with the wine. This allows for better aging by letting the wine develop secondary characteristics like new aromas and flavors. This is especially desired with reds that are to be cellared for years.
Synthetic corks are made from high-grade polymer plastics. While it is a suitable alternative for natural cork for the short term, synthetic cork has not fared well in keeping oxygen out for longer periods of time. Since it does not retain its seal over the years, it is suggested synthetic corks be used on wines that will be consumed within five years of bottling.
Synthetic corks are used in less than 10% of all commercially bottled wines in the world. In Italy, synthetic corks are used mainly for white wines. Natural corks are used for red wines and the more paramount wines that require aging.
Overall, consumers have grudgingly accepted them. While they do not crumble or break apart in the bottle, synthetic corks do not provide any clues about the wine such as freshness or aroma. They do, however, provide the required “pop’ when pulled!
At the beginning of 2000, winemakers from Australia and New Zealand decided to end their problems with cork taint by using screw caps on their wines. In 2001, 1% of New Zealand wineries were using screw caps. By 2004 it had risen to 70%. Australia followed suit and now the majority of non-sparkling wines in Australia use screw caps. Even the United Kingdom is learning to embrace them. In 2003, 41% of consumers viewed a screw cap wine as acceptable; that number is up to 85% as of 2011. (Just over 10% of Americans find a screw cap to be acceptable on wine.)
Some advantages to screw caps include easy of use and no tools required. Other countries (Spain, Italy and France) are also reconsidering the screw cap for wines that are to be consumed while young. A screw cap also helps a wine retain its fruitiness, freshness, and aroma. For wines that are to be consumed within 3 to 5 years, screw caps are fine.
But for wines that are to be aged, screw caps are not the answer. Since they do not allow any air into the wine, which aging reds need, that can reduce certain sought-after qualities. And, that ritual “pop” of the cork is missing.
There are two other alternative wine closures that are being used in the market.
The glass/plastic closure is known as Vino-Seal or Vino-Lok. The stopper has an inert o-ring that creates an airtight seal, thus preventing oxygen from getting to the wine.
The glass closure was introduced into the European market in 2003 and has been used by over 300 wineries. While easy to use and attractive, there are some drawbacks for use in the U.S.
Unfortunately, compatible bottling equipment is only found in Europe, so to use it in the U.S. would require hand bottling, or a major investment in new bottling equipment and shipping it over here. Also, one topper cost 70¢ - a tremendous expense compared to other closures.
Zork is the newest wine closure on the field. Launched in 2010 in Australia and New Zealand, the closure is made from 100% recyclable food-grade polymers. The closure is similar to a screw cap expect that it “pops” when opened.
To open, you pull the tear tab at the bottom and unwind to the T-top. Once opened, the closure becomes the T-top with its reusable cork.
New research, the “Bottle Aging – Closure and Variability Study,” is now being conducted by the University of California, Davis, in partnership with the PlumpJack Group. The study, which was announced in June, will compare the effectiveness of natural cork, synthetic cork, and screw caps on keeping a wine at its utmost quality.
Two hundred bottles of Cade Napa Valley Sauvignon Blanc, crafted by a winery owned by the PlumpJack Group, will be used in the study. The study will establish what the range of differences is for each closure. Findings are expected to be published at the end of 2013.
For alternative wine closures to really catch on, they will have to first gain the trust of winemakers and producers. These are the people who know and understand wine science, and want to use the best closure available for each of their wines. That may mean that a winery or producer might use two or three closures; each wine topped with the best closure suited for it.
Considering that most wines bottled today are meant to be consumed within three to five years, screw caps may make sense to many wineries and producers, especially those targeting a younger wine drinking crowd who are more versatile and more accepting of change.
Then there are those of us who love the tradition, the romance, and that exciting sound when you pull out the cork – the “pop” that just says “Relax and Enjoy!”