Don't Just Put a Cork in It
An Introduction to Different Wine Closures
There was once a time when a wine sealed with anything other than a cork was a
clear signal to serious wine lovers of a lower-priced, lower-quality bottle of vino.
Thankfully for those of us who have been tempted to introduce a particularly stubborn
cork to the business end of a firearm, the days of guessing a wine’s quality based on
its closure are long behind us.
The perception of cork alternatives, such as screw-caps, is still lagging a bit
behind their reality. Some of the wine world’s most exclusive (and priciest) wines
are now sealed with alternatives to natural cork, with some high-end producers
converting their entire product lines to technical corks, screw caps, glass stoppers,
or synthetic corks – and making no bones about telling the wine market of their decision
to do so. The technology behind these alternative closures have made the market much more
competitive, to the point that traditional natural cork producers have also had to
significantly up their quality game (along with their marketing efforts).
While it’s generally a bad idea to judge a wine by its closure, a little knowledge
goes a long way in the wine-shopping experience, and it helps to know the benefits and
the drawbacks of how your favorite wines are topped off. To help you make sense of all
these alternatives (okay, and to help you sound more impressive at your next wine get-together),
here’s the run-down on the most common wine closures and what makes them appealing to wine
producers and wine lovers alike.
Made from the bark of the Quercus suber oak (mostly grown in Portugal), cork has
been used since at least ancient Egyptian times to seal vessels containing food and
liquids meant to be preserved or transported. Cork is pliable, elegant, sturdy, and
renewable, and we have hundreds of years worth of examples showing how well it can
age a fine wine over many decades. But cork’s most appealing asset – that it’s a
natural resource – is also its biggest drawback. Temperature and humidity changes
can expand or contract cork, which can lead to premature aging of wine in the bottle.
Cork is also susceptible to trichloroanisole (TCA), bacteria that can ruin a wine,
dulling its flavors and giving it unpleasant off-odors (commonly known as cork taint).
Finally, cork is unique in that it’s one of the few products that requires a specialized
tool – a corkscrew – to extract it.
In an effort to keep the benefits of cork while reducing that dreaded cork taint,
companies like DIAM began making agglomerated corks that are specially treated to all
but eliminate TCA bacteria. The result is a highly sturdy cork alternative that has many
of the same benefits of natural cork, with far less cork taint and often less potential
leakage. While there is less of an aging track record than with untreated cork, the risk
is low given that it’s made of the same material. Of course, technical corks still require
wrestling with a corkscrew when you want to get a bottle open.
What if we could get the benefits of cork – the traditional corkscrew opening and
oxygen transfer for slowly aging fine wines – without leakage and cork taint? That’s
the driving force behind synthetic corks, which are usually made from synthesized plastic
compounds. These corks are recyclable, they are often easier to extract from a bottle than
traditional cork, and they usually offer very specific oxygen-transfer rates, so they can
be matched to how long the wine they are closing is expected to age in the bottle. Some
producers, such as Nomacorc, are now offering zero-carbon-footprint corks derived from
sugar cane biopolymers. The downside, apart from still requiring a corkscrew, is that
we don’t yet have a lot of examples of fine wines aged for long periods under these
relatively new closures.
In the 1970s, some forward-thinking Australian wine producers who were getting frustrated
by the issues inherent in using natural cork began experimenting with closing their wines via
screw caps. These closures consist of a metal cap with an internal liner that attaches to a
metal “skirt” around the neck of the bottle. The perforation along the cap’s bottom edge
allows the screw cap to be removed without the need of a corkscrew (or any other tool),
although the best results are usually achieved by holding the cap and twisting the skirt
rather than twisting the cap as one might when opening beer or soft drinks. Screw caps
are almost totally immune to TCA infection, they handle temperature and humidity variations
well, and they can be reused to temporarily store unconsumed wine while still in the bottle.
They also don’t require bottles to be stored horizontally, which is necessary for keeping
natural corks moist, and we have many examples of wines aging gracefully for long periods
under screw caps. They can still leak if damaged, however.
Though not widely used in the United States, glass-stopper wine closures are popular in
some areas of Europe, particularly Germany and Austria. With this closure, a glass (or
sometimes plastic) plug with a flat top is used to close the wine bottle. An inert “O-ring”
seal sits between the stopper and the bottle’s neck, creating an airtight seal that prevents
TCA contamination and significantly limits oxidation (the exposure of wine to too much air,
which can age it prematurely). Glass is, of course, recyclable, and the glass stoppers have an
elegant look. They are also very handy for re-sealing a bottle of unconsumed wine so it can be
kept for a few extra days after opening. The main drawbacks are that glass stoppers are heavy,
adding additional weight to the wine bottle for shipping, and they are expensive for producers
to use (which could mean a more expensive price tag for you ).
At the end of the day, always remember to choose a wine based on personal preference! Regardless
of how it's corked, if you enjoy what's inside, drink up!