Sealed with a Cork or a Screw Cap: What Makes Better Wine?

How do you like your wine contained? Does the container affect your enjoyment of the wine itself? For the most part, it comes down to how wines are sealed. While there is a difference between quality of true and artificial corks, there is also a difference in perception between the two. 

There are a few choices for winemakers when it comes to containing wine. With a bottle, they can use a screw cap or the traditional method of inserting a cork. The cork can be made of true cork or from porous plastic. Alternatively, they can use a can, or plastic bladder in a box. 

Wine is typically bottled in 750mL bottles and closed with a cork. Does it work? Yes, but there is a problem. Sometimes corks don't last as long as the wine, and when the cork goes bad, the wine goes with it. A cork can cause wine faults of oxidation and corked taint. When the waiter brings you wine, he pours a small amount in your glass for you determine whether the wine is "corked," which can happen in about in about 5 percent of bottles.

Wine corks have been used to seal wine bottles for centuries. There is an argument that a small introduction of oxygen plays an important role in the aging of wine. While others argue that this amount is almost zero in a sound cork and that any introduced oxygen is harmful. I suspect that the truth of this oxygenation issue lies somewhere between zero and a minute amount of oxygen getting in to help age the wine. 

Screw caps have a much lower failure rate than corks, and they are easier to open. Screw caps typically have a PVDC, cork, or rubber seal used to seal the bottle. Screw caps and artificial corks are gaining increasing support as an alternative to cork for sealing wine bottles. In New Zealand and Australia, screw caps have overtaken cork to become the most common means of sealing wine bottles, used by nearly 70% of winemakers. This closure has not been easily adopted, however.

When the screw cap was introduced in Australia, people did not buy the wine with the screw top because they were often associated with cheap wine. Use of the screw cap in Australia was discontinued for about two years before reintroduction, with half of the Australian wineries using the aluminum screw top. Some of the premium American winemakers like Robert Mondavi with his premium wine Opus One have put the screw cap on about half of his bottles, and the screw top bottles outsold the cork. Other American winemakers that have taken the screw cap are Bonney Doon and Plumpjack.

Plastic artificial corks have proven to be a reliable seal and are porous enough to allow a small amount of oxygen to pass through the cork. This should satisfy anyone who strongly believes that a small amount of oxygen is beneficial to the aging of wine. This cork, like the traditional cork is not always easy to open, some times harder.

Screw caps also eliminate contamination from TCA (trichloroanisole) a chemical produced by a microbe inside of a cork. It is so pungent that it only takes five parts out of one trillion to be detectable to your taste.  

Wines packaged in a box or cans have not been heavily researched for me to be able to give a reliable comparison at this time but theoretically, they seem a good alternative to using a traditional cork and bottle. Once you can get past the stigma of those methods previously having been used for cheaper products.

In regards to ease of opening-the screw cap, aluminum can, and box wine prove far easier than either the traditional or artificial corks. Corks present a potential crumbling problem, not to mention the "user error" or opening a corked bottle wrong. And the potential mess from dropping a bagged and boxed wine is much less than that of dropping a glass bottle. 

And while neither a cork nor screw cap can actually make a wine better, a cork can definitely make a wine worse. It looks at this moment in time the screw cap is a big winner, by far.

Jim St. Germain

Jim St. Germain is president of St. Germain Cellars and the resident hops enthusiast. When he isn't evangelizing IPAs (75+ IBUs!), he enjoys a nice glass of pinot noir or good whiskey, neat.