Wine study seeks to bring closure to cork vs. screw cap debate

09/20/2012 12:54:00 PM
Vicky Boyd

A debate over the best closures for wine bottles—cork or screw cap—has raged ever since winemakers began putting screw caps on higher-end wines.

Now researchers at the University of California, Davis, are using science to answer the question once and for all, according to a news release.

They want to find out whether consumers can taste a difference in wines that were bottled and capped at exactly the same time with the same wine. The only difference will be the closure.

The researchers are evaluating 600 bottles of sauvignon blanc closed with either a natural cork, synthetic cork or screw cap.

The study will monitor chemical changes in the wine during aging, culminating with a sensory evaluation by wine experts and consumers during summer 2013.

The researchers want to determine whether the tasters can detect subtle differences in oxidation levels that occur during aging.

The researchers have even gone so far as to enlist the help of John Boone, a radiology professor, to obtain CT images of the 200 natural and synthetic corks.

They will use the images to analyze differences in the corks' internal structures.

"Our goal in this study is to determine if individual bottles might be getting a lot more or less oxygen—and therefore aging at different rates—as a result of the variation in the closures used to seal the bottle," Andrew Waterhouse, an enology and viticulture professor, said in the release.

He is conducting the study with undergraduate student Jillian Guernsey.

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Rupert Knowles    
Cranfield, Beds, UK  |  September, 27, 2012 at 01:18 PM

Wines are being consumed younger and younger. For such everyday wines, I am sure the closure makes no difference, but are these researchers testing wines laid down for 10 - 20 years? Second point, corks are a major export from Portugal. The Portuguese economy is in dire straits, and the least we can do is follow tradition and put a proper cork in a good bottle of wine. Third point, the cork oak forests are an important environmental asset on the Atlantic coast and if cork is no longer required by the wine industry, the forests will no longer pay for themselves. So for goodness sake pay up the extra pence for a proper cork! It may or may not be good for the wine, but it is certainly good for the economy and environment of Portugal.

Hank Kornfeld    
NY, USA  |  October, 16, 2012 at 11:21 AM

Dear Mr. Knowles: With all due respect, I do not think you have any idea what you are talking about. I am a graduate student in a Masters of Food Science program. I am studying cork vs. screwcaps from the point of view of packaging, and how well the seal of one closure compares to another. There is a great myth which you seem anxious to perpetuate about the environmental advantage of cork "forests". Prior to the Portugese revolution in the 1970-80's, cork was a family-run business controlled by generations of the same families who did only the most basic clearing of the areas around cork oaks and allowed the trees and the cork bark to mature at a leisurely and sustainable pace. After efforts during the revolution to nationalize the cork industry, a few multi-national corporations, owned and run by multi-billionaires took over the industry and have virtually destroyed it. They have sprayed anti-fungals and anti-herbicides around the trees to keep from having to weed these areas by hand. They have "cleaned" corks by soaking them in clorine bleach to artificially whiten their color. The have begun harvesting the trees much more rapidly than the long-accepted every 12-15 years, sometimes harvesting as little as 9 years after the last harvest. Individuals who neither know nor care about the longevity of cork trees are now in charge. They are more interested in making a quick profit, at any cost to the trees, the cork industry or the wines the corks are supposed to properly seal. Two suggested sources for you to consider reading: Wine Bottle Closures by Jamie Goode and To Cork or Not to Cork by George M. Taber. I'm interested in your comments..Hank Kornfeld

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