Just screw it: Why winemakers ditched cork for caps

When he founded the Blended Learning winemaking course three years ago, Thomas Henick-Kling had an important choice to make: How to seal his department’s student-created wines.

“For me, there was no question,” said Henick-Kling, director of Washington State University’s Viticulture and Enology program. “We were going to put them under screw caps.”

Traditional cork, with its iconic pop, lost out to the humble aluminum cap — and for good reasons.

“It’s the best technology for closing wine in a glass bottle,” said Henick-Kling, who is out to dispel old myths about caps being an inferior product typically used for cheap wine. He chose caps to avoid a common problem called cork taint.

“I’m a rationalist,” said Henick-Kling, explaining his decision. “It makes sense.”

‘Corky’ concern

For the past six years, every wine made by a WSU student or researcher has gone under screw cap.

We’re not interested in dealing with cork-tainted wines,” said Jim Harbertson, WSU associate professor of enology.

Cork taint can wreck as many as seven bottles of wine out of a hundred. Tainted wines may have a moldy, musty, off-putting smell, or hardly any smell at all — either way, your sipping experience is ruined.

Cork taint is mainly caused by two compounds, trichloroanisole and tribromoanisole, known as TCA and TBA. They develop anywhere that wood, water, chlorine and microorganisms combine. Even store-bought fruit can be ‘corky,’ says Henick-Kling, if it’s transported on pallets that happen to get splashed by chlorinated water.

“Dump chlorinated water onto wood or cardboard, and boom, you have TCA,” said Henick-Kling. “You only need parts per trillion, tiny amounts,” for the chemical to be detectable.

In the Blended Learning program, enology students learn how to make and market their own wines over the course of a year, developing their product to commercial standards in partnership with Washington wineries. Blended Learning produces a small run.

“200 cases is a lot for us,” said Henick-Kling. Yet even in a limited run, “I save, because I don’t have to accept a failure rate of two to seven percent, or in some cases even higher.”

Inconsistency in natural corks would be a big problem in the small number of bottles the university produces for research, said Harbertson.

“We cannot simply discard several and look for one with a good closure,” he added. “Every bottle needs to reflect the quality of wine produced for a particular research project.”

Bigger wineries have made the same switch to caps for the same reason.

“If a consumer opens their wine, and it happens to be corky and they don’t like it, they may not know it’s the cork. They blame the winery,” said Henick-Kling.

Breathe in, breathe out

Since wines started flowing into glass bottles in the 15th century, corks, made from the bark of the cork oak tree, have been the main stopper. Today, about 80 percent of the world’s 20 billion bottles produced annually are sealed with cork.

Cork is spongy enough to be forced into the neck of a wine bottle, but expands to form a seal. Cork quality can vary, however, and wines can breathe or age differently depending on cork variability.

“A perfect cork doesn’t let in air,” said Henick-Kling. A bad cork will quickly oxidize wine. The problem, he said, is there is no practical way to test every cork, so winemakers always run a risk of a corky or poorly aged wine.

Under caps, “you can control oxidation. You can completely keep it out, or allow a small, controlled amount of oxygen to get in,” Henick-Kling added. Airflow through a cap is controlled by the kind of plastic liner that forms the seal. Some liners breathe, others don’t. “With a screw cap, I don’t have to worry. It’ll be fine for 20 years or longer.”

Pros and cons

Researchers are studying how wine – and consumers – react to different closures.

“There is interest in the industry to see how these wines change,” said WSU food scientist Carolyn Ross. A 2007 study by scientists with the Australian Wine Research Institute looked at changes in wine properties during two years of storage under cork and caps.

“The chemical reactions that occur in the wine vary with the closure, due to the different amount of oxygen that is present,” she said. Under caps, Australian researchers found in some wines reduced aromas — unwanted sulfur compounds smelling subtly of rubber, mocha or struck flint. Reduced aromas can also develop under corks. It takes time for these aromas to develop.

“A lot of people drink their wine before they see change,” Ross said.

A 2007 study at Oregon State University looked at how different closures affect consumers’ purchase intent and price expectation. The study found consumers are willing to pay less for caps. Ross suspects the situation may have changed since then.

“People are understanding it more,” she said. “They’re exposed to more screwcaps now, on higher quality wines. People who are really experienced with wines may have already worked through that.”

Aesthetically, caps and corks are different. Screw caps twist off. It requires some finesse with a corkscrew to open, but the satisfying pop when the cork comes free is a traditional sound of celebration.

“There’s a certain, satisfying sound, and a certain feel, when you’re removing the cork,” said Harbertson. “I would miss that.

“But I don’t want the hassle of cork taint,” he added. “Most of us would prefer not to deal with it.”

The material in this press release comes from the originating research organization. Content may be edited for style and length. Want more? Sign up for our daily email.

6 thoughts on “Just screw it: Why winemakers ditched cork for caps”

  1. Depends on what the screwcap liner is made of, and how would a consumer know? Saranex liners are common and the most oxygen tight seal. Saranex as in Saran wrap is not used in Saran wrap anymore as acid containing substances (such as cheese) leach plasticizers in to the cheese. Wine is more acidic and has alcohol a wonderful solvent, so a Saranex liner is not a good thing unless the wine is kept upright all the time as is the case normally in a beer bottle. Polyethylene liners are fine but leak way too much oxygen, but I believe someone makes one with a metal liner that likely would help a lot. I usually avoid screwcaps unless very young white wine and found upright on shelves.

  2. For myself a screw cap would in any case work out more effective and economic. I always buy bottled wine and drink one glass per day. The screw cap can go back on the bottle and seal it again. The traditional cork cap can never go back into a half used bottle as it would not fit again or it has in any case been torn apart by the cork screw.

  3. NO NO NO !! A cork cap definitely influences the aroma and taste of the wine as well as the whole atmosphere around serving the wine. I also intend to believe that higher quality and more expensive wines will never settle for ordinary screw caps, just the same as the fact that they would not sell their products in cheap wine containers such as boxes. Rather bring back the cork cap and cork screw.

  4. The cork cap might have been a traditional method to seal wine in bottles, but I agree that screw caps are by far the best and easier to use. My father has a wine rack in his bar at home in which especially red wines have to lei down to age to perfection. I found that after a few years the bottles with the cork caps start to leak through the cork. I’m sure this will not happen if scientifically tested screw caps are used. I also like the pop sound when a cork cap is removed, but I agree with MainFragger that surely something can be invented to still make the pop sound. Goodbye cork screw!

  5. I love my wine and don’t mind a screw cap. It is much easier to open and one doesn’t have to worry about forgetting a cork screw at home when going on eg. a vacation.

  6. Put a pop top that releases with the release of pressure when the bottle is closed that makes a popping noise to simulate the cork being removed..

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