A New Study Settles the Wine Debate on Screw-Caps

By Levi Sumagaysay | January 9, 2020 | Food & Drink

You’re at a fancy restaurant dressed to the nines and expecting an unforgettable experience. You get ready for your wine to be uncorked before you. But there is no corkscrew—your server, instead, twists the cap off that bottle of cabernet.

If that turned you off, you’re not alone.

Diners at Alexander’s Steakhouse sometimes send back bottles when they find out they’re screw-capped, says Sean Widger, the restaurant’s sommelier, who was part of a recent panel discussion with winemakers at the Commonwealth Club in San Francisco.

Cork is “a tradition we grew up with,” says Danielle Cyrot, winemaker at Cade winery (cadewinery.com), who was also on the panel. She acknowledged that some people equate screw caps with the cheap Gallo jug mentality.

But can people really taste the difference? Cade and Napa Valley-based parent company PlumpJack Winery (plumpjackwinery.com), which are among the higher-end wineries that use screw caps, commissioned a study.

Annegret Cantu was the lead UC Davis researcher on the study, which included a blind tasting of sauvignon blanc by 11 panelists who were mostly unable to discern which wines were which.

The findings, presented before the American Society for Enology and Viticulture in 2015, did show some differences among the wines closed with cork, synthetic cork and screw caps. Among the differences noted by the study was in browning of the white wine.

But, “overall, there was no difference by closure,” Cantu says.

Also on the panel was PlumpJack co-owner and General Manager John Conover—with Gordon Getty and Gov. Gavin Newsom. Conover recounted opening an older wine for a special dinner and finding it ruined, aka “corked.”

Cork taint—primarily caused by a chemical compound called trichloroanisole (TCA) that can seep its way into cork or wine barrels, and sometimes causing a moldy smell or flavor in wine—is a persistent problem. In Wine Spectator’s 2016 blind tasting of California wines, it found a 3.27% cork taint rate. It used to be worse: Cyrot says that when PlumpJack decided to use screw caps in the mid-1990s, the cork taint rate for all wine was 10%. “Any other industry,” Conover says, “you’d be out of business.”

Cantu notes that the UC Davis study has similarities to a study published nearly two decades ago in the Australian Journal of Grape and Wine Research, which looked at the effect of different closures on wine. That study found closures had no significant effect on the flavor of wines, but suggested further investigation into what happens to wine when closures are removed from and/or reinserted in wine bottles.

Jean-Noel Fourmeaux, winemaker for VGS Chateau Potelle (vgschateaupotelle.com) in St. Helena, was on the panel too. He wanted everyone to know that, even if people may think the French are traditional, “what we want is wine to be the best.”

He called screw caps a “genius marketing coup” that he has nothing against. “I have no religion,” he says.

But Fourmeaux also said it’s too early to tell whether screw caps can consistently lead to high-quality aged wine. A knock against screw caps is that they can be so airtight that they don’t allow enough oxygen into a bottle, causing reductive notes that could be unpleasant, such as rotten cabbage.

That’s something that PlumpJack is planning to continue to study. “We want to see how it ages out,” Conover says.

Another French winemaker—who was not part of the panel, but who shared his thoughts about cork versus screw caps—is more of a traditionalist. Olivier Humbrecht’s family has made wine since the 17th century. It’s in his blood.

“Cork gives complexity,” he says, adding that it’s simply “sexier.” He also says it’s better for the environment, a common argument made by proponents of cork: that we need the trees that produce the bark from which cork comes because we need oxygen.

Cyrot counters that, because of all the work that goes into harvesting, processing and bottling wine that could later go bad, cork closures aren’t necessarily greener.

“I’d argue that negates environmental positives you get with cork,” she says. She pointed out that metal screw caps and tin liners can be recycled.

The cork industry is working on reducing cork taint, including by changing processes and no longer allowing the use of chlorine for sanitation. There is also new technology to detect TCA.

At the blind tasting for the Commonwealth Club members who listened to the discussion, two people were able to tell the difference between the wines that used different closures, while two people couldn’t. I did my own blind tasting of the Cade 2012 cabernet with screw cap and cork, and found I was able to distinguish between the bottles with the different closures. But it’s possible it was just a lucky guess.

“The only thing that counts is your taste,” Fourmeaux says. “It’s not that wine should have a score of 98. It should be about your mood. Enjoy it.”

Tags: wine

Photography by: courtesy of brand