Why Some Winemakers Don’t Just Put a Cork In It

In New Zealand, virtually every wine in the country is bottled under screwcap, while in Spain, cork is mandated. Bottle closures can be real corks, synthetic corks, screwcaps, glass stoppers—but is one better than the others?

… A FEW WEEKS AGO I was sitting on a suburban commuter train bound for New York when a group of men who looked to be in their late 30s entered the car. They were talking about the best place to find a cheap drink close to Penn Station. After settling on a Chinese restaurant where “a big glass of whiskey” cost $5, the discussion shifted to wine. One of the three men remarked that he’d joined a wine club but was worried when the bottles arrived and were all closed with screw caps. “I thought ‘Uh-oh,’ ” he said. One of his friends replied “Uh-oh,” signaling that they both thought screw caps meant something bad.

I was surprised by this exchange. Wines bottled with screw caps have become so commonplace that I assumed everyone thought they were just as good as wines closed with corks.

I don’t have a closure preference or prejudice. Over the years, I have had problems with corks, from leakage to cork taint, as anyone who drinks wine probably will at some point. Conversely, I’ve had some positive experiences with screw caps. For example, I’ve found that, once opened, a bottle of wine with a screw cap seems to stay fresh longer than one with a cork.

Wall Street Journal photo
Wall Street Journal photo

ILLUSTRATION: SERGE BLOCH

In a completely unscientific experiment, I once saved several half-empty bottles and stored them in my fridge for a few days. Each had a different closure: a real cork, a synthetic one and a screw cap. I tasted the wines over several days and found that the screw-capped bottle tasted brighter and more lively than either one of the cork-closed bottles, both of which tasted tired or, in wine parlance, “more advanced.”

Why did the screw-cap wine do so well? I recently asked James Healy, winemaker at Dog Point Vineyard in Marlborough, New Zealand, whose Sauvignon Blanc was the winner of my ersatz trial. Mr. Healy credited the fact that the fruit had been handpicked, pointing out that handpicked fruit is “less oxidizable.” He also noted that there is very little oxygen ingress with a screw cap versus the porous cork. To Mr. Healy, screw caps are “the most reliable stopper for wine,” whereas when it comes to cork there are “good bottles” and “bad bottles” depending on the quality of a cork.

And yet he is one of a small number of Kiwi winemakers who uses both cork and screw caps; at least 90% of New Zealand wines are closed with screw caps. Why does he use cork at all? Mr. Healy explained that he thought the wine developed well under cork—but that he also kept it in the mix because he was “old-fashioned.”

New Zealanders, who popularized the use of screw caps with their Screw Cap Initiative in 2001 (an intensive research-paper-cum-manifesto), are the leading proponents of screw caps. While the closure has since gained favor among winemakers from all over the world, especially in Australia, screw caps represent only about 15% of all closures, according to a recent Nielsen report. About 70% of all wines are still closed by corks. The rest of the market includes synthetic, plastics-based corks (just under 15%) and glass stoppers (although their share of the market is tiny). Exact figures are impossible to establish as the precise number of bottles of wine produced every year is unknown.

Cork is certainly the closure with the clout of history and tradition. It’s been used for centuries, and virtually every wine professional I spoke with invoked one or both of those words when describing his allegiance to cork. Aldo Sohm, wine director of Le Bernardin and partner at the Aldo Sohm Wine Bar in Manhattan, said that “as a traditionalist” he preferred it to other alternatives. It seems to be the choice of winemakers, too; a 2015 survey of wine producers in Wine Business Monthly found cork was the favorite by far.

Of course, cork has had many problems over the years—problems that have inspired the search for alternative closures. These flaws include the aforementioned leakage and cork taint, when the cork is infected by TCA, or 2,4,6-trichloroanisole, a compound that lends an off-putting aroma to wine. But according to Carlo de Jesus, communications director at the Portugal-based Amorin, the world’s largest cork producer, corks have improved in recent years. “We’ve spent €200 million [$223 million] in the last 12 years [on] changing procedures, research and development. We changed everything except the product itself,” he said. One of the innovations, “steam distilling” corks, was designed to prevent and cure TCA, according to Mr. de Jesus.

Peter Bell, winemaker of Fox Run Vineyards in New York’s Finger Lakes region, returned to cork in 2013 after more than a decade of using synthetic, citing leakage and an occasional “rubbery” smell. Mr. Bell said he wishes he could use screw caps but retrofitting his bottling line would cost as much as $50,000.

When I mentioned the rubber smell to Malcolm Thompson, vice president of strategy and innovation at Nomacorc, the world’s largest producer of synthetic corks, he took issue with the idea. Mr. Thompson said the North Carolina-based company has scientists perform constant analysis to ensure their corks are free of such flaws. (For the record, Mr. Bell wasn’t referencing Nomacorc.)

Will a screw cap ever equal—or replace—a cork for wine drinkers and winemakers outside of Australia or New Zealand?

Nomacorc recently introduced a new group of corks, Select Bio, made of sugar cane—which, as Mr. Thompson noted, means they aren’t actually synthetic at all. The corks are guaranteed to be invulnerable to cork taint and oxidation for 15 years, and can even be matched to a wine’s aging profile using the company’s computer model. For example, a wine that should be consumed within a few years would be fitted with a different Nomacorc cork than one meant to age a decade or so.

When the team at PlumpJack Winery in Napa was experimenting with closures for their 1997 Estate Cabernet they considered synthetic corks before deciding to release two versions of the $125 wine under screw cap and real cork, said John Conover, the winery’s general manager. While this might seem unremarkable today with so many screw-cap wines on the market, it created such a stir in 2000 that when the wine was released Robert Mondavi said, “Better you than me,” Mr. Conover recalled.

The PlumpJack team donated 20 cases of each wine to the Department of Viticulture & Enology at the University of California, Davis, so researchers could study how the wines aged. (Aging is the most common reason winemakers and collectors say they prefer corks, as there is long history of wines that have aged well under corks.) The PlumpJack team consults with UC Davis each year to see how its wine is faring, measuring the color change, oxygen transfer rate, etc.

The latest findings show that the screw-capped wines were more consistent in flavor and aged more slowly than bottles closed with cork, which aged not only more rapidly but more variously, too. PlumpJack, which still produces its PlumpJack Reserve Cabernet under both closures, now also bottles the Sauvignon Blancs and Cabernet Sauvignons from its second label, CADE, under screw cap, due to demand from collectors who “don’t like the Russian roulette of corks,” according to Mr. Conover.

Of course many collectors, like my friend Jeff, still prefer corks. Though Jeff has “no problem” with white wines or light reds with screw caps, for wines that are meant to age, it’s another story. “I just believe wines age best with corks,” he said, adding that he couldn’t imagine opening a great bottle of Burgundy by twisting off a cap.

Larry Schaffer at Tercero Wines in Los Olivos, Calif., regards that belief—“If you’re putting a wine under screw cap, it must not be a wine meant for aging,” as he puts it—as the single greatest misconception about screw caps. Mr. Schaffer bottles all of his wines, red and white, under screw cap.

Will a screw cap ever equal—or replace—a cork for wine drinkers and winemakers outside of Australia or New Zealand? Will corks ever be completely free of taint, or will synthetics be widely considered as good as the real thing? Much technical progress has been made over the past decade with each form of closure, but wine is a beverage of tradition, history and, above all, perception, as I discovered with that group of men on the train.

Email Lettie at wine@wsj.com
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