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Too Closed to Call?

Martin Gillam - March 2008

When it comes to bottlenecks, it seems that there are as many stoppers as there are opinions. Martin Gillam revisits the ongoing wrangle over corks and their alternatives.

Physically, the battleground could be hardly more narrow: the neck of a wine bottle.

But commercially it's a battle being fought on rapidly escalating fronts, as rival manufacturers campaign to plant their flags—or more accurately their patented closures—into the necks of the 20 billion wine bottles sold annually worldwide.

For three centuries there was nothing to fight over—natural cork had a virtual monopoly as the universal wine closure. But over the past two decades many winemakers have become disenchanted with two kinds of cork failure: the musty, wine-wrecking phenomenon of "cork taint" caused by the chemical compound TCA (trichloroanisole) and "random oxidation" that happens when an imperfect cork allows too much oxygen into the bottle, causing the wine to spoil. Depending on whose opinion you ask, the incidence of taint and oxidation can run anywhere from 3 to 15 percent.

Winemakers began turning in significant numbers to noncork closures in the 1990s, especially plastic stoppers and screw caps. Plastic corks now seal about 12 percent of world wine, mainly at the lower end. Screw caps, with about 7 percent of the world market, have made inroads into the high end, especially in the New World (about 45 percent of all Australian wine is now under screw caps, and 85 percent in New Zealand). Until recently, it looked as though cork and screw caps were set for a one-on-one showdown for the hearts and minds of higher end winemakers.

But the battle has changed quickly. A plethora of new high-tech closures has arrived proclaiming superiority to both natural cork and screw caps, and more are on the way. Meanwhile, traditional cork has made a resounding comeback thanks to new quality control measures and expensive R&D. And complicating the battle still further, some critics have accused screw caps of creating new problems of their own.

Changes are coming so thick and fast you could write a book about it, which is what George Taber has done with To Cork or Not to Cork (Scribner), detailing the role this unique bark substance has played through the centuries to the challenges it faces in today's marketplace.

"The pressure on cork is relentless, and the cork companies are naturally terrified of losing their market," Taber says. "It's a $4 billion dollar annual business, and it's not unthinkable that cork in wine bottles could go the same way as cork in medicine bottles. The wine buying public has been patient up to now—I mean, if 5 or 10 percent of luxury cars fell apart on the first drive, it would be a huge scandal."

Particularly worrying for the cork industry is that some very high-end wineries have gone already to alternatives. Although change has come slowly (fewer than 5 percent of European and American wineries have switched), labels using at least some screw caps include Plumpjack, Bonny Doon, Calera, and Hogue in the United States, along with French converts like Paul Blanck of Alsace, Boisset in Burgundy, Bordeaux's Lurton family, and Louis Michel and Domaine Laroche in Chablis.

"Surely the weight of tradition was too much to bear," says Michel Laroche, citing cork failure rates of up to 10 percent. "Beverage, spirit, and pharmaceutical companies switched to screw caps decades ago because they were more reliable than cork," he says, adding that Coca-Cola listed cork taint as a reason for its change. Domaine Laroche was the first French producer to bottle Grand Cru wine under screw cap, and the results have been positive. "Even our village Chablis retains much more freshness under screw cap," says Gwénaël Laroche, Michel's wife. "There's no oxidation and no TCA, and more and more of our customers are welcoming the change."

Miguel Torres in Spain and Germany's Peter Jakob Kühn are among other European makers turning to screw caps, which also are hugely popular with the buyers for Britain's supermarket chains like Tesco.

But other alternatives are gaining ground too. Because screw caps have historical connotations of "cheap" (think jug wines), many winemakers are looking at closures that combine technology with a more upmarket feel.

One is the Vino-Lok, a glass stopper that looks like a decanter plug, which seals itself to the top of the neck via a polymer O-ring: you push it open with your thumbs. It was developed by Alcoa in Germany, with input from the great wine estate of Schloss Vollrads—now a leading customer. Although 2005 was the first full year of production for Vino-Lok, already some 500 European wineries are using it. In the United States, where it goes under the name Vino-Seal, Whitehall Lane began releasing its luxury Napa Cabernets under the closure in early 2006. California's Calera and Oregon's Sineann are also using it on some bottlings.

"Customer reception has been fantastic," says Whitehall Lane winemaker Dean Sylvester. "People get excited when they see it. It's an elegant alternative to screw cap. And customers realize that their $85 bottle won't have taint problems." Whitehall Lane still uses both cork and screw cap on their lower priced wines, but Sylvester says these also might be switched to Vino-Seal despite the higher cost (60 cents, versus 15 cents for screw cap and 30 cents-plus for cork).

Two new stoppers come from Australia, the country that kick-started the screw cap trend in the late '90s. One is Zork, made from injection molded food-grade polymer in three parts. There's a tamper-resistant outer cap that clamps onto the lip of a standard bottle, a metal foil lining inside to block oxygen, and a plunger that fits into the neck. It can be opened by hand and easily reseals. Early users include Don Sebastiani & Sons in Napa and Mr. Riggs and Penny's Hill wineries in Australia's McLaren Vale.

Also from Down Under comes ProCork, a kind of "safe sex" for cork lovers in which a natural cork is sheathed in multiple layers of very fine polymer membranes, which block TCA from leeching into the wine. Launched in 2004, ProCork says it's already selling more than 100 million corks annually worldwide, including Australia, France, and Italy.

Traditional cork manufacturers, fighting for their very survival, are answering strongly. The world's biggest cork company, Portugal's Amorim, says it has spent $60 million over the past six years on R&D and new equipment. It says it has introduced far stricter controls on harvesting, manufacturing, and storage to reduce the chance of natural mold that can cause TCA. It has also developed a new technology for "steam cleaning" natural corks, which it says cuts TCA incidence by around 80 percent.

"There's no doubt the cork industry is making a big effort," says Taber. "They've finally admitted there's a problem after a long period of denial. But we can't fully judge the results yet because of the lag time: many corks won't be pulled out of bottles for years yet. The jury is still out on whether cork can make a full comeback."

The cork industry is also fighting competitors at their own game, with high-tech variations on natural cork. Amorim markets the Twin Top seal for early-drinking wines, in which reconstituted cork particles are topped at either end with treated disks of natural cork. The France-based cork company Oeneo (formerly Sabaté) has developed a cork-based stopper called Diam, using a technique similar to that used for making decaffeinated coffee. Natural cork is ground into 2 mm granules and treated with supercritical CO2 (Oeneo credits an assist from the French Atomic Energy Commission) to extract any TCA molecules. The granules are reconstituted back into cork form with a polymer binding. The company says TCA is thus reduced to "below measurable levels."

Diam sales have risen quickly to nearly 200 million annually, and its 1,800 customers include Stone Street, Freemark Abbey, and Kunde in the United States, and Jadot, Bouchard, Guigal, and Hugel in France. Also on the customer list are the most cork-conscious wine producers of all, in Champagne: Moët, Veuve Clicquot, and Charles Heidsieck have all begun using the Mytik, a Diam variation for sparkling wine, in trials and/or commercial release.

Also experimenting with Mytik is Napa sparkling wine producer Domaine Carneros. "We've had problems with natural cork because we insist that batches show less than 1 percent failure rate, but that's so hard to find that sometimes we have to delay bottling," says Domaine Carneros' president and winemaker Eileen Crane. "We've been testing Mytik for six months, and so far we've found no problems at all. We're aiming to start selling our early-drinking rosé under Mytik by mid-2008, but we want to do several more years' testing before we sell our flagship Le Rêve under the closure, because many customers lay that wine down and we want to be sure."

Some sparkling winemakers are dispensing with corks altogether, opting for crown caps (similar to those on beer bottles). Crown caps have long been used in Champagne cellars to seal wines as they go through their second fermentation: real corks usually are inserted just prior to release. But now some sparkling wines are wearing crown caps on retail shelves, including several Italian Proseccos, and the wines of Moët subsidiaries in the United States, Australia, and Argentina: California's Domaine Chandon sells its top of the line Étoile with a crown seal.

But Australia's leading sparkling winemaker Ed Carr of Hardy's (his wines have won the Melbourne Wine Show trophy for best sparkling white the past 10 years in a row) remains a strong advocate for natural cork. "Time spent under cork is an important part of a sparkling wine's development," says Carr. "It adds lanolin and butter characters. I don't think it's oxygen related, more likely a chemical interaction with the cork itself--we can taste the difference compared with inert closures. And with the improvements in cork production, our TCA rate has fallen to below 1 percent."

Cork is not the only seal accused of causing failures: some wine industry insiders are pointing a finger at screw caps for creating a new kind of problem. They allege that by blocking almost all oxygen from entering the bottle, screw caps can set off a sulphur compound reaction that makes the wine smell like rubber, burnt matches, or rotten eggs, a problem known as "reduction."

The Australian Wine Research Institute has found in its long-term comparative testing that some screw capped wines can have "sulfide/rubbery" aromas. Cork makers and the manufacturers of other alternative closures say their products are far less likely to cause reduction because they let in tiny amounts of oxygen. Some Australian and New Zealand wineries have even gone from screw cap back to cork. But not all experts agree.

Australia's Stephen Henschke, whose family company makes the famed Hill of Grace Shiraz, has been trialing screw caps since 1995 and decided to put his entire commercial output under screw caps in the 2005 vintage. Henschke, who's also considering using Vino-Lok seals, says reduction is more likely a winemaking fault. "If the wine is squeaky clean at bottling, screw cap or Vino-Lok will encapsulate the quality and let it develop. But if the wine is faulty, the fault gets encapsulated too. At one recent Australian wine show, the judges looked at all the wines with reductive problems, and half of them were under cork, so it's not the closure."

"Cork is eighty percent air," says Philip Laffer, chief winemaker for Australia's Jacob's Creek, "and that air makes its way into the wine after bottling, helping prevent reduction. That doesn't happen with screwcaps." Laffer, a fan of screwcaps, says his team has solved the problem by using different yeasts that are less prone to creating reductive characters. "Also we keep our wines in tank longer before bottling, to make sure reduction is not going to happen."

Peter Gago, chief winemaker for Australia's Penfolds Wines, says reduction "is a real issue. Sometimes we have to quadruple-decant a screw cap red to get rid of unwanted characters, but they do blow off with decanting. I think the reductive issue is way overstated--I'm more worried about whether screw caps will physically remain a good seal over 30 or 40 years' storage."

Which raises another central point: Experience shows that good corks allow wines to develop perfectly for decades, whereas the newer closures require a leap of faith because there is no track record.

Or is there? When Australia's Yalumba winery decided to bottle their Rieslings under screw caps in the 1970s, the public just wouldn't buy them, and the company had to return to using cork. As a result, there's a trove of old screw cap Rieslings in Yalumba's cellars, and when winemaker Louisa Rose opened a 1980 Pewsey Vale Eden Valley Riesling in New York recently, it was in perfect shape, developed yet fresh. "This wine has aged purely, gaining toast and honey characters," says Rose. "With a perfect cork you get that too, but most corks are not perfect. Our Rieslings under cork from the early 1980s don't have the same bright color or flavors, and many have fallen away completely."

Many winemakers accept noncork closures for whites, but what about reds? Trials have been going on in cellars around the world, with differing conclusions. Paul Draper, chief executive and winemaker at California's Ridge Vineyards, has been testing alternative closures since the early 1990s and has rejected all of them so far.

"We've found that plastic corks and the Vino-Seal allow in too much air and cause the wines to age too rapidly," he says. "Conversely, under standard airtight screw caps, the wines hardly age at all, whereas with cork the wines develop the complexity with time that we're looking for. We're not sure how, but it seems some air penetrates the cork or is released from within the cork, making the wine more complex. We haven't yet found a closure that will do that better than cork.

"We test all our cork samples very rigorously and often reject batches. Nothing's foolproof, but we've kept cork failure down to around 2 percent. We haven't tested Diam because a conglomerate cork is not really a cork, but we'll keep looking at anything interesting that comes down the pike."

By contrast, Henschke says the first reds he put under screw cap in 1995 "have developed beautifully. They do age more slowly than with most corks, in the same way wine ages slower in a bigger bottle like a double magnum. It's a misconception that wines need extra air through a cork. In fact, French research from decades ago showed that wine ages better without additional air, and the AWRI's recent research has shown that the best corks act just like a screw cap, by keeping oxygen out."

Penfolds have been conducting a long-term trial since 1996, bottling two lots of their Bin 389 Cabernet-Shiraz under cork and screw cap. The two wines recently were served "blind" to a group of experts, with surprising results. "No one could tell which was which," says winemaker Gago. "But the overwhelming preference was for the wine under cork—it was more complete, more developed, yet still vibrant. I suppose the moral is that a perfect cork can't be beaten—but there's an element of Russian roulette because there aren't too many perfect corks."

Gago says Penfolds will soon begin trials with the prototype of a pure glass-on-glass stopper (without any O-ring interface like the Vino-Lok). "Glass-on-glass is truly neutral, and we're confident wines will age in an airtight seal," he says. "But we have to see if the mechanics of it will work, along with the aesthetics and marketing."

Amid all the new products and myriad points of view, there is one point of agreement: No one really knows where all this is heading. "It's all changing so fast," says Henschke. "Probably neither screw caps, Vino-Lok, nor cork will be the final word. Someone will likely come up with an innovation to eclipse everything."

Laroche foresees compromise. He likens the closure debate to the arguments of the 1970s when stainless-steel fermentation tanks first appeared as an alternative to oak barrels. "There was a distrust of tanks, and consumers believed good wine could be made only in barrels. Now winemakers have found a happy balance between barrels and tanks, and I'm certain that corks and technical closures will learn to coexist."