Closure Wars

Cork vs. synthetic cork vs. screwcap vs. everything else—a report from the front lines.


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Brendan Eliason, winemaker at Periscope Cellars, one of northern California’s urban warehouse wineries, studied industrial design and packaging when he was in college. “When I got interested in wine,” he says, “I was astonished to find that the packaging was 300 years old. There’s no other product on earth like that.”

Until 20 years ago, there was really only one way to seal a wine bottle: put a cork in it—unless you wanted to use a screwcap and aim for the Skid Row market. Those simple days now seem as far away as the era of wine stored in stone amphorae.

The ongoing closure debate is the most contentious issue in the world of wine. Claims and counter-claims abound on the merits and demerits of natural corks, synthetics, screwcaps and a host of other bottle-toppers. Major money is being thrown around to fund research, influence public opinion, gain market share and charm journalists. All the closure types have advantages and limitations; all of them, under intense competitive pressure, are getting better; and any one of them can still, alas, take the fun out of your dinner party. Here’s a field guide to the closure wars.

The TCA funk
 

In the late 1980s, rising worldwide demand for wine led cork producers to ramp production up and standards down, resulting in a wave of bad corks and worse press. The culprit was identified as TCA (2–4–6 trichloroanisole), which, along with a gaggle of unpleasant chemical relatives, gives wine a moldy, funky character that renders it undrinkable. At lower levels, TCA simply makes wine musty and boring. And TCA was doing this to a lot of bottles—estimated at 5–10% at the turn of the millennium—including some of the world’s best wines.

Cork producers, enjoying a virtual monopoly, initially denied the problem existed. “For people in the industry,” says Daryl Eklund, general manager for Amorim Cork America, “it took a big mindset change.” Nothing changes a mindset like losing a third of your market, which happened with the rise of synthetic corks in the 1990s.

Since that rude awakening, cork quality has improved considerably. The major cork companies, especially in Portugal, have spent tens of millions of dollars retooling every step of the production process. For both solid-body corks and agglomerate versions made from ground cork, top producers test and test again, using high-tech analytical methods straight out of the lab on CSI. In the U.S., the Cork Quality Council, a Napa-based consortium of seven major cork producers, works with ETS Laboratories to sample every batch of corks coming into the country. The CQC’s Peter Weber says there has been a 91% drop in TCA incidence in shipments from Portugal since screening began in 2001.
 

Purdue University enologist Christian Butzke, a longtime cork/TCA critic, concluded in May, 2009 that “from both a winemaker’s and
consumer’s perspective, TCA is no longer a major problem for the American wine industry.”

Plastic fantastic stoppers
 

The first alternative to take a bite out of natural cork was plastic closures—shaped like natural corks, but made from synthetic polymers. Several flavors of synthetics hit the market in the 1990s—molded versions, extruded versions, stoppers with or without outer sleeves, stoppers in every color of the Day-Glo rainbow—and quickly gained followers. Synthetics were inherently TCA-free and, better yet, much, much cheaper than natural corks, a huge economic driver.

Synthetics, however, soon exhibited problems of their own. On the irritating side, many tended to stuck to the neck of the bottle after a few months or years of storage, becoming nearly impossible to remove. St. Francis Winery in Sonoma County, the first major California synthetics adopter, switched suppliers in 1995 because of stuck stoppers; as winemaking director Tom Mackey puts it, “The incidence of cork taint is zero, but if you can’t get it out of the bottle, there’s no point in having the philosophical discussion.” The leading synthetic producers now claim the problem of “grip” has been addressed, but the impression persists.

A more serious problem surfaced in controlled studies including aging trials conducted by the Australian Wine Research Institute (AWRI): oxidation. After a year or eighteen months, wines with synthetic closures regularly showed the ill effects of too much oxygen, permeating through, rather than around, the stoppers. For wines consumed soon after bottling, this weakness hardly mattered. But for wines, particularly reds with aging potential, the issues were troubling. At St. Francis, the vast majority of its output gets the synthetic treatment, but wines expected to age anywhere from five to fifteen years bear natural corks.

Synthetics producers have reformulated their materials to reduce permeability, and different models now come rated as three-year stoppers, five-year stoppers, and so on. Olav Aagard, research director for Nomacorc, by far the leading producer of synthetics, says they are now able to “tune the amount of oxygen going into the wine so that an ideal closure/wine evolution combination can be achieved.” Nomacorc is also working with several international wine research centers on a multi-year study of oxygen and wine aging; work so far has underscored the role and importance of oxygen in the bottle and produced sophisticated new methods for accurate oxygen measurement.

The screwcap twist
 

Screwcaps have been around much longer than synthetic corks, notably for spirits packaging and large-format jug wines. When Australians tried putting screwcaps on premium wine in the 1970s, consumers resisted. But with cork on the defensive, screwcap adoptions in the last decade have come on fast. Whole national wine industries have abandoned cork: New Zealand now puts over 90% of its wines under screwcap, Australia 80%. Their bargain pricing more than makes up for any lack of glamour.
Perhaps through reverse snobbery, the migration of screwcaps from downscale to upscale has generated lots of buzz. When Randall Graham gave up synthetics for screwcaps for his Bonny Doon wines, people noticed; when the PlumpJack winery started bottling half of its $100 Reserve Cabernet in Stelvin closures, ditto.

Screwcaps, alas, have a potential Achilles’ heel, too: not enough oxygen may get to the wine. In repeated trials, some portion of wines under screwcap developed noticeable levels of sulfur-related odors, aromatic qualities winemakers refer to collectively as reduction. Worst case, the wines conjure up rotten eggs and burnt rubber; in lower concentrations, the sulfur compounds cover up the fruit. Keeping these sulfides in check requires oxygen—just about exactly the amount of oxygen let in by the best natural corks. Ironically, the most outspoken critic of screwcap reduction has been Alan Limmer, a leading chemist and winemaker in screwcap-happy New Zealand.

Screwcap reduction may not matter for wines consumed soon after bottling—a lot of wine. Advocates also point out that any off aromas aren’t caused by the screwcap itself—in the way that cork TCA pollutes wine—but rather stem from the sulfur chemistry of the wine. Careful winemaking, screwcappers argue, can solve potential problems before bottling; skeptics are not at all convinced. Screwcap producers are experimenting with various liners that go inside the outer, aluminum shell, allowing in different amounts of oxygen. Bruno de Saizieu, marketing director for Stelvin, the largest screwcap producer, notes that some winemakers like a little reduction in their wines, and some don’t, and so his company’s mission is to provide a range of options for oxygen management.

Waiting for perfection
 

But wait: there’s more. With the natural cork/TCA problem receding, two new fronts have opened up in the closure wars: environmental stewardship and bottle variation.

Led by Amorim, the world’s largest cork producer, natural corkers highlight the fact that their stoppers come from sustainable sources—forests—which trap carbon dioxide, keep land in agricultural use, prevent desertification of the Iberian landscape, and support a traditional way of life. Synthetic corks and screwcaps, on the other hand, are mainly made from petroleum and aluminum. The Rain Forest Alliance has recognized Amorim for its role in forest preservation, and similarly commended Oregon’s Willamette Valley Vineyards when it switched to using only Amorim’s corks. Amorim has also launched ReCork America, a program to collect and recycle natural corks. Are the cork companies trying to change the subject? Of course—but they may still have a point.

Cork critics would like to change the subject, too—to the issue of bottle variation. Synthetic corks and screwcaps, being engineered products, promise consistency, something natural corks can never deliver: their very “naturalness” means some bottles of a given wine will get a little more oxygen over time, some a little less, creating differences in aroma and flavor. How much this potential variation matters to the average wine consumer has yet to be shown.

Cork Supply USA plays the field, selling natural Portuguese corks, Nomacorc synthetics and SAVin screwcaps. Marketing manager Ron Glotzer says their research indicates that natural corks are still on top in the U.S., with about half of the still wine market; synthetics account for a little over 40%; screwcaps about 8%. While he sees screwcap sales growing, natural cork still commands strong consumer preference, associated with tradition, romance and quality.

Meanwhile, Eliason, winemaker and student of packaging, who seals all his wines under screwcap, thinks the real problem may be putting wine into bottles at all. Bottles weigh as much as the wine they hold; shipping them around the world runs up an enormous carbon cost; and as soon as the bottle is opened and exposed to oxygen, its contents start to deteriorate. Most wine, he muses, should be put in bag-in-boxes, which perform better on every count.

The closure wars promise to have a long shelf life.
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