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Turmoil at the Top

Winemakers continue to wait for the perfect stopper

Daniel Sogg
Posted: October 22, 2001

Plumpjack boldly chose screw caps for its high-end Napa Cabernet.
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Who wants to be a multimillionaire? Simply design the perfect wine-stopper. How difficult can that be in the 21st century?

Very difficult, apparently. The ideal stopper must satisfy a variety of criteria, many of which appear incompatible. Stopper material must be compressed into the neck of a bottle, then expand to protect the wine from oxygen. It must be easy to extract and reinsert, but durable enough to last for decades. The stopper must be able to survive direct contact with the wine without imparting any unpleasant aromas or flavors. It must also be an affordable product accepted by the consumer.

Any winners? Well, don't feel too bad -- no one else has been able to get it just right. Cork, processed from the bark of the cork oak, has been the stopper material of choice since the early 17th century, yet its flaws are evident to anyone ever disappointed by a "corked" bottle.

When everything works, wines can age beautifully for decades in cork-sealed bottles. Many modern winemaking techniques developed in direct response to the conditions created by cork, which allows minuscule amounts of air to reach wine, catalyzing maturation.

But only a tiny fraction of wines are built to last. And improvements in wine quality over the past few decades have highlighted big problems with bark plugs. The major villain is trichloroanisole, or TCA, a substance endemic to cork forests and the production process. At low levels, it mutes a wine's aromatics and flavors. At higher concentrations, it reeks of moldy newspapers, or of cardboard rotting in a damp basement.

Infinitesimal amounts of TCA can spoil a wine; many people detect the substance at around five parts per trillion. To put the ratio in perspective, that's comparable to a couple dozen grains of salt in an Olympic-size swimming pool. And all it takes to form TCA is an interaction of phenol (an organic compound found in all plants), mold and chlorine. Each of these components is commonplace, so TCA continues to plague the industry.

Like any natural product, cork can also have structural flaws. Those flaws can allow too much air to reach a wine, leaving it flat and stale due to oxidation. And while many factors (most notably storage conditions) can contribute to the unpleasant phenomenon of bottle variation, cork is probably the major cause.

Today, cork's dominance looks to be dwindling. In the 2001 Wine Spectator Readers' Choice Poll, 40 percent of respondents endorsed a switch from cork to synthetic stoppers. This growing dissatisfaction with natural cork has spurred development of many alternatives.

Some traditional cork producers now offer so-called technical stoppers, which are made from a combination of natural cork and synthetic products such as glue. But just like natural cork, these stoppers are susceptible to TCA taint.

Since the early 1990s, there has also been a burgeoning market for polymer-based synthetics. They usually cost about 7 to 15 cents, a bit less than medium-grade natural corks. The first efforts were failures: The stoppers imparted unpleasant plastic flavors, were difficult to extract and didn't prevent oxidation. But quality has improved dramatically. One of the most popular products is Supreme Corq, whose manufacturer this year expects to sell more than 100 million stoppers to 600 wineries worldwide.

Supreme Corq, like other synthetics, has been a work in progress, and the jury is still out regarding its long-term (more than two years) storage capabilities. Recent evidence indicates that wines sealed with synthetic stoppers oxidize faster than bottles plugged with high-quality natural corks. So the current products might suit wines meant to be consumed no more than a year or two after bottling.

But the technology should continue to improve. Supreme just released a new stopper, Preservera, designed for wines meant to age. Bonny Doon Vineyard, in the Santa Cruz Mountains, once used Supreme for all its wines, but concerns about oxidation led the winery to shift to Preservera, other synthetics and cork for their high-end reds.

Neocork Technologies, based in Napa, makes a synthetic with a foam core and elastic skin. The company expects sales of more than 100 million stoppers this year to its 120 mostly domestic clients.

Another popular synthetic, Nomacorc, should sell more than 400 million stoppers this year to international clients. Nomacorc distributors acknowledge that the product is best for no more than two years of storage, but add that modifications could soon double the recommended shelf life.

While traditionalists, snobs and romantics might shudder at the notion, screw caps currently seem to offer the best protection against oxygen and cork-related TCA. Current evidence suggests that screw caps allow less air seepage than corks do, meaning they'll do a better job preserving the freshness of early-drinking wines.

Screw caps were once relegated only to jug wines. Upscale Napa producer PlumpJack made headlines recently when it chose the Stelvin brand twist-off for its $145 Reserve Cabernet. But it's about the only high-end red wine producer to take that plunge. Even though screw caps may have the best résumé, most winemakers will probably offer the job to better-looking applicants.

In general, most winemakers don't yet understand the finer points of long-term storage with screw caps. If the seal is so good that no air whatsoever gets into the bottle, a wine will evolve differently than it does with a cork (though estates might be able to tinker with production techniques to offset those differences). Nonetheless, some producers aren't bothered by the prospect of slower maturation. "If you take out a 15-year-old Cab and it tastes like a 10-year-old Cab, I don't see that as a problem," says Michael Beaulac, winemaker at Markham Vineyards in Napa.

Crown tops, commonly used on beer bottles, are another radical option. Despite their image, they have a long track record with Champagne and sparkling-wine producers, who use them to seal bottles during secondary fermentation. Such wines can last for years.

Perhaps time will demonstrate that there is no such thing as a perfect stopper. Definitive answers require experimentation. Estates routinely apply a range of production techniques to different sites and grape varieties. So why not take that same innovative spirit to the top?


For the complete article, please see the Oct. 31, 2001, issue of Wine Spectator magazine, page 77. (Subscribe today)

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