When you zipped up your pants this morning, did you question whether that was the best way to keep them from falling embarrassingly about your ankles? At the dawn of the 20th century, the inventors of the trusty zipper wondered whether consumers would accept it as a method of closure for clothing. Today there is another closure causing debate, this time in the wine world. Just as the button-down crowd initially fought tradition before giving in to progress, cork defenders are having a difficult time embracing the screw cap, though its proponents are confident of the benefits of this “radical” device. The traditional cork closure has come under scrutiny as winemakers and consumers question its ability to prevent oxidation or other spoilage problems that change the wine’s flavor. At the same time, centuries of tradition are tied up in the mystique of wine-opening “ceremonies,” and many wine-lovers are reluctant to ditch the cork and turn to the screw cap. Recent research, however, is bringing more around to the cap camp. Cork Bark’s Bite Wine professionals estimate that 3 to 5 percent of all bottles of wine sealed with corks is contaminated from exposure to air or from the cork material itself. Natural corks, made from the bark of the cork oak, may fit poorly from the outset, or may dry out as they age and allow too much air to seep into the bottle, causing oxidation.  Contamination derives principally from the chemical compound trichloroanisole, or TCA. “Corked” wine, the term used to describe wine that’s been affected by tainted corks, can have a bad odor and a flavor of moldy wet cardboard or newspapers when a high TCA level is present. A noticeable musty quality is evident at moderate levels, and even low TCA levels can make the wine seem lacking in fruit flavors and richness. These undesirable effects have led winemakers to seek out alternative closures.  Some wines are sealed with synthetic corks (approximately 9 percent), but these can be difficult to remove and may also affect flavor. The best-known screw cap is the French-made Stelvin. It sports a long aluminum sleeve that fits over the bottle’s neck, giving it a similar appearance to traditional cork-sealed bottles. Stelvin closures have been around since the 1970s, but they’ve had to battle the image problem of screw caps being associated with inexpensive and mediocre wine. Their convenience, however, can’t be denied—the bottles can be stored upright and a simple twist opens the cap and seal without wrestling with a corkscrew. The Proof is in the Pour Many winemakers are now opting to use screw caps on their higher quality wines in light of recent research that proves their ability to keep wines fresh and avoid contamination. Australia and New Zealand have led the way, favoring the cap first for use on Rieslings, and then on some of their red wines. In a recent four-year study conducted by Washington state’s Hogue Cellars, a panel of Hogue winemakers and trade professionals tasted and compared samples of Merlot and Chardonnay closed with natural cork, synthetic cork, and the Stelvin screw cap. The results showed screw caps to hold fruit flavors and maintain freshness more effectively than either natural or synthetic corks. As a result of the study, Hogue bottled its entire line of 2004 Fruit Forward Wines (which represents 70 percent of the winery’s total production) with Stelvin screw caps. Other winemakers in the United States and Germany are following suit, and even French vintners are beginning to try them on some of their white wines.  Studies continue in an effort to determine screw caps’ long-term aging potential, but fans of the cap are hopeful.  In any case, approximately 90 percent of wine is consumed within a few years of bottling, and screw caps seem to be well suited to white wines and reds intended to be drunk young.  With much reverence, ceremony, tradition, and emotion tied up in a small piece of bark, there will always be those who prefer to sit in their button-flys and sip their wine through cork particles.  But they may someday have to take a turn toward screw caps as winemakers increasingly embrace the trend.