Chehalem pinot noir offered a chance to judge how wines age under screw cap closures. (by Dave McIntyre)

A decade ago, many wineries started using screw caps as closures on wine bottles. They were rebelling against a spate of poor-quality corks that ruined wine. A “corked” wine has been spoiled by a chemical that taints the cork during manufacture; its effects can range from a subtle deadening of the wine’s fruit to an obvious, putrid smell best described as “wet cardboard” or “moldy basement.” Yet turning to screw caps was considered a bold move. Would consumers reject them as a symbol of Skid Row rotgut? And would wines age as well under screw caps as they do under natural cork?

Consumers embraced the new closure, and the increasing popularity of screw caps forced the cork industry to improve its quality. But the question of aging persisted; screw caps today are most popular on white wines generally intended for early drinking. How wines will age under screw cap is a question only time can answer, after all.

But now we have data. And Harry Peterson-Nedry, founder and co-winemaker with his daughter, Wynne, at Chehalem Vineyards in Oregon’s Willamette Valley, says he is convinced that screw caps not only preserve his pinot noir wines but help them age well. He recently offered a 10-year retrospective tasting for members of the D.C. wine trade to prove his point.

The wines we tasted were from 2013 back through 2004 of Chehalem’s Three Vineyard Pinot Noir, a blend of grapes grown on three soil types throughout the Willamette Valley. The current vintage retails for about $35. They showed a consistency of style, with the bright red-fruit flavors and silky texture that make Chehalem one of Oregon’s top pinot producers. They were also remarkably fresh, the 2005 especially showing surprising acidity, with lots of primary (original) fruit flavors and just a hint of the color change that comes with age.

Peterson-Nedry explained that he began experimenting with alternative closures in 1994 after finding as many as 8 percent of his wines had been tainted by bad corks. After plastic “corks” proved faulty, allowing young wines to oxidize in bottle, he settled on the Stelvin brand of screw caps. (Stelvin is a French brand, and the most commonly used screw cap on premium wines.) He bottled his unoaked chardonnay, called Inox, under screw cap beginning with the 2003 vintage, and all but single-vineyard and reserve pinot noirs and chardonnays beginning in 2004. Since the 2008 vintage, all Chehalem wines have been capped with Stelvin.

“We found the screw caps gave us several advantages over natural cork,” Peterson-Nedry says. “They eliminate cork taint, of course. They also prevent premature oxidation, and they preserve sulfur dioxide levels in the wine to guard against brettanomyces and other faults.” Brett is a yeast that can give wine unpleasant flavors charitably described as “barnyard.” Chehalem is also experiencing less bottle variation under screw cap, he said.

No such flaws were apparent in this decade of pinot noir, though we noticed vintage differences. The outstanding 2012 was ripe and round, while the 2011 and 2007, considered “lesser” years at the time, were sleek and elegant. Three years — 2009, 2006 and 2004 — were unusually warm for Oregon. Wines from those years were the only ones in the lineup that topped 14 percent alcohol. Although the 2004 showed well and was a crowd favorite, the 2006 and 2009 lacked the freshness and vibrancy that characterized the rest of the wines.

And how well did they age? Removing the hotter years as outliers, the 2005, 2007, 2008 and 2010 were exceptional, suggesting that the wines profit from five to 10 years in a cellar.

Wine is commonly thought to benefit from the small amount of oxygen seeping through a cork over years of cellaring. Screw caps can be customized with cap liners that allow just a bit of oxygen into the wine. Yet Peterson-Nedry uses tin liners that are impervious to oxygen, which he insists is wine’s enemy.

“The wine chemists tell us aging is anaerobic and doesn’t require extra oxygen,” he said.

This tasting suggests that screw caps do allow wines to develop secondary characteristics as they age and might even slow that process, preserving the wine’s initial fruit characteristics over many years, assuming the wines are stored properly. More such tastings are called for; pairing the same wine over many vintages under both natural cork and screw cap would be ideal. But as we see these initial results from innovative wineries such as Chehalem, I suspect more producers will be willing to bottle their top wines under screw cap.

McIntyre blogs at dmwineline.com. On Twitter: @dmwine.