As part of its 10th anniversary celebration this fall, PlumpJack Winery let friends of the winery and a number of wine writers take part in a noble experiment.

Eight years ago, the folks at PlumpJack decided to invest in a bottle closure other than traditional cork. PlumpJack bottled a substantial amount of its best wine, the 1997 reserve cabernet sauvignon, with screw caps.

During a recent celebratory gathering at the winery on the north side of Oakville Crossroad , we were asked to see if we could determine which glass of ’97 reserve cab had been poured from a cork-aged bottle, and which came from the screw cap.

As way of explanation, founding partner Gordon Getty said he’d made the decision to bottle the prestige wine with screw caps after having a discussion with son, Bill, and partner Gavin Newsom, current mayor of San Francisco, regarding cork taint.

“Gordon wanted to know why cork taint was acceptable (in the wine industry today) and if there were any other closures that would prevent it,” said winery general manager John Conover.

“Screw caps on a  $165 bottle of wine? People thought we were crazy,” he added.  But they did it, he  said, and the initial offering of the reserve ’97 cabernet with screw cap closures took place at Auction Napa Valley in 1999.

Conover noted the winery has held onto some of the wines with both cork and screw cap closures. “Now  we’re offering customers an opportunity to take part in our experiment.”

So those of us at the 10th anniversary celebration sniffed and swirled, and we sniffed and swirled again and again. We were asked to guess which glass held which wine and also which one we liked  best.

Truth be told, there were very subtle differences in the two wines. This sipper felt Glass A benefited from more aromatic notes, while Glass B seemed to have better integrated flavors. I preferred Glass A; Getty said he liked B, but only by a hair.

And it seemed that tasters were pretty evenly divided over which wine was preferred. Turned out Glass A contained the cab poured from a bottle with screw cap, Glass B the cork closure.

Upshot, I guess, was that both wines were excellent, and Getty and winemaker Tony Biagi could take heart in knowing that the screw cap was not all folly.

The other good news that evening also came in a glass. We got to taste the first release from Cade, PlumpJack’s sister winery now under construction up on Howell Mountain, as well as the newest reserve cab and reserve chardonnay releases. Here’s our thoughts on the trio:

Cade Winery 2006 Napa Valley Sauvignon Blanc ($26, screw cap): Blended with a small amount of semillon (7 percent) from Rutherford, the grapes for this inaugural release came from established vineyards in Oakville and Rutherford. Slightly less than one-third of the wine was aged in new French oak barrels, which undoubtedly accounts for its lush, elegant finish.  Its primary bouquet is that of lemon and lime with a subtle orange blossom note.  There’s bright acid with a dazzling lemon finish, plus undertones of figs and ripe melon.

PlumpJack Winery 2006 Reserve Chardonnay ($46, screw cap): A third of this fruit forward chardonnay was fermented in oak. As it did not go through malolactic fermentation, it’s a lovely crisp chardonnay with aromas and flavors of apples and citrus, with a lovely drop of vanilla on the finish.

PlumpJack Winery 2004 Reserve Cabernet Sauvignon ($400 for a 2-pack, 1 cork finish, 1 screw cap): This is a big, brawny cabernet that Gordon Getty says is a “smashmouth” wine. It smells of ripe black plums and tastes of Bing cherries, with an underpinning of dark chocolate and a bit of tannin on the finish. A well-balanced wine, this one should age well with either closure.