Napa, Calif. -- The ongoing wine industry debate over closures, in which natural cork producers are often cast as the villains, took at least a slight turn Saturday during a live debate about the issue at Copia. Much of the discussion, fueled both by the debaters and the audience, focused on the issue of "reductive" aromas in screwcapped wines.

With two panelists quoting evidence of marked improvement in cork taint in natural corks, and the representative of Portugal's biggest natural cork company, Amorim, presenting the case for cork as the greenest closure, the most controversial topic appeared to be the development of earthy aromas in some wines aged under screwcaps.

When you consider that winemaker Randall Grahm of Bonny Doon Vineyard in Santa Cruz, Calif.--who presided over a theatrical funeral for the natural cork several years ago--was on the panel, acknowledged that he has some concerns about screwcaps and continues to experiment with natural corks, it may be that the anti-cork tide has slowed.

Probably the toughest anti-cork comments during the hour-and-a-half session moderated by George Taber, the author of a new book, To Cork or Not to Cork, came from the audience. Jerome Zech, CEO of winebid.com and former CEO of synthetic stopper maker Supreme Corq, asked the speaker from Amorim, Carlos de Jesus, why his company didn't expand into other stoppers rather than sticking with TCA-troubled corks.

De Jesus, the marketing and communications director for Amorim, had probably answered the question already, when he said in his opening remarks that Amorim had the best sales year in its history in 2006, selling 3 billion natural cork stoppers worldwide. Natural corks have lost market share to synthetics and screwcaps, but Amorim's business has been growing.

Both Grahm and an expert considered neutral on the topic, Pascal de Chatonnet of Excell Laboratory near Bordeaux, France, addressed the reduction issue (See Reductive Reasoning, August 2007 issue of Wines & Vines) in their opening remarks and fielded audience questions on it later. Chatonnet cited numbers from an ongoing survey of TCA-tainted corks in a big annual wine competition in the U.K. He said the incidence of wines confirmed by lab tests to be corky had dropped from 4.9% in 2003 to 0.2% in 2006.

Chatonnet said all the closures have their problems--rapid oxygenation in many synthetic corks, TCA taint in natural corks, and reduction with screwcaps. He said not to fear the word "reduction." because "The nice development of wine is a reductive development. Screwcaps are perfectly able to age a wine." He said the problem of so-called reductive aromas, really the product of thiols or mercaptans, can come as a result of the screwcap liners. "We have no tools to give the winemaker to analyze the capacity of a wine to develop these negative aromas," he continued.

In response to a question, Chatonnet said he knows of no particular advice to give winemakers worried about reductive aromas developing in their wines. He said wines can be completely stripped of the precursors for reductive aromas, but that the process will "eliminate the typicity of the wine."

Grahm, who has moved production of Bonny Doon wines into screwcapped bottles, says he is using less sulfur dioxide in processing his wines as part of a plan to keep the chi or life force of his wines as vital as possible, and thinks that may help reduce the risk of negative reduction aromas. But he stated that in many of his wines, especially red Rhône-style wines, a modest reductive aroma seems correct to him, based on traditional styles in the Rhône and the nature of the aromatic properties of Syrah and other Rhône varietals.

He said that a young wine is like a young person--it needs a lot of oxygen or a lot of exposure to the world, but as it matures, it often does better with less exposure. His view is that a winemaker needs to add oxygen to young wines until the tannins become softened, and then stop. From there on, the maturing process is a reductive one, Grahm said, and screwcaps create a reductive atmosphere that helps a wine age well.

Grahm said he would welcome a closure that allows more oxygenation shortly after bottling, but becomes tighter later.

De Jesus of Amorim argued for natural cork as a sound choice for wineries concerned with the environment and with consumers interested in green products. He referenced his company's recent sustainability report and other research in which the company estimates that cork forests retain 14 billion tons of carbon dioxide per year. "Natural cork is the only wine-specific packaging option that addresses all five of the most important issues in the areas of environment, sustainability and CO₂ reduction."

Bruno de Saizieu, the commercial and marketing director of Alcan Packaging Capsules, who worked for many years with Stelvin (the leading world's screwcap producer), noted his company's 25% reduction in CO₂ emissions from 2001 to 2005. And he stressed that the world marketplace is increasingly accepting of screwcaps. He said that Alcan's screwcap sales worldwide are now 2 billion per year. Australia's has gone up to 65% screwcaps, a 20% jump in two years, he said, and New Zealand now uses 90% screwcaps.

"The screwcap is way better than the natural cork," he said, and noted that more high-end wines are adapting them, including chateau-bottled wines in Bordeaux and at least one grand cru burgundy, a Boisset Chambertin.

Grahm continues to experiment with corks, bottling a small quantity of his highest priced Bonny Doon wine, le Cigare Volant, with natural corks for comparison against the commercial bottling with screwcap. "Cork does impart a certain quality to the wine," he said. "It's not necessarily taint." Even in bottles with no taint there can be a slight difference--positive or negative depending on the consumer's preference--in aroma and flavor, he observed.