eatvancouver.net

Science Feature

Screwy Solutions

By Darryl Korell
A special to Eat Vancouver
Saturday, February 18th, 2006

California’s PlumpJack winery is well known for its Reserve Cabernet Sauvignon wines, which sell for about $155 a bottle. But it is not their taste or their price that makes them noteworthy; these PlumpJack wines have screw tops.

It used to be unimaginable to see anything other than cork when purchasing more expensive wines. But, today, many wineries such as Calera, Sonoma-Cultrer, and Wolf Blass put screw tops on some of their higher end wines.

The reason for the switch is not cost; it is quality – something that never used to be associated with screw top wines. Corked wines have a greater chance of developing problems with 2,4,6 trichloroanisole (TCA), a potent compound that taints wine.

“TCA causes a wine to smell and taste musty, moldy, and mushroomy in higher concentrations,” says Corrie Krehbiel, associate winemaker at Cedar Creek in Kelowna. When someone sends back a bottle of wine at a restaurant, TCA is usually the culprit. A single drop will make your wine taste bad and it affects 2 to 10 percent of all bottles. It is a multi-million-problem for the industry. Winemakers and scientists have struggled – and have failed – to find ways to stop TCA from forming

They are now turning to o screw-on twist caps and synthetic corks as a way to bypass the TCA problem. These alternatives to cork are the hottest topic in today’s wine industry as winemakers increasingly change bottling methods to prevent TCA from spoiling their wine.

Researchers believe that TCA develops when chlorinated products, such as water or cleaning agents, are used in close proximity to moldy wooden surfaces. Cork often develops mold when bottled and any past contact with a chlorine-based product can create TCA.

Even though chlorine is supposed to eliminate mold, TCA can still form. “It is a problem of concentration,” says Giacomo Zara, a microbiologist at the University of B.C.’s wine research centre, “Not every product you use is able to eliminate something 100 percent.”

Although cork is most commonly attributed to the development of TCA, other wooden objects in wine cellars can also acquire it: storage barrels and the beams in the ceilings can be TCA breeding grounds, leaving many chances for wine to become contaminated with TCA even before it is bottled.

Many wineries are doing all they can to eliminate this problem. At Cedar Creek, they avoid using chlorine-based products. “We minimize the risk of in-winery TCA production by ensuring that cleanliness and sanitation are top priorities,” Krehbiel says. “Our use of chlorinated compounds is restricted to stainless steel only.” Winemakers at another leading B.C. winery, Mission Hill in the Okanogan Valley, also use alternatives to chlorine when cleaning their facilities.

The winemakers also carefully select the type of cork they use to further minimize any chance of contracting TCA. “Good quality, clean cork can absorb TCA out of wine,” says Wade Stark, Mission Hill’s assistant winemaker. For all bottles over $15, Mission Hill uses what they believe are the best types of cork – a one-piece, all natural, cork. For their lower quality wines, they will use a glued, two-piece, cheaper agglomerated cork, which carries a greater risk of attracting TCA.

Cedar Creek uses high quality corks for their better wines as well. But they use a plastic, synthetic, cork for their lower end, ‘classic’ wines. Unlike natural cork, these synthetic corks do not let the wine breathe. But they almost eliminate the risk of TCA taint. “The capability of aging with synthetic corks up to three years is well documented,” says Krehbiel. “At this time, we are using synthetics only for those wines that we believe will be consumed before three years.”

In addition to synthetic cork, wineries are opting for an older, cheaper and possibly better substitute – the screw top.

Like synthetic corks screw caps, which are usually made of aluminum, cannot contract TCA.

Traditionally, screw tops have been reserved for cheaper, lower end, brands of wine. Consequently, they have garnered a bad reputation. Many in the wine industry, however, hope to reverse the stigma because screw tops offer big advantages.

A screw cap’s drawback is that it is not as permeable as traditional cork. No one has been able to determine if screw caps can properly store wine for aging.

Stark says screw caps are much better than plastic corks. “Synthetic cork affects the wine,” he says. “You get a plasticization of the wine and it’s hard on the environment.” He says screw caps are the way of the future. “We have put screw caps on a couple of products and we are waiting to see how the reception is going to be.” A screw cap’s main drawback is that it is not as permeable as traditional cork. No one has been able to determine if screw caps can properly store wine for aging.

But even if cork is permeable, it can sometimes become dry and rotten, spoiling the wine. Screw tops could eliminate that problem. “It is easy,” Stark says, “after ten years you can unscrew the cap and put on a new one.” The wine’s aging process could then be improved by adding the correct amount of oxygen each time the winemaker changes the cap. “With cork you are doubling your risks of TCA every time you change it,” says Stark.

The question, of course, is whether British Columbians will buy screw top wines?

Jeff McDonald of the BC Wine Institute in Kelowna believes British Columbians will make the switch.

“British Columbian wine drinkers are savvy, smart, and willing to experiment,” he says. “They have proven that they are open to New World trends. They acknowledge tradition but they are willing to embrace change.”

Time will tell if he is right. Although screw caps are beginning to be mentioned in the same breath as cork, one of BC’s best known wine connoisseurs, the Pacific Palate’s Don Genova says, the ultimate decision to switch to screw tops will have to be made by the winemakers. “[Screw top] closures are really going to be the way to go in the future,” he says, “It should be a no-brainer for wineries. Why should they let so much of their wine be ruined by corks? Consumers will have to buy screw top wines because eventually the number of wines sealed by cork will drop to the point that screw tops will be more common than cork.”