Tainted Tradition Versus Tainted Wine
Is there any sound more inviting than the squeak of the corkscrew and the cork pulled from a bottle of wine? In your dining room, it can stir impulses like a chocolate soufflé at the next table. What if that bottle happens to have a screw cap? Is that an affront to the charm and romance of the moment?
Proficient wine service is an art form, regardless of the closure. Look at the entire picture. Isn't a sommelier more than an opener of containers? Fine wine service is a combination of careful selection of wines on the list, subtlety educating and guiding the guest to the right bottle for their meal, and serving with grace and style.
Some restaurants take a stance against anything but natural cork, allowing not one bottle with a screw cap to grace their wine list based simply on aesthetics. One could argue that this is shortsighted, given that we did not enjoy the invention of the fork until the late 17th century.
Enter the Screw Cap
Why is there a movement toward a screw cap? One reason is the seemingly growing incidence of "cork taint," which changes the way a wine smells and tastes, and not for the better. A wine that suffers severely from a tainted cork has a dank, musty aroma which some liken to a cross between wet grass, rotten cardboard, old sneakers and damp laundry forgotten in the washing machine for a few days. Before we knew better, those in the wine business would wait for the taint to "blow off" or dissipate, but in fact it increases as it sits in the glass. You can usually, but not always, smell it on the cork and in the wine. The culprit is TCA or trichloroanisole, a chemical compound that can infect natural cork. (For more information, see "Climbing the TCA Learning Curve" on Page 43 of this issue.)
What About Plastic Corks?
Synthetic corks have improved greatly in the last several years. Screw-top proponents argue that the seal is not as good as either cork or screw caps. They also argue that synthetic corks can be difficult to extract from the bottle, and difficult to get back into the bottle. On the positive side, the synthetic cork addresses the concern over TCA, while somewhat overcoming the negative perception consumers might still harbor against screw caps. There are many wines using this closure. Bearing in mind the objections to plastic corks, these wines might be best for immediate enjoyment; i.e., you need to finish the bottle while you're at it. That said, if your staff is able to reseal the bottle adequately without undue strain, then this point might be moot.
The Origin of TCA
Tim Burvill, chief winemaker for Buckeley's in South Australia, weighs the risks of using natural cork, in light of its origin. "Cork taint is something that will always occur in natural corks," Burvill says. "Apparently, in Portugal (where most of the world's cork comes from) in the 1940s and '50s, they used some 'organo-chlorides' as herbicides in the cork plantations, to keep all the weeds, etc., from growing in the cork forests. These chemicals seeped into the groundwater, and have been taken up by the trees. Some micro-organisms present in the cork convert these chlorides into 2,4,6-trichloroanisole, which is commonly known as TCA or cork taint."
How Cork is Made
Natural cork is the bark from a species of oak called Quercus suber, grown predominantly in Portugal (the largest producer and processor of cork), but also in Spain, North Africa, and Tunisia. The structure of the bark is such that it has small, densely packed 14-sided cells that make it elastic and impermeable to gases and liquids. Portugal is the largest producer and processor of cork. Every nine years the bark is peeled from the tree. It takes about 40 years of harvesting before a single tree begins producing the dense high-quality corks that a winery demands. That bark is then dried for a year before the corks are drilled out.
The cork strips are then boiled to kill any molds and make it more flexible. To further disinfect the cork and add cosmetic appeal, the product is bathed in chlorine; however, most processors now use a hydrogen peroxide bath, as there is evidence that chlorine increases the likelihood of cork taint. After an additional three-week rest in the processing plant, the cork is sorted by grade -- the fewer the irregularities, the higher the grade. The corks are then stamped out at right angles to avoid any knotholes that could run directly through the length of the cork which would compromise its seal. Finally, the corks are further disinfected with sulfur dioxide or via irradiation, and bagged in plastic.
Another type of wine cork, the "agglomerate," is made from cork particles glued together. This was seen early on as a response to the TCA problem; however, it does not lower the incidence of cork taint. And, some tasters report a "gluey" aroma in wines with agglomerate corks.
The demand for cork-finished wines has increased dramatically in the last 25 years, as has the overall quality of wine increased. As more value-priced 750-milliliter bottles are produced to fill consumer demand, sales of jug wines and "bag in the box" generics have diminished. As a result there is more cork being used to bottle wine, and some of that cork is of questionable quality.
What Percentage of
This is a hotly debated point. In 2002, judging in the National Riesling Challenge in Canberra, Australia, revealed that more than 10 percent of corked wines suffered from TCA. In May of last year, at the International Wine Challenge in London, 4 percent of cork evaluated indicated TCA. Many Australian producers will place this figure at 6 percent to 12 percent, while the cork producers claim it's less than 1.2 percent. Another controversial survey overseen by the trade organization British Wine & Spirit Association found very low levels -- between 0.7 percent and 1.2 percent of TCA-affected wines; however, the methodology has been challenged in the wine industry as biased toward the interests of cork producers.
Cork Producers Weigh In
In my experience, retailers, sommeliers and wholesalers will typically claim that about 4 percent to 10 percent of the wine they open has a defect resulting from the cork. The big question is what is an acceptable "failure rate"? For example, would any fast-food chain accept that three in every 100 burgers have an "off" taste, and say "Well, we get it right 97 percent of the time"?
Cork producers, of course, defend their product. As would any industry, they attempted to sway popular opinion. One campaign questioned the quality of wines using plastic or screw tops. Another strategy questioned the environmental damage of plastic corks and metal tops littering the ecosystem.
Enter science. APCOR, the Portuguese Cork Association, which represents 80 percent of all cork exporters, has dedicated 2.5 million euros to commission independent research, with the goal of eradicating TCA.
In the fray of this debate, both demand and production of cork continues to increase. On the supply side, the cork forests are growing, not shrinking, with 370,000 acres of new cork forests planted in the last 20 years. Recently the Portuguese government placed the cork forests under a preservation order by requiring that a new tree be planted for every one felled. On the demand side, for example, the Modesto, California, winery of Ernest and Julio Gallo now uses tens of millions of corks, as opposed to a decade ago, when they dominated the screw-top wine market.
Airing Out the Differences
Conventional wisdom among wine experts is that natural cork keeps wine from oxidizing, while allowing a small amount of transference to air, which ages the wine properly. Today, winemakers who deal with the decline in quality cork are challenging this assumption, and the debate ensues, particularly over red wines.
"The [screw cap] also eliminates the very slow and minute permeation of oxygen into the wine, which happens with natural cork," Tim Burvill says. "This is fantastic news for aromatic white varieties such as Sauvignon Blanc and Riesling, and nearly all producers of these wines in Australia and New Zealand are switching to [screw caps] for sales in Australia." Advocates argue that this method helps wines retain their freshness and fruit flavors.
Jeffrey Grosset, a vintner who is well-regarded for his Riesling, Sauvignon Blanc, Pinot Noir and a red blend, Gaia, bottles 95 percent of his production with screw caps. "Even a failure rate [caused by TCA] of 1 percent is unacceptable," Grosset says.
There is some difference of opinion here on the appropriateness of red wines with such a closure. Grosset has no qualms about his Pinot Noir and red blend under screw caps. He cites expert opinions, including noted wine author Emil Peynaud and researchers at the department of viticulture and enology (grape growing and winemaking science) at the University of California, Davis. Researchers there conclude that "all the known positive attributes of wine aging occur in the absence of oxygen."
Burvill sees it from another perspective, based on his experience and preference for his reds. He believes that using natural cork on certain varieties encourages "tannin polymerization" (i.e., in the presence of oxygen, tannin chains join together, and eventually become so large that they fall out of solution). "This creates a softening effect in red wines that occurs with aging," Burvill says, adding, "Time will tell."
Reducing the Odds of TCA
So, what do winemakers like Burvill do to reduce the statistical odds of TCA-infected corks? First, they seek the best possible source of high-grade cork. Upon arrival to the winery, thousands of bagged corks are kept separate from the cellar, to prevent any potential contamination with wine in barrel. Ideally corks should be stored in a ventilated room with a temperature of 59-68 degrees Fahrenheit (15-20 degrees Celsius), and a humidity level of 50 percent to 70 percent. Random samples are taken from each bag and placed into a base wine. The samples are then evaluated. If the percentage of cork taint is such that the winemaker feels it will be too great a risk, the shipment is returned to the cork supplier.
Growing Consumer Acceptance
Producers in Australia and New Zealand have led the charge to a metal closure. Entire regions, such as Australia's Clare Valley where Riesling is king, have gone the screw-cap route. Corporate giants like Southcorp who represent Rosemount and Penfolds, among others, are reputed to be working aggressively on alternatives to natural cork.
Germany is also taking the initiative with top producers such as Gunderloch Estate in the Rheinhessen, with their 2002 Jean Baptiste Kabinett, which sports a screw cap. This wine has been received with "overwhelmingly positive" response from consumers, according to Mark Huebner, national sales director for Rudi Wiests' Cellars International, who imports some of the finest German estates. Huebner says that his company is encouraging its producers to use the new closure on entry-level wines such as Qba and Kabinett, which are typically enjoyed upon release.
And in the United States, the move is on to sway consumers to screw tops. Boutique wineries like Plumpjack and the gifted and highly entertaining Randall Grahm of Bonny Doon Vineyards have raised some awareness, if not a few eyebrows. Last October, Grahm and entourage paraded a coffin through New York's Grand Central Station en route to an all-black dinner to mark the "death" of the cork. Master of Wine Jancis Robinson presented the eulogy for Thierry Bouchon (Tire-bouchon is French for corkscrew). Robinson says that "fewer than 30 percent of households in the United States own up to owning a corkscrew." The dinner, complete with black squid ink risotto, black mole roasted venison and 33 wines, ensued.
How your guests feel about wines under a screw cap or synthetic cork will be partly determined by your acceptance of them, and how you train your staff to present them. Consumer acceptance of nontraditional closures will not be an overnight phenomenon, especially among those whose only memory of screw caps is from inexpensive varieties of choice, drank
under high school bleachers during their misspent youth. If a diner turns up his or her nose at a screw-capped bottle, you now can tell the story of cork taint. Your challenge is to keep the romance of wine alive in your restaurant, regardless of cork, plastic or metal closures.
Climbing the TCA Learning Curve