I’ve been putting off this article for a month now. I think it is time I just bite the bullet and write it. It is much more fun to write about the last wine we discovered than to talk about problems. But it is part of what we are learning and therefore legitimate fodder for the blog.
Going into the wine store and selecting a wine, I still get the willies when I see a screw cap. I immediately think of Thunderbird, Annie Green Springs and Boones Farm. When I see a screw cap, it better have a jug wine under it, not my $23.00 bottle of Pinot Grigio!
Well, this is not the point. Producers are starting to push back against tainted wine. Wine drinkers are becoming more sophisticated and with today’s open communication lines, they are being less intimidated than in the past. “What if I complain to the sommelier about this wine and look like a fool?” Well, what if it isn’t earthy mushroom but wet cardboard and newspapers you smell? You may have a “corked” bottle. A bottle tainted with TCA (trichloroanisole).
TCA is a chemical produced by mold growing in a tainted cork. It is totally harmless, but it is detectable in one part per trillion! To put that in perspective, that is one drop of TCA for every 1,000,000,000,000 drops of wine. Most folks cannot detect this low of a level, but can detect 10 ppt. (In order to give you a sense of one part per trillion, this is like having your first name spoken once for one second in 43,000 years and you being able to hear it.)
In one case, TCA was blamed for an off-flavor component in eggs and broiler chickens. In that case, the chemical appears to have originated as a contaminant in feed and litter that was transformed to 2,4,6-TCA through microbial action. In the case of cork taint, it is presumed that 2,4,6-TCA originates from the chlorination of lignin [a wood component]-related compounds during chlorine bleaching in the processing of cork. (1 )
TCA poses no harm to humans, however it is the ruin of many a bottle. The cork industry will say that 7 in 1000 corks will foul a wine bottle, but the wine industry has claims as 1 in 10 bottles show some signs of being corked.
Wine Spectator reports the number typically ranges from 1 percent to 15 percent of all wines, depending on whether it comes from closure manufacturers, vintners or another source. Wine Spectator's Napa office tracks the number of "corky" bottles in tastings of California wines, and the percentage of defective corks routinely runs at 15 percent. At the magazine's California Wine Experience in 2004, the team of sommeliers who screened the wines for the seminars reported that the occurrence of “corky” bottles was 4 percent to 12 percent. The cork industry has a different estimate of cork failure: typically 1 percent to 2 percent.
TCA most frequently occurs in natural corks and is transferred to the wine in bottle from the cork closure. Other sources are pressure treated wood products and interaction with chlorinated chemicals. These non-cork generated TCA sources can find their way into vats, bottling equipment and through corks during aging. If a complete lot is contaminated, it is most likely the winery is contaminated, and that can spell disaster for the winery.
The presence of these compounds in cork can be associated with their use as wood preservatives and pesticides or with the use of chlorinated derivatives, commonly used as disinfectants of water, equipment, and work areas. Wineries must be constantly on the alert or a whole production lot could be lost. In order to eliminate whole lot contamination, wineries must rid themselves of pressure treated lumber products, some paints and sources of chlorine. Its sounds simple, but just try that in your home. This is why it is important to know your cellar contractor and know what materials are being used.
Mold Wars could be a solution?
There may be a biological solution to the problem. The use of Chrysonilia sitophila (a particular strain of mold) in cork stopper manufacture was studied and a simulation of the industrial processing of cork stoppers was performed. C. sitophila does not produce 2,4,6-trichloroanisole, guaiacol, or 1-octene-3-ol on cork slabs incubated for 66 days.(2) This approach is similar to using a dominate yeast in a fermentation or in the production of cheese.
There have been strides made by the cork industry, but we are seeing new types of closures come to the market place. Synthetic corks or Stelvin closures and screw caps are taking the lead in alternative closures.
The Stelvin closure can be engineered for optimal oxygen permeation, but may impart a chemical taste to the wine. The Stelvin closures also do not degrade in the environment, meaning that we will see them washing up on the beaches in the near future. Screw caps have been around for a while, but are resisted by consumers.
Engineering a closure for wine does have its challenges. Screw caps work well for Seven Up. You are not aging Coca-Cola. We do not know what will be the result of aging Bordeaux style wines with screw caps.
We just purchased a Ruffino 2005 Pinot Grigio and a Ruffino 2006 Pinot Grigio. The 2005 came with a composite cork, the 2006 with a screw cap. It is coming, maybe faster than we may want.
I’m sad, say it ain’t so. There is something that I like about opening a bottle of wine, the anticipation. Will the cork break? Will it be everything I hoped for? Were my instincts right? Will it go with dinner? Will Taster B like it? And the soft pop of the cork as it is pulled out of the bottle. The wine goes into the glass and the first swirl and sniff…ah, it’s going to be a good bottle.
It just ain’t going to be the same with a screw cap. Sometimes I wonder if I’m just being neurotic? And what about our children? Will they ever know the joy of popping open a good bottle of wine or will they think I’m being an old fart messing around with “Old Reliable?”
Will they ever hear the pop of a real cork or just tick-snap-snap-tick?
(1) Science News 121.25 (19 June 1982): 409-409. EBSCO.
(2) Role of Chrysonilia sitophila in the quality of cork stoppers for sealing wine bottles, Pereira, et. al., Journal of Industrial Microbiology & Biotechnology (2000) 24, 256–261. EBSCO.