That said, misguided hygiene practices have historically been part of the cork-taint problem. Cleaning using chlorinated bleach was common in wineries until a link to cork taint was found.
Contact between barrels and bleach on cellar floors was a particular pathway for TCA to strike. In the s many wineries in France in particular were plagued by treated wood in renovated cellars.
Flame-retardant paints and fungicides were found to taint wine with TBA. Barrelled wines were particularly badly hit, and some facilities had to be rebuilt. Nowadays most wineries know to avoid chemicals containing tribromophenols. Heat-treated wood is more common, and barrels are rarely cleaned with chlorine.
Barrels contaminated during production remain a problem - the scale is unclear, though the potential for systemic occurrence is high. To combat the problem, one cooperage in Chile has recently pioneered the use of trained dogs to sniff out harmful compounds.
Rubber is particularly vulnerable. Bentonite, a clay preparation used for fining, also has a high affinity for TCA, and will absorb it and other chemicals from the atmosphere. Systemic TCA may well impart a trace level parts per trillion of taint to wine, which is not detectable by most drinkers. However it can then amplify low levels of TCA in a cork to a point above the typical sensory threshold around ppt.
Systemic TCA can therefore potentially affect a wide range of products. I have been told stories of wine professionals sending back draft beer because they detected TCA spoilage. The incidence of cork taint has long been a topic of fierce debate. Figures seem to vary depending on which side of the issue they originate. The cork industry tends to estimate the cork failure rate at percent around one in 60 bottles. In the mid s non-cork industry estimates tended to put the figure at around percent.
In any other industry this would certainly be an unacceptable failure rate. In "Flawless" his book on wine faults , Jamie Goode outlines various anecdotes from wine competitions or magazine tastings recording failure rates.
The picture is obscured somewhat by false positives or misdiagnosis. The most rigorously tested data may come from the Australian Wine Research Institute. This was produced during three sessions of their Advanced Wine Assessment Course for potential wine show judges. They used gas chromatography to test all wines regarded by at least 15 percent of tasters as being TCA-affected. Though the sample was possibly skewed somewhat in favour of higher priced bottles with more expensive corks, the failure rate for TCA among wines tasted was 6.
Between and , their Commercial Services unit tested over wines for musty taints. It should be noted that increased screwcap usage could serve to emphasize the incidence of systemic causes of taint.
Many commentators felt that cork taint increased in frequency in the s and early '90s. This was often put down to instability in the cork industry, and the abandonment of traditional forestry practices, following the Portuguese Revolution in A sharp rise in demand in the s may have had a negative impact on quality.
However, various attempts have been made to improve corks in recent years, to the point where some commentators feel it will be largely eliminated by Consumers should not forget that this applies to new bottling runs, so the wet-cardboard smell will linger for some time after this.
The wine industry in general including cork producers has largely moved away from chlorine-based cleaning products. The former have also instituted a range of other improvements in the way they manufacture, store and ship corks. Complete prevention of TCA has not yet been achieved. But cork can be treated with microwaves, and molds can be extracted using hypercritical carbon dioxide. Testing is where the big advances have been made.
Barks can be tested for the presence of molds before corks are made. And as Lisa Zimmerman reported last year , Portuguese cork giant Amorim has developed a gas chromatography technique NDtech to quantify trace levels of TCA in natural corks in a matter of seconds.
Previously such processes took precious minutes and so were not commercially viable. There is an ongoing debate regarding whether composite corks are more or less susceptible to cork taint.
The manufacturer DIAM confidently proclaim that they sell "consistent cork closures with no cork taint". This seems to be due to their patented "de-aromatization" processes including hypercritical CO2 , allied to a greater homogeneity compared to natural corks.
On the other hand, some accounts suggest high rates of taint in wines stoppered with agglomerated and colmated corks. These are made with granulated byproducts of natural cork production, which are bound together using pressure and adhesives. Colmated corks add cork dust to fill the gaps between granules.
One theory put forward suggests that a small amount of affected material would be distributed among a higher number of stoppers during the production process.
All that having been said, it is worth noting that TCA will not be harmful to human health in the sort of levels found in even a heavily corked wine. While Shafer runs an extremely clean cellar, making TCA an infrequent issue, the goal for more than two decades has been percent eradication.
TCA is a compound that is most at home in porous organic substances such as wood, cork, and cardboard — materials that are found in abundance in the traditional wine cellar. One of first things to go was the use of wooden pallets for storage. Shafer uses plastic pallets throughout the facility. In addition, in the cellar all the wooden barrel racks were replaced with stainless steel and the wedges used to hold barrels in place were replaced with new ones made from aluminum.
Because TCA is a compound formed in the presence of chlorine, the winery also stopped using chlorinated water and found new ways to sterilize tanks and equipment. We've received your email address, and soon you will start getting exclusive offers and news from Wine Enthusiast. Humans have a remarkable sensitivity to cork taint, with people able to smell TCA between two and five parts per trillion, and some even below one part. Cork taint inhibits olfactory signal transduction, creating a muting effect.
Simply put, it interferes with your ability to smell. Heavy cork taint gives off an unpleasant aroma reminiscent of a musty basement. In lesser amounts, however, TCA can simply blunt aromas and flavors, making a wine seem muted and uninteresting. Recent research indicates that TCA itself has no smell, but it appears to suppress olfaction in such a way that presents as dull or moldy odors. However, TCA itself has no harmful effect on humans, other than ruining your wine.
TCA is quite stable over time, whereas other aroma compounds are not. This means cork taint can become more prominent as a wine opens up or as a bottle ages. It also means cork-tainted bottles may not show obvious fault. In blind tastings for Wine Enthusiast , between 3. With 30 billion bottles of wines produced per year closed by cork, this equates to an estimated one billion bottles ruined by TCA annually.
If you are drinking one bottle of wine per day, assuming they are all closed with natural corks, you would expect to have 7—22 corked bottles of wine per year.
There is a misconception that wines are more likely to be cork tainted if they are less expensive. The line of thought is that cheaper wine uses less expensive, and therefore inferior quality, cork. Until the day when all natural corks can be reliably and individually tested for TCA and other musty compounds, winemakers and drinkers will have to contend with cork taint. The best thing you can do as a consumer is learn how to reliably recognize it. The best way is to start by smelling the wet end of the cork every time you open a bottle.
Look for a faint or strong musty aroma. Then smell the wine and look for the same. The more you practice detecting cork taint, the more sensitive you will become to it. Soon you will start to perceive more subtle contaminations. Wine fault kits that include TCA can also be purchased. Keep in mind, however, that these will have a very strong presentation. You may have had cork-tainted wine and not even noticed. Individual sensitivity to cork taint varies quite widely, with some people able to smell TCA below one part per trillion and others unable to smell it at times that amount.
0コメント