Cork taint is a broad term that refers to a wine mist which is characterized by a set of unwanted odors or flavors found in a bottle of wine, especially decay that can only be detected after bottling, aging and opening. Although modern studies have shown that other factors can also be responsible for stains - including wooden barrels, storage conditions and transport of corks and grapes - cork plugs are usually considered responsible, and wine found tainted at the opening is said to be "corked" or "corky ". Cork stains can affect wine regardless of price and quality level.
The main cause of cork is the presence of 2,4,6-trichloroanisole (TCA) or 2,4,6-tribromoanisole (TBA) compounds in wine, which in many cases will be removed from cork, but which can also be transferred through the cork instead of. TCA is a compound that does not occur naturally. This is made when some fungi are treated with chlorinated phenolic compounds, which are the types of antimicrobial agents used in wood processing. This compound is one of the major factors responsible for the problems associated with molds that may be found in cork. A very small amount of this compound, in the order of the nanogram, can be responsible for this defect. Tailed wine containing TCA has a distinctive odor, variously described as resembling a moldy newspaper, wet dog, damp cloth, or a damp basement. In almost all cases the wine that is clogged with the original aroma of wine is significantly reduced, and the highly polluted wines are very unpleasant, though harmless. While the human threshold for detecting TCA is measured in parts of one digit per trillion, this can vary with some of its large order depending on the sensitivity of the individual. Detection is also complicated by the habituation of a very rapid olfactory system for TCA, making the odors less obvious in each subsequent sniff.
Video Cork taint
Production
The production of TCA in corks or its transfer by other means into wine is complex, but most of the results when natural air fungi are presented with chlorophenol compounds, which they then convert into chlorinated anisole derivatives. Chlorophenols taken by cork trees are industrial polluters found in many pesticides and wood preservatives, which may mean that the incidence of cork stains has increased in modern times. Chlorophenols can also be a product of the chlorine bleaching process used to sterilize cork (not used anymore); this has led to increased adoption of methods such as peroxide bleaching.
TCA and TBA are responsible for most cases of cork stains, but other less common and less known compounds that may cause different varieties include guaiacol, geosmin, 2-methylisoborneol (MIB), octane-3-ol and also octene-3 - one - each having its own aroma, all of which are considered inappropriate in wine.
Maps Cork taint
Estimated occurrence and industry response
The cork-industry group APCOR cites a study that shows a 0.7-1.2% stain level. In a 2005 study of 2,800 bottles sampled at the Wine Spectator blind-tasting facility in Napa, California, 7% of the bottles were found stained.
In 2013, the Cork Quality Board runs over 25,000 tests. The result, compared with data from eight years ago, showed a sharp decline in the TCA level, about 81 percent. In the last test, 90 percent of natural cork sample delivery samples showed values ​​below 1.0 ppt and only 7 percent showed a result of 1.0-2.0 ppt.
Improvements in the methodology of cork and wine making continue to strive to reduce incidents, but the media attention given to cork blockers has created controversy within the winemaking community, with traditional cork farmers on one side and makers of new synthetic closures and screw caps on the other. Threaded screws and synthetic corks, however, are considered vulnerable to other stain spots: sulfidation. This may arise from a decrease in oxygen supply that concentrates the sulfurous odor arising from grapes with universal preservatives, but most likely this wine contains an excessive amount of sulfite-based preservatives to start.
Systemic TCA
TCA systemic contamination occurs when TCA has infiltrated the wine in a way other than cork and can affect the entire production of wine, not just a few bottles. This happens when wine vats, drain pipes, logs in cellars, or rubber hoses are tainted by TCA. Sometimes the entire basement has to be rebuilt to extinguish all the potential causes of systemic TCA. Rubber or gasket hoses have a high affinity for TCA and therefore concentrate TCA from the atmosphere. The wine or water that then passes through the infected tube may become contaminated with TCA. Another possible way of TCA contamination is through the use of Bentonite, a clay preparation used in treating grapes for heat stability. Bentonite has a high affinity for TCA and will absorb TCA and related chemicals in the atmosphere. If the open pouch of Bentonite is stored in an environment with a high TCA concentration (1-2 ng/g or ppb), this TCA will be absorbed in Bentonite and transferred to the wine where Bentonit is added.
It should be noted that this systemic TCA often gives traces (1-2 ng/L or ppt) to wine, which itself is undetectable by most consumers. However, with a high TCA base level in wine bottles, even the additional contribution of a relatively clean cork can increase TCA levels in wine above the threshold (4-6 ng/L or ppt), rendering wine "corked."
The main chemical precursors to TCA are TCP (2,4,6-Trichlorophenol), an anti-microbial agent used in wood processing. Mushrooms (and some suspected bacteria such as Streptomyces) can detoxify TCP by methylating -OH to -OCH 3 , which is non-toxic. Chlorinated phenols can form chemically when hypochlorite acid (HOCl-, one of the active forms of chlorine) or chlorine radicals in contact with untreated wood (such as barrels or pallets.) The use of chlorine or other halogen-based cleaning agents is being removed from the industry wine by peroxide or peracetic acid preparation. Chlorine dioxide has not been proven to produce this spontaneous chlorophenol. Chlorine dioxide is a relatively new agent used in the wine industry because of its obvious advantages, pure chlorine dioxide shows no evidence of possibility for TCA to be made. Wine Spectator has reported that California wineries like Pillar Rock Vineyard, Beaulieu Vineyard, and E & amp; J Gallo Winery has a problem with Systemic TCA.
Treatment
Current filtration and purification systems are trying to remove TCA from clogged wine to make it drinkable again, although there are several ways to reduce TCA levels in TTB approved wine (previously BATF).
One method to remove TCA from contaminated wine is by soaking polyethylene (a plastic used for applications such as milk containers and plastic food wrappers) in the affected wine. Non-polar TCA molecules have a high affinity for polyethylene molecules, thus removing stains from grapes. The polyethylene surface area required to reduce the stain to sub-threshold level is based on the level of TCA in the affected wine, temperature, and alcohol level of the grape.
This can be done at home, as advocated by Andrew Waterhouse, professor of wine chemistry at the University of California, Davis, by pouring wine into a bowl with a polyethylene plastic sheet. For ease of pouring, pitchers, measuring cups, or bottles can be used instead. 2,4,6-trichloroanisol will be attached to the plastic. This process is effective within minutes.
Some vintners have used so-called half and half mixed to remove TCA from grapes (TCA in wine is alienated by butter fat in half and half ).
The French company Embag markets a product called "Dream of Flavor" which uses copolymers shaped like a bunch of grapes to remove TCA stains from wine.
See also
- Alternate wine closure
- Flavor scalping
- The wine issue
Note
References
External links
- "The four most common flaws and how to detect them", New York Magazine
Source of the article : Wikipedia
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