| CORK TAINT can most accurately be described as "moldy" or "musty" or "earthy" or sometimes "medicinal" smell that masks or dominates the fruit aroma of wine and reduces the overall wine quality. The source may be one or more particular chemical compounds formed by a reaction between molds and chemicals. Infected wines are said to be "corked" or "corky" and the contaminant often referred to as "cork taint", although there are many other possible sources besides corks for its presence in wine. Molds may be originally present in raw cork bark or in wood used for barrels or barrel racks, tanks, scaffolding, walls, stairs, pallets, cardboard boxes, or other many other types of winery equipment or facilities. TCA can also can infect cork or wood that is in storage. Ironically, chemicals used for keeping the production environment sterile and safe from contmination become degraded by fungi or molds indigenous to wood products. The main culprit is thought to be chlorine bleach used in cork processing and also as a routine disinfectant in wineries. Common treatments such as insecticides, pesticides, herbicides, or flame-retardants, although no longer used on vines or even legal in some cases are also identified sources. Another possibility is atmospheric pollution by off-gassing from plastic equipment, or simply from old wooden buildings that have absorbed any of these chemical pollutants over time.
Regardless of the source or chemical identity, Cork Taint can impart a very unpleasant smell that, depending upon its severity, tends to dominate all other aroma characteristics of any wine it contaminates. The least offensive and most subtle sign of TCA is wine that has very little aroma at all. The Australian Wine Research Institute conducted experiments in early 2003, that demonstrated even a very low level of contamination, as little as one or two nanograms per litre, suppresses positive fruit aroma character in wine by as much as 50%. As with all aromas, individuals vary in their threshold ability to detect the presence and strength of Cork Taint, as well as their tolerance for it; experience can increase sensitivity. The human threshold for detection is generally considered to be above 5 nanograms per litre. Damage to the wine industry annually from Cork Taint is estimated to be $10-billion worldwide. A reliable process has been developed to detect and remove TCA from wine before it is bottled. While TCA can be detected in corks, however, there is of yet no proven method to remove it from this source. This presents both a complex challenge to wine science and mutual frustrations to the wine and cork industries. Experiments are ongoing to prevent or purge TCA from corks, using alternative chemical treatments, steam, gas emersion, microwaving, etc. For a more detailed explanation of TCA-related wine spoilage, see Cork Taint: TCA and Related Compounds, a web project of Professor Andrew Waterhouse's Students of Natural Products of Wine at the University of California at Davis. In terms of providing a thorough explanation of wine chemistry that can be easily understood by a layman, this is one of the very best articles on the Internet. Page created September 25, 2002; updated September 5, 2008 Except as noted, site design & content © 1999-2006 by Jim LaMar . All rights reserved. |
