Testimonials |
It is well established in the wine industry that oxygen plays a critical role in the development of wine from the beginning of the winemaking process through the time the wine is consumed. The presence of oxygen directly impacts how each wine develops both chemically and in terms of its sensory attributes as experienced in aroma, taste, structure, and color.
Although the industry has become aware of the importance of oxygen management during the winemaking process, the ability to monitor and control oxygen is very limited. In addition, the impact of oxygen during and after the bottling process, and the role of the closure in post-bottling wine development is less understood.
It is clear, however, that a significant percentage of wine is negatively impacted by oxygen mis-management, resulting in wine faults which can be traced directly to the closure as well as the winemaking process. During the most recent International Wine Challenge 2008, thousands of wines were evaluated by worldwide experts during blind testing. Approximately 6% of all of the wines tested were judged faulty. Of the faulty wines, 31% were the result of cork taint, 29% were due to reduction, and 19% were due to oxidation. Cork taint remains the largest category of wine fault, occurring in wines closed with natural, technical, or agglomerated closures. (Cork taint is recognizable by a moldy odor caused by interaction of the wine with a fungus.)
However, almost 50% of the faults in the IWC testing are due to reduction and oxidation which are the result of oxygen mis-management. Reduction which results from too little oxygen being present during winemaking and aging, increases the presence of unfavorable sulfur based components that cause an odor of rotten eggs. Certain varietals and winemaking styles are more susceptible to reduction and closures that allow minimal oxygen ingress such as screw caps are suspected of increasing the potential for this undesirable condition to occur. Oxidation occurs when too much oxygen is present in the wine, contributing to the development of muted or off-aromas and discoloration. Oxidation is most often the result of the introduction of too much oxygen during the winemaking process, particularly if bottling is poorly controlled. Closures that do not form a tight seal or have structure inconsistencies such as natural cork are often the cause.
Closures contribute to the management of oxygen in wine both during and after the bottling process. During bottling, the rapid recovery of inserted closures (recovery from compression during the corking process) prevents atmospheric oxygen from rushing into the bottle. A tight seal between the closure and the inside surface of the bottle neck prevents both wine leakage during bottle inversion and further oxygen ingress between the closure and the bottle neck. After bottling is completed, the closure prevents potential leakage and oxygen ingress during high temperature fluctuations that might occur during transportation or extended storage after the bottle leaves the winery.
Once the bottle neck is tightly sealed, oxygen can still enter the bottle through the center of the closure in what is referred to as oxygen transfer rate (OTR).
