The Problem with Corks
An interesting article, "Seal of Disapproval" on TizWine.com about corks, corked wines, and emerging trends with bottle closures. (Note: I can't find much who is running the site but it looks like they specialize in New Zealand wines and Industry News from "Down Under")
The article reports that,
Industry sources acknowledge that 2-3% of all bottles suffer from some cork-related problem. But last week's numbers exceeded 5% from a sampling of roughly 100 bottles. If you've been following the wine press of late, you'll have read that New Zealand is embracing screw caps for its quality wines to circumvent cork problems. On the other side of the argument, Prince Charles [advocates use of] traditional cork.
The author, Richard Best, affectionately refers to himself as the "Frugal Oenophile" explains,
Corks come from... the bark of the Quercus Suber oak tree. Corks come mainly from Portugal, where they are very big business. Cork manufacturers put the bark through rigorous processes in order to banish all forms of contamination before packaging the corks and shipping them to wineries around the globe. But the process is imperfect, as is the raw material. Problems still crop up, and virtually always ruin the wine as a result. And while better quality wines tend to have better quality corks, expensive wines are just as susceptible to problems as are the modestly priced.
He describes the 5 most common problems caused by corks:
Cork Problems
- Corky Wine
If a cork dries out, from storing the bottle upright for instance, it can impart a cork-like aroma to the wine. At its worst, it will allow enough air into the wine to cause further fermentation, which culminates in vinegar. A wine that is slightly corky may respond to a bit of aeration. If you encounter a corky wine, swirl some in a glass and see if the corky smell disappears. If it does, you can drink the wine after decanting it and allowing it to breathe for 15 minutes.
- Cork Taint (Corked)
A corky wine and a "corked" wine are not the same. A corked wine is one that has been affected by contaminants that were on the cork at bottling time. The contamination has reacted with compounds in the wine, producing a variety of off odours and flavours. A corked wine often smells like damp cardboard [or wet newspaper, sic] , but can also smell like mould or rotten wood. Sometimes it will show up as a musty aroma on the back palate. It's not always obvious when a wine is corked. Even experts have trouble spotting a mild case.
The main culprit behind cork taint is trichloroanisole, or TCA (a by-product of the chlorine that is sometimes used to clean corks), which reacts with substances in the wine. Other compounds can also cause cork problems but TCA gets most of the blame. Regardless of the cause, the final result is that a corked wine is ruined and should be returned as defective.
- Bottle Stink
Bottle stink manifests as stale aromas immediately upon opening, and is caused by compounds that are less damaging than those that cause cork taint. Bottle stink usually disappears shortly after the bottle is opened, especially with aeration.
- Mustiness
Musty aromas can be caused by bad corks and also by other problems at the winery. While the aroma may be less objectionable than cork taint, it will not go away and the wine will be unsalvageable.
- Mouldy Aromas
These aromas are caused by a mouldy cork and cause the wine to smell and taste mouldy. This wine, too, is ruined.
Fortunately, many of my home wines haven't had cork taint. For this year's harvest I plan to stick with my current cork manufacturer, Amorim. I may upgrade from a 15 grade to a 20 grade, which most commercial wineries use. I will stay with the 1.75 in. cork length. The 2 in corks are much more expensive and I believe aren't worth the money for the wines I make.