Monday, September 11, 2006

About "Cork-Taint" and Plastic

So why was boxed wine preferred 2 to 1 over cork-finished bottles in a blind tasting by a group with very refine palates (see the previous post)? And why was wine in screw-cap finished bottles slightly preferred?

"Cork-taint" is an issue that has been getting plenty of discussion lately, as synthetic corks have been making their way into the market. The synthetic corks are a good way to reduce the risk of taint. But the truth is that natural cork is not the only source of taint. The flavor of "taint" comes from a chemical called TCA. And the TCA can be present in the wine before it even goes into the bottle. The presence of TCA may be perceptable to the trained palate at levels as low as 1 ppt, and the acceptable threshold may vary by the wine, and the individual taster.

An excellent article in the 12/01/2003 edition of Wine Business Monthtly discusses taint, what it is, where it comes from, and suggests to me an answer to the question with which I started this post. Find the article at

Some high points:

The chemical 2,4,6-trichloroanisole (TCA) is produced by the metabolism of trichlorophenol (TCP) by a broad range of molds. These molds are pervasive and ubiquitous. They can grow in and on any wood or paper product. Like most fungi, they require a fairly moist environment like a winery.

Now here's the kicker:

...plastic absorbs TCA, though the TTB does not permit putting plastic into wine to remove it (it does allow bag-in-the-box containers). Even the plastic liners on screwcaps can absorb TCA.

So, if there are low levels of TCA in a wine before packaging, possibly bag-in-box packaging reduces the concentration of TCA in wine by absorption into the plastic. And the same thing may be happening to a lesser degree in wines finished with screwcaps. This could explain why boxed wine would be preferred 2 to 1over cork-finished, and screwcapped wine preferred to a lesser degree. And this make a case for storing all bottled wines lying on their sides, even those finished under screwcaps and synthetic corks .

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