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Corks have significant impact on wine

Ron Smith, World of Wine columnist

Making wine — the growing of the crop, the fermentation process, aging in barrels, bottling and sealing — is a study in proper sequential science. Blow it somewhere along these lines, and the winemaker could be out of business quickly.

Dr. Paulo Lopes, research and development manager at Amorim Cork, has found that with proper temperature and humidity control, wine can be stored upright with no ill effects.

Specifically, he found that storing sparkling wine should always be upright, not on its side. His research has shown no difference in the oxygen levels found in wines that have been stored horizontally or vertically.

Oxygen in bottled wines comes from the cork itself rather than diffusing through the cork from the surrounding environment. Air trapped in the lenticels (natural pores) of the cork slowly diffuses into the wine over a period of about 3 years.

The quality of the cork used in bottling affects the oxygen diffusion: Longer, grade A corks with fewer or more homogenous lenticels will release less oxygen.

As time passes everything eventually deteriorates, and wine corks are no exception. After about 25 years wine corks begin to lose elasticity and will start to allow atmospheric air into the bottle along their sides.

If stored in contact with the wine, it will absorb about 3 millimeters (0.118 inches) of wine. Lopes states that it is the temperature and humidity that has the ultimate impact on the lifespan of the cork, with 68 degrees F (20 degrees Celsius) and 50 percent humidity being the ideal. At higher temperatures, the cork will eventually dry out.

With sparkling wines, corks absorb both liquid and gas as they pull carbon dioxide from the wine. Corks are straight before they are put into the bottle; the mushroom shape is a result of the inserted portion being compressed in the bottle and coming into contact with the wine. Upon being extracted, the lower portion of that natural cork continues to expand and takes on the mushroom shape.

Andrew Waterhouse, professor of wine chemistry at the University of California, Davis, has found that a sheet of polyethylene plastic wrap can 'rescue' a bottle of wine with 'cork taint' (TCA molecules give wine a wet dog or moldy newspaper smell).

Carefully pour the tainted wine into a plastic wrapped bowl. The 2,4,6 trichloroanisole — TCA — will attach to the plastic, with the process taking only a few moments. The 'de-tainted' wine can then be poured back into a decanter to enjoy without the negative aromas.

The French company Embag markets a product called "Dream Taste" which uses a copolymer shaped like a grape cluster to remove the TCA taint from wine.

What is the "average" wine drinker to do if ideal temp and humidity cannot be maintained?

I suggest drinking it within a year or two, of course.

Ron Smith, a retired NDSU Extension horticulturist, writes weekly about his love of wine and its history. Readers can reach him at tuftruck1@gmail.com.