Uncorked

Cork tree quality, its impact on wine

Who would think climate change could influence the wine we drink?

Beyond enjoying a glass during a discussion on the topic, climate change and wine are not often subjects that go hand in hand. But climate change and its influence on the wine industry are affecting the wines we drink in numerous ways.

The climate discussion has recently focused not only on grape growing but also on another important element of wine: the cork.

Natural wine corks are made from the bark of the Quercus suber trees, also known as the cork oak. The trees are prevalent in northwest Africa and southwest Europe. A study published by the University of Lisbon offers insight into changes in the cork tree they believe may be linked to climate.

In recent years the trees have produced lower quality cork and the cork bark is thinning. Researchers analyzed genes in the bark of high quality and low quality cork trees in Portugal and discovered what they referred to as "heat shock proteins." These proteins are essential in helping the higher performing trees withstand environmental stresses such as drought and temperature spikes. The proteins also promote cell division, which makes the bark grow thicker.

The low yielding trees had lower levels of the shock proteins and other mutations that led researchers to conclude the low-quality trees are adversely adapting in response to environmental pressures.

It's an important finding because not only are the trees producing thinner bark (which can't be used for premium corks), the cork had many more "lenticular channels" (small airways allowing a gas exchange between the cork and the outside air). Such channels are undesirable in wine corks because they let oxygen through. The alcohol in the wine reacts to the oxygen exposure by taking on a sour taste.

There's talk in research circles of cloning to offer the trees genetic resistance, modifying them to produce more heat shock proteins. The modification is a viable solution, but it could take years to positively affect the wine industry, considering an average cork tree needs to be 25 years old before it can produce a consistent annual harvest.

And so the great cork debate continues.

Lorri Hambuchen is a member of London's Institute of Wines and Spirits. Contact her at the Arkansas Democrat-Gazette, P.O. Box 2221, Little Rock, Ark. 72203, or email:

uncorked@thewinectr.com

Food on 09/10/2014

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