Cork breathability unplugged

13 June, 2008

I have read your article that appeared recently in Off Licence News concerning the breathing of corks during the post-bottling period (What's Your Problem, April 18). I tend to agree with you on the controversy of the issue, but I do not share your opinion that wine bottle ageing occurs under complete asphyxia.

In our research at the Faculty of Oenology of Bordeaux we have clearly demonstrated that there is a micro-oxygenation of bottled wine sealed with corks and that most of this oxygen is provide by the cork cell structure.

The oxygen transmission rates (OTR) provided by corks are very small, but measurable. This tiny oxygenation would appear to be positive for wine ageing and avoids the formation of post-bottling reductive flavours, which are more noticeable in wines sealed with tighter closures, such as screwcaps.

On the other hand, the OTR provided by synthetic closures resulted in wines with a tendency to lose fruit attributes and develop oxidi sed, "wet wool" and toasty aromas prematurely.

The evidence that some micro-oxygenation takes place during the post-bottling period is not new. Jean Ribéreau-Gayon in 1933 was the first to report a permeability of natural cork stoppers: from 0.10 to 0.38ml of oxygen over the first three weeks and between 0 to 0.07ml over the four following months. Furthermore, you can always detect tiny amounts of oxygen (measured by polarographic probe) in very old bottles sealed with corks.

In conclusion, it's clear that well-balanced wine bottle ageing never takes place under strong aerated or completely anaerobic conditions, but rather under the "poor-oxygen atmosphere" that cork stoppers are able to provide in a very slow rate over time.

Paulo Lopes

Wine and packaging scientist

Amorim Cork Research, Mozelos, Portugal

Please God, deliver us from the root of all evil: off-trade bashers

I went to church last Sunday and was surprised to hear the vicar mention binge-drinking during a sermon about showing mercy. He went on to imply that supermarkets and off-licences, by selling drink cheaply, were not being "merciful" or showing as much care as they should towards customers with binge-drinking problems.

Isn't it a terrible state of affairs when even the liberal Church of England has started blaming us retailers for what is certainly a cultural problem? What happened to church youth clubs keeping kids off the streets so they have something better to do than hang around on street corners drinking white cider?

And isn't it about time someone stood up for the off-trade in general and defended us against the tidal wave of blame for Britain's boozing that is being hyped, unsubstantiated, from the government, the media and now the pulpit?

Caroline Parkinson


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