How many wine lovers, I wonder, in their anticipation, appreciation and assimilation of this glorious liquid, give any thought to the importance of two very necessary prerequisites to their enjoyment – the bottle and the cork. Without them the modern wine industry would be very different, much less profitable and infinitely less gratifying.

Cork has been used as a stopper for wine containers as far back as the 5^th century BCE, although other sealants such as pitch, gypsum, sealing wax, pine resin or a coating of olive oil floating on top of the wine were the more popular methods. Indeed the use of corks seems to have vanished by the Middle Ages, and even up until the early 1600s the preferred method was an oil-soaked cloth or strip of leather stuck into the neck of the bottle.

Cork came into its own along with the production of uniform glass bottles in the 17^th century. Suddenly wine could be shipped and stored much more easily and with much less spoilage. And a further important development – quality wine could now be aged.

So where does this little giant of the wine world – cork – come from, and how is it produced?

Over half the world’s cork is produced in Portugal and Spain and comes from the outer bark of Quercus suber – the evergreen cork oak tree. Cork production is sustainable because it does not involve the death of the tree. The tree itself can live to be over 200 years old, although it must be 25 years old before cork can be removed from it. Even then it does not produce quality cork suitable for wine stoppers until it is over 40 years old. Once the cork is extracted, the tree can be harvested every nine years.

Extraction takes place in the summer. A horizontal cut (the necklace) is made around the circumference of the tree with a very sharp axe. This is followed by a series of verticle cuts (openings or rulers). The cork bark is then gently but firmly pulled away from the tree, stacked in layers (called planks) and left to dry out before taken away to be processed.

Cork is the most environmentally friendly wine stopper. As well as being eco-friendly it is also one of the most recyclable harvests on the planet. Cork trees protect the local environment from desertification and are home to various endangered species.

About 60% of the cork harvest is used in making bottle stoppers. Other uses include shuttlecocks, baseballs and cricket balls, musical instruments, the heat shields and fairings of spacecraft, shoes and hats, and thermal insulation where it is non-allergenic and if set on fire non-toxic.

But cork has been getting some bad press in recent years when it was discovered that 1% to 5% of corks can carry a chemical compound called Trichloroanisole (TCA) which produces an odorous cork taint. Because of this, many wineries have gone over to synthetic Cellukork closures or Stelvin screw caps. While Cellukork can be very difficult to extract, the Stelvin screw cap has much going for it. Its main disadvantage is simply public perception – although more expensive to produce than cork, they are still identified with the most basic wines. They also reduce the oxygen transfer rate to almost zero which can lead to reductive qualities in the wine.

In recent years major cork producers have developed methods to remove TCA from natural corks, and as natural corks allow minute amounts of oxygen to interact with the wine for proper aging, perhaps there is still good reason to retain this noble, traditional and environmentally friendly bottle stopper.

Bill Stobbs, ABC Fine Wine & Spirits Wine Supervisor

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