I thought only cheap wine used screw caps ?” was one of the many questions that I received at a wine class that I hosted recently. “That is no longer true,” was how my response began. Having received that question so many times; let me summarise the answer for our readers.

The first recorded use of corks as stoppers was by the Egyptians thousands of years ago. Cork has been the primary closure for wines from the early 1800s until now. One of the main reasons for this is the cellular structure of cork; it is easily compressed upon insertion into a bottle and will expand to form a tight seal. Some consider cork to be the best closure for wines with long ageing potential.

Issues with Cork

As with most things, some of the advantages can become disadvantages; unavoidable natural flaws, channels, and cracks in the bark make the cork itself highly inconsistent, allowing more oxygen into the bottle than is necessary. This sometimes results in different levels of ageing, creating what they refer to in the industry as bottle variation. This was demonstrated in a 10-year study by the Australian Wine Research Institute. The trial used thousands of bottles of a 1999 Clare Sémillon and sealed with 14 different closures. Once a year, researchers opened, analysed and sampled the wines in the lab. After the 10-year period, the wines under screw caps were the freshest and showed the best ageing characteristics over all the other enclosures including cork.

Cork taint has been the main reason that many wine producers began looking for alternative closures. The chief cause of cork taint is the presence of a chemical compound called 2,4,6-trichloroanisole (TCA), and/or 2,4,6-tribromoanisole (TBA), in the wine. Corked wine containing TCA has a characteristic odour, variously described as resembling a mouldy newspaper, wet dog, damp cloth, or damp basement. In almost all cases of corked wine the wine’s native aromas are reduced significantly, and a very tainted wine is quite unpalatable, although harmless. Studies vary on the number of corked wines in the industry, but between 4% to 7% have been cited by various experts; no wonder the very large producers in New Zealand and Australia are all now using alternative closures on most of their wines – mainly screw caps.

Main Alternatives to Cork

Synthetic corks and screw caps are the main alternatives. Synthetics are made from plastic compounds and are designed to look and sound like real corks. One of the main issues with synthetic corks is that they allow too much oxygen into the bottles. The other issue is that they are sometimes very difficult to remove from and to reseal the wine bottle.

Screw caps closures or “Stelvin caps” are closures made from aluminium material that threads onto the bottleneck. Screw caps form a tighter seal and can keep out oxygen for a longer time than cork. These benefits aid in maintaining the wine’s overall quality and ageing potential.

Should it matter to you?

The more informed wine-buying public understand the progress and necessary development that every aspect of wine production most go through, including the final process of closing the bottle; however, some are still deeply connected to the history and the sentiments associated with the cork. Wine producers are making closure options available, depending on the market where their products will be sold. It seems that some people miss the role of the cork associated with the ceremony around opening a bottle of wine. We should remember, however, that the winemaker has made every effort to place some fantastic wine into the bottle that he wants us to enjoy, so we should not be too concerned about the closure that keeps us from that enjoyment.

In summary, screw caps are no longer the sign of a cheap wine.

Chris Reckord – Entrepreneur & Wine Enthusiast. Send your questions and comments to creckord@gmail.com. Follow us on twitter: @DeVineWines @Reckord