The Story of a Cork

Monday, July 23rd, 2007 at 12:00 am

corksCorks have been used to seal wine bottles since the 17th century. Wine bottles are being sealed to protect the wine itself from oxidizing. Corks’ elastic and highly impermeable properties were found to be a perfect sealant that prevents oxygen from entering the wine bottle. Good quality corks are made from the bark of the cork oak tree (Quercus Suber). At present Portugal and Spain are the top producers of corks with Portugal providing for the 50% of the world’s cork supply.

Cork production has always been considered an environment friendly industry and tradition. When you stripped a cork oak tree of its bark, the tree itself is not harmed. In time the bark grows back and the same tree can be harvested again after nine to twelve years. Cork oak trees can live for more than 200 years. A cork oak tree can be suitable for "harvesting" at its 25th year. But cork stoppers for wines are only made from trees that are 40 years old or over.

Kinds of cork

There are different kinds of cork for different kinds of wine bottles. But a standard cork is about 6mm wider than the internal diameter of the neck of the wine bottle. The 6mm difference makes sure that the bottle is sealed tight. Meanwhile, there’s the so called agglomerate cork which are made from tiny pieces of chopped cork that have been glued together. It’s like recycling pieces of oak bark into something that usable.

Champagne corks on the other hand have a slightly different shape that conventional wine bottle corks. Champagne corks have a slightly larger head and looks pretty much like a mushroom which allows a drinker to get a good grip of the cork when opening the bottle. This cork is usually made by sandwiching three pieces of cork together. 

Quality of cork

Although, top quality corks are still in demand they can be, at times, really expensive because of the inconsistencies in the supply since cork oak trees can only be harvested in specific number of years. Today, 70 percent of wine bottles still use natural corks as bottle sealants. However, the use of cheaper plastic, aluminum screw caps or glass stopper alternatives are steadily on the rise.

Aside from being cheaper, such synthetic bottle stoppers are being preferred since they are not susceptible to cork molds unlike natural corks which can taint, spoil and/or affect the taste of the wine. Fungal contaminations from cork molds can develop a musty aroma and taste. For agglomerate corks, some wine experts detect the presence of a glue-like aroma or taste.

The low quality of corks have forced winemakers to resort to synthetic corks or screw caps for sealing their wine bottles. Synthetic corks can be a great choice to maintain the loyalty of cork lovers and traditionalists since they can easily be made to imitate the appearances of natural corks. The main advantage of screw caps, on the other hand, is it makes it easier to re-close opened wine bottles.