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The choice of cork is essential for the longevity of the wine, and although other materials are increasingly present, cork still dominates in the choice of producers. First of all, because the cells of the cork form a sort of suction cup which allows good adhesion to the neck. Then, its degradation in contact with wine and humidity is slow, it can in theory protect a wine for several decades . But it is estimated, for safety reasons, that a cork should be changed approximately every 30 years. Its reliability is, however, not completely guaranteed, in its manufacture and transport. And it happens, during tasting, that certain wines are “corked”, that is to say that we smell a cork taste.

Where do corks come from?

Cork comes from cork oaks , which grow particularly in the west of the Mediterranean basin and in Portugal. A lifting , that is to say a stripping of the tree, is carried out every twelve years, but only the fourth, fifth and sixth liftings provide high quality cork. This represents only three lifts out of the dozen expected over the lifespan of the tree.
Once torn from the tree, the cork boards are stacked and left to dry in the open air . Before being used, they must endure sun, rain and cold for two winters and one summer. During this drying, the beds lose their sap and their tissues tighten. Once the drying phase is completed, the boards are boiled in water at 100°C for 30 to 60 minutes, the cork then acquires its maximum elasticity and swells up to 20%. We then carry out an initial sorting according to two criteria: the quality and thickness of the boards, then they are left to rest for two or even three weeks in order to reach a degree of humidity allowing them to be cut.
The boards are then cut into strips whose width corresponds to the length of the future corks; these strips are then die-cut, work carried out by hand to avoid defects as much as possible. The yield is ultimately quite low, since it is of the order of 20 kg of corks per 100 kg of raw cork .
The plugs are then ground with emery in order to obtain a regular and smooth surface. They are then washed, then passed through a coloring bath to improve their presentation. A second sorting is then carried out, it can be automated by machines capable of counting the number of lenticels (small holes visible on the surface) but it is nevertheless often done by hand to be sure not to miss any defect: stain or crack .

What about the other caps?

Some producers are moving towards other types of caps, such as plastic, aluminum or even glass.
As for plastic stoppers , which imitate the shape of cork stoppers, their benefit has been verified on quickly consumed wines. Beyond three years, they tend to let air pass through, and thus oxidize the wine.
Screw caps are having difficulty establishing themselves among consumers in traditional countries, such as France, although they are already well present in countries such as New Zealand, Australia, South Africa. or Switzerland. It eliminates the danger of aromatic pollution by molecules which can be lodged in the cork, but also the risk of premature oxidation.
The glass stopper , for its part, is a more recent invention coming from the Czech Republic. This cap is relatively expensive but has the advantages of screw caps with an additional aesthetic appearance, and the sealing is done by a neoprene ring.

And the champagne corks?

Champagne corks are wider , generally 31mm while the generic diameter is 24mm, and are more compressed to be able to resist the pressure of the gas. These are the only corks that must be marked with the word "champagne" and the vintage if it is a vintage. They are inserted halfway into the bottle and only the depressed part is compressed, hence their mushroom shape.

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