The cork and the wine

One of the most important factors for further maturation of wines is the sealing of the bottle. 70% of winegrowers in the world seal their wine bottles with corks. It is also necessary to transport and store wine easily. Where is he from ? What are its variants and what types of wines can it seal? How to extract it from a bottle?

Cork: a material with unique properties

Cork is the bark that is stripped from the trunk of a tree called a cork oak. This one has the capacity to regenerate its bark in a natural way each time it is stripped of it, and develops mainly in the countries of the Western Mediterranean (Portugal, Spain, Italy, France, Morocco , Tunisia and Algeria).

Cork is obtained only every nine years at the earliest, and after the tree has reached a certain maturity. It has a long list of characteristics that make it a unique material.

Indeed, it is an excellent thermal and acoustic insulator; it is impermeable to liquids and gases, flexible, biodegradable, recyclable and soft to the touch. It has excellent resistance to fire and high temperatures, high resistance to friction, good elasticity and compressibility, and extreme lightness. It's rare to find so many properties simultaneously in a single material.

These particular characteristics of cork have been used for centuries to produce bottle stoppers . It is also in the field of wine that this material will be the most adopted, because its insulating properties better protect wines against temperature changes, and allow them to be better preserved. However, it is not used in one form for all types of wine.

Types of cork stoppers suitable for each type of wine

There are a wide variety of bottle stoppers used to seal and preserve the contents of the bottle. The wine industry primarily uses cork stoppers. It is arguably the largest consumer of these corks worldwide.

Not all wine corks are the same , and some are more reliable than others depending on the type of wine that needs to be sealed. Thus, each wine has specific storage and aging needs, and the type of cork affects the flavor of the wine in some way over time. This is why winemakers use different types of cork for different types of wine.

  • Still wine corks

Several categories of cork stopper are generally used for bottling still wines:

Natural cork stoppers

Natural cork stoppers are obtained directly from the bark of the cork oak. They are extracted in one whole piece through cutting techniques, and depending on the latter, can have cylinder or cone shapes with varying sizes.

Totally natural, they allow the wine to age in the best conditions. It is their excellent sealing capacity that is the basis of the best conditions for the evolution and maturation of the wine. They are also recommended for reserve wines and wines that require aging in the bottle.

The ability of natural cork stoppers to remain airtight over time very often depends on the choice of their size, but also on a good specification of their diameter. Thus, their size is usually large enough to withstand the effects of temperature changes, and their diameter often exceeds that of the bottle neck by at least 6 millimeters.

They are inserted into the neck thanks to compression, which often does not exceed 33% of their diameter so as not to destroy their cells. This is why when mined they may have retained the vast majority of their original size.

Multi-piece natural corks

These wine stoppers are made from pieces of natural cork which were not very thick at the start, and which could not give a one-piece stopper as above. Their purpose is usually to seal larger bottles that could not be closed with a one-piece cap.

They are used much more for wines that do not need to be aged for long periods. Moreover, the products used to glue the pieces are not harmful to consumption.

Clogged natural corks

They use the same natural material as the previous plugs, but lack many of the tiny holes (pores) that are often found on plugs.

Natural powder is used to fill these holes from proper processes, which gives better mechanical performance and less heterogeneous appearance to these bottle caps.

Agglomerated corks

They are produced by extrusion or by individual molding, which are processes that allow the cork granules to be glued together in order to obtain a homogeneous whole.

These granules come from the residues of the materials used to produce natural corks, and represent the main component of agglomerated corks. The latter are very economical and widely used by producers of inexpensive wines, and can only be used to cork wines whose conservation does not exceed one year.

Microgranule plugs

They are similar to agglomerated corks in terms of composition, but are produced from finer particles and have a very small size (1 millimeter on average). They are best used on bottles of complex wine that are quickly consumed.

Technical plugs

They are mixed wine corks, consisting of two natural cork discs at each end, the middle of the discs being completely agglomerated. They can be produced in several forms, just by varying the number of cork discs to put on the ends.

These bottle stoppers are ideal for storing wines that require up to three years of aging.

Synthetic corks

They are made from plastic materials and synthetic cork instead of natural cork, in order to avoid leaks (or leaky bottle) and possible contamination by TCA (Trichloroanisole, responsible for the famous cork taint) .

On the other hand, they can cause oxidation of the wine and give it a petroleum smell after a certain time, because of the materials used in their manufacture.

  • Corks for sparkling wines and champagnes

They comprise a main body of agglomerated cork with two roundels or discs of natural cork at each end, which remain in contact with the wine.

Some may have just a cork, and others may not even have any depending on the specifics of the wine. They are intended for wines that combine extreme pressure with subtle delicacy, such as champagne and sparkling wines, sparkling wines and ciders. An undisputed option for the best champagnes in the world.

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Extracting the cork: a matter of corkscrews

The purpose of corking a bottle of wine is not to condemn the liquid, but to facilitate its storage and transport in the best conditions, and to allow it to keep properly. At the end of the maturation period or simply at the time decided for the tasting, it is obviously necessary to uncork the bottle. It is with this in mind that the "corkscrews" were created.

Appearing at the beginning of the 17th century, corkscrews have evolved a lot aesthetically and technically, going from a simple spiral to ever more convenient arrangements. We find for example:

  • Corkscrews with double supports, which allow the corks to be extracted vertically and in two movements;
  • Bimetal corkscrews, very convenient for extracting weakened corks;
  • Corkscrews called "screwpull", a little more expensive, but very useful for extracting robust corks without too much effort, and therefore well indicated when it is necessary to extract a lot of corks;
  • Lever corkscrews, as popular as they are practical;
  • And even gas corkscrews, which use the action of gas to extract the cork.