Cork. Is a good cork important?




Selected corks of wines I drank and reviewed.

 As a stopper for bottles, cork has excellent characteristics for wine. Looking at cork under a microscope, one can observe that it is formed by a net of millions of cells. Each cell wall is formed by an organic substance named suberine, which originates from a transformation of cellulose and is known for its waterproof and elastic characteristics.

Although it has its critics,Cork has been used for such a long time to seal wine bottles that one tends to overlook its remarkable characteristics which are born from simple tree bark. In fact, cork is the external covering of the cork oak, a tree species that grows mainly in Spain, Portugal, France, Sardinia, Algeria and Morocco.  The bark is harvested  every nine years from selected cork oak trees, and no damage is really done to the environment as the tree does not have to be cut, but simply the bark is peeled of, which then grows again over a period of some months.

Thanks to cork, the wine receives very small doses of oxygen that allow it to evolve over time. This is due to two elements: 1. the natural porosity of cork, and 2. the small space that remains between the bottle's wall and the cork's lenticels. These are small imperfections on the cork which may be seen with the naked eye. They are openings through which oxygen passes from the atmosphere into the tree. In the case of a cork, wine, bottle stopper, lenticels are very important. The greater the amount of these openings, the less a cork will last, therefore cork stoppers have to be selected with due care and dilligence if premium wine is to be aged in bottles for a lenght of time. For premium wines, corks must be long, as smooth as possible and without lenticels. Corks with more lenticels may be used to keep wines that will be aged for a short period of time.

"Screw caps" were introduced in 1959 by a French company, which had introduced the Stelcap-Vin cap which had already proved successful for a range of spirits and liqueurs. These screw-caps are inert and can last for many years, in fact they have kept certain wines, red and white, in good condition for more than 30 years. However, controversy still remains over whether they are the best closure type for red wine destined for long ageing and for some styles of white wine. While some scientists argue that wine ageing is an anaerobic process most successful in the complete absence of extrinsic oxygen, others suspect that the tiny particles and amounts of oxygen that are transmitted by the less than perfect seal of corks, is important for red wine ageing. Only long term trials with red wines sealed under different closures, will eventually resolve the issue.

Good quality cork, is imprevious to air, almost impermeable by water, difficult to burn, resistant to temperature changes and vibration, does not rot, and has the ability to mold itself  to the shape and contour of a container it is put into, such as the neck of a wine bottle.

There are also agglomorated corks that are made from small particles of cork that are bound together. These are useful for wines that are bottled for immediate consumption.

Bad quality cork may produce a chemical substance called TCA,2,4,6-Trichloroanisol, a feaful chemical substance that gives a wine a bad taste of humidity and mould. This leads to the very undesirable "corky" or "corked" wine, which wine would have a musty aroma of wet newspapers, mushrooms and rot. Although drinking corked wine is not harmful to one's health, it makes a wine very unpleasant to drink, and is not recommended. If you are ever served a "corked" wine in a restaurant, do not hesitate to refuse it, politely but firmly.