Cork has been around since ancient Rome

History and production of natural cork stoppers

The Romans used to seal their wines with traditional corks. Since then, our ideas about good wine have been associated with natural cork, its pure aroma and the desirable sound when opening the bottle. For most of us, cork is also a visible sign of quality, which is why more than 90 percent of bottles are still closed with cork.

A good cork stopper is today a product of nature as much as science and technology. That natural part is the Quercus suber – cork oak tree itself. A major step forward in its use was made around 1680 by the French Benedictine Din Pierre Pérignon, who worked in the Champagne region, who introduced the process of producing champagne wine. He discovered that the original wooden stoppers, coated with cannabis and soaked in vinegar, often popped out of containers with sparkling wine. He replaced the pins with cork ones and lo and behold – this material proved itself perfectly when filling wines into bottles.

Cork is actually the bark of the cork oak, a beech-like tree characteristic of the western Mediterranean region, although its homeland lies further east. Due to favorable climatic conditions, the oak has spread in North Africa (Morocco, Algeria, Tunisia) and in southern France (especially Corsica), in Italy, in Spain, but especially in Portugal.

The Greek philosopher Theophrastus (4th-3rd century BC) discovered that when the cork was removed from the cork oak, the oak would regrow quickly and in even better quality. This has been used for centuries.

Portugal has gradually become the world's largest producer and processor of cork. Trees grown on plantations, most abundant at an altitude of 200-300 m (in the Tagus and Sado river basins), are "debarked" after reaching a certain age and trunk circumference. Because oak is a hardy tree, the scars usually heal within three weeks after the bark is removed and the tree's life begins to take a normal course again. A number of legal standards protect the oak from remaining strong, from premature aging and from developing into high-quality "harvests". These prohibit the debarking of small trees that are less than 60 cm in circumference measured at the cork at chest height, and from extracting cork from the so-called second or third cut, unless it has been forming for at least nine years.

The three-letter problem

The first peeling is possible only on trees that have reached the age of at least 25 years, and is repeated after 9-15 years. Such “stripping” can be endured by an oak for 150-200 years. The bark plates are cut and, with the help of sun, wind and rain, they are “cleaned” for the first time in the open air – they are freed from sap, tannins and water. The process can take up to a year and, according to some experts, it is at this stage that contamination with organisms can occur, which subsequently cause an undesirable smell. Other experts claim that the origin of TCA should be sought in chemicals previously used to treat oak stands. Another opinion is based on the belief that TCA is formed by the reaction of bacteria living in wine with substances used in the production of corks. In short, the origin of TCA is still not entirely clear.

The main reason is the three letters already mentioned: TCA, chemically 2,4,6 trichloroanisole. The substance, contained (not only) in natural cork, causes the so-called cork aftertaste. According to the earliest estimates, an average of five percent of bottles are infected with the aftertaste, which is compared to the smell of damp newspaper. When looking for the best stopper, the winemaker must first be clear about what he wants to use it for. It is unnecessary for table wine, intended for quick consumption, to be corked with the highest quality and also the most expensive stoppers made from a single piece of cork. However, it is absurd to save money by corking a very high-quality wine intended for archiving with short granulate stoppers. It also depends on the type of bottle that will be used for the corking. We choose a different stopper for a thin neck of a third and another for wider bottles with a capacity of one and a half liters.

Specific stoppers are designed for closing bottles of sparkling wine. They look like thick cork blocks that deform into familiar shapes in the neck of the bottle. They must be sufficiently impermeable to prevent carbon dioxide from escaping from the bottle, which would lead to the deterioration of the sparkling wine. They are made of one piece, but also glued, when two cork surfaces are glued to the lower edge, with their structure going against each other.

Cork is still number one

Regardless of the significant differences in the quality of corks, it can be stated that the uniqueness of this material also lies in its high flexibility. The cork adheres to the edges of the bottle and adapts to even minor irregularities in the neck of the bottle. Microquantities of air then reach the contents of the bottle through the stopper. High-quality, undamaged cork will prove its service to wine for up to 25 years.

When retailers or restaurant staff store wine that is sealed with corks, they should follow a few basic rules. Cork loses its elasticity if it is not in constant contact with the wine inside the bottle - therefore, wine bottles should not be left standing to prevent the cork from drying out. In a restaurant, a guest may have wine taken away whose aroma or taste is affected by a poor-quality cork. Even with good intentions, the supplier usually cannot tell if the cork is defective. Even owners of shops with a lower turnover of wine should make sure that the bottles are displayed horizontally.

Not just tradition

The cork stopper – as has been said – has been with us for centuries. It is therefore difficult to imagine, especially for wine lovers, replacing the traditional, natural cork with a new, artificial material. After all, even the soundscape accompanying the removal of the cork from the neck of the bottle seems to be an integral part of the culture of wine drinking.

Nevertheless, we are increasingly seeing attempts to replace natural cork with something new. Starting with screw caps, ending with plastic or glass stoppers. The most promising ones so far are screw caps, used mainly by Australian and New Zealand companies. The screw cap was patented on August 10, 1889 by Dan Rylands from Barnsley, but it took many years before it was first successfully used on a wine bottle. It was not until the late 1950s that the Stelvin screw cap was developed in the French factory La Bouchage Mechanique. Under the head, in the places where the cap came into contact with the wine, this type of cap was not covered by the usual layer of cork covered with paper, but by a tin layer covered with an inert plastic layer. In the 1960s and 1970s, French oenologists conducted several successful laboratory tests of the new closure. However, the French were unable to commit to commercial use. So the Swiss started today's successful push of screw caps around the world.