Cork closures for wine – what’s out there and how do they differ?


Everyone knows that one of life’s great pleasures is being able to savour a glass of wine, whether in company or on one’s own. What most people probably don’t know is that one of the factors that allows us to enjoy those aromas and flavours is the cork closures.

One of its main functions is to preserve wine, contributing to the development of its character, its true identity, and enhancing its value. It doesn’t just preserve wine from external agents, it also enables the final stage of its ageing, as in the case of our Enterizo Gran Reserva, named best “reserva” red wine at the Ferevin Wine Competition.

Despite being the stopper at the last stage of the winemaking process, a cork begins its work as soon as it goes into the neck of the bottle and makes contact with the wine. It has a crucial role, as it directly influences the final quality of the wine. Today at Grupo Coviñas we want to talk to you about the importance of the cork closure.

Why do wine bottles have cork closures?

Wine needs to breathe, but equally too much oxygen can spoil wine. That’s where the cork stopper comes into its own, but let’s start at the beginning. Cork is biodegradable, renewable and recyclable. It comes from the bark of the cork oak, and the tree doesn’t need to be chopped down to get the cork. It was the elasticity of the material which caught the eye of Dom Pierre Pérignon in the mid-17th century. He was a monk from the Champagne region in France who saw how cork was sufficiently flexible to resist the pressure resulting from the secondary fermentation that produces sparkling champagne.

cork closures
Sheets of cork removed from the cork oak 

It’s this capacity to contract and expand with changes in pressure and temperature which allows it to protect what’s inside the bottle whatever the outside weather conditions. It prevents the oxidation of the wine and preserves the properties of wine over the passage of time, guaranteeing its correct development in bottle. 

Another of the notable characteristics of cork is that it is porous, which allows the micro-oxygenation of wine. For wine to age it needs oxygen. The cork closure allows the  passage of oxygen in imperceptible quantities while keeping the bottle closed and isolated from the outside thanks to another of its qualities: its impermeability

It’s important to know that cork needs to be kept hydrated, which explains why bottles need to be stored on their sides, so that the wine is permanently in contact with the cork.

Types of cork closure

cork closures
  1. Natural cork closures 

These are made from a single piece of high-quality cork with low porosity. There are different classifications based on quality and price, with FLOR being the highest category. They offer minimal permeability over the first year and from then on act as an almost hermetic seal, which guarantees an optimal closure. They are generally used for wines that require long ageing in bottle.

  1. The twin top closure

This combines an agglomerate core with disks of natural cork at one or both ends. This offers a mechanically stable closure that is of better quality than an agglomerate cork. They tend to be used for wines meant to be drunk within two or three years.

  1. Agglomerate cork closures

These are made from bits of cork left behind during the production of natural corks. They are ideal for very young wines that will not spend more than twelve months in bottle

  1. Colmate natural cork closures 

Colmate cork is highly porous natural cork that needs to be filled by a gum made with resin and cork powder. They are made from low-quality cork. They are used in wines with a short shelf-life.

  1. Multi-piece cork closures

This type of closure is generally used for larger bottles and are the result of the joining together of two or more pieces of cork and are usually used for wines intended for relatively prompt consumption.

cork closures
  1. Closures for cava and sparkling wines

These are characterized by having a larger diameter than normal corks so that they can withstand the high pressure in bottles of sparkling wine. They are made from an agglomerate core to one end of which are applied three disks of carefully selected natural cork

cork closures
  1. T-Cork closures

These are natural or colmate corks with tops made from a range of other materials (glass, metal, plastic or wood). They allow the stopper to be reused as required. They are found in Porto, Sherry or sweet Muscat wines.

cork closures
  1. ProCork closures

Cork-producing companies have research departments looking into the development of treatments to guarantee the performance of natural cork, avoiding the risk of TCA, caused by the chemical compound 2,4,6-trichloroanisole also known as “cork taint”, which gives rise to unpleasant flavours and aromas reminiscent of wet cardboard.ProCork is the result of the application of technology to natural cork; an invisible crystalline coating acts as a selective barrier that filters out the large contaminating molecules (such as TCA) but allows smaller ones (such as oxygen) to pass through it in a controlled manner.

At Grupo Coviñas we’re sure that from now on  you’ll look at corks in a new light. So, the next time you open one of our Utiel Requena wines remember the important contribution made by its cork. And, above all, enjoy that glass of wine! 

Have you enjoyed these snippets of information about cork closures? If you have, why not subscribe to our newsletter to keep up to date with inside info on the fascinating world of wine.

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