The importance of cork stoppers in preserving wine

At Grandes Vinos we know that when it comes to crafting and preserving wine, there is a reason behind every little detail. From the dark color of the bottles to the cork stoppers, everything has a purpose, doing its part to ensure the wine is delicious when the bottle is finally cracked open to drink.

Every step of the process that begins with the grape harvest and ends up in a glass of wine is part of a delicate balance that brings exogenous and endogenous agents together to culminate in one of the world’s most ancient and universally popular traditions.

The cork, that apparently insignificant detail, not only serves to keep the wine from leaking out of the bottles, but also plays a much more important role in wine aging and preservation. The following are some insights that will help you understand the role that this piece of the bark from the cork oak plays.

Cork stoppers are made from cork oak (Quercus Suber), which only grows in the Mediterranean basin. Eighty percent of the world’s cork production is located in Portugal and Spain.

If you’ve ever wondered about what it does, keep reading to find out where cork comes from and the role it plays in the process of creating and preserving wine, as well as its possible replacements.

What is the purpose of the cork in wine bottles?

The cork plays a vital role in keeping wine in perfect condition. It is not only a physical barrier to external agents, but also prevents oxygen from entering the bottle, which could damage the wine.

Champagne bottles were first sealed with cork in the 17th century, and this tradition later gave way to bottles of Reserva and Gran Reserva wine. Today, cork is used in practically all bottles, though some artificial options are now available, as we will see below.

Advantages of cork stoppers

The reason why cork has been the leading choice for bottle closures for over three centuries is because of several outstanding characteristics that make it adaptable to many conditions.


Cork has an elastic memory and can expand and contract with changes in pressure and temperature without becoming deformed or less insulating. Thanks to this flexibility, it adapts to any bottle neck, guaranteeing a strong seal.


The cork promotes the micro-oxygenation of the wine, making the progressive evolution of the bouquet possible, helping the wine to mature and keep fresh. This micro-oxygenation comes from the cork and the oxygen contained in its millions of cells. It does not allow oxygen to enter, but rather it is continuously and slowly releases it from inside the cork, creating a marvelous interaction with the wine.

Beyond the time it remains in the barrel, the wine always finishes aging in the bottle. Under the right conditions of conservation, wines can last for many years, developing flavors and aromas specific to their evolution. The cork’s properties help to build up more complex compounds in the wine, creating phenolic bonds similar to those that happened before in the barrels. One of these recently discovered links is called Corklinks.


Impermeable, cork protects the wine from external agents, both O2 and any other compound, so that the wine can rest for years at no risk of spoiling.


Cork is 100% renewable and sustainable. It helps to increase biodiversity where it grows, helps curb desertification and is socially cohesive, helping to strengthen communities in rural areas.

An interesting fact is that natural cork has a negative carbon footprint, and the carbon balance can even reach -309 g of CO₂.

How can you tell if a cork is in good condition?

To know if a cork is in good condition and, consequently, if the wine it preserves is in good condition, you have to look at the color and texture of the cork. Has it leaked? Can you see any signs of incorrect bottling or rising of the wine?

Corks age as time goes by, although this does not necessarily imply a problem. Here are some issues and how to detect them. Take note.


As mentioned, the cork properties are different if it is too dry before bottling, so it may not adapt well to the neck of the bottle and may not form a perfect seal, which could lead to excessive oxidation.


If the cork does not smell like wine when the bottle is opened, but has other unpleasant odors, the wine has most likely gone bad.

Mold and TCA

There can be musty odors or TCA, a major problem in the industry in the past, which required a huge investment in R&D to solve. This is an odor caused by filamentous fungi that, by digesting a series of chlorinated particles, produce this compound that can spoil a wine. We already know that, in conditions of excessive humidity, cork can develop mold in the section opposite the one in contact with the wine.

Alternatives for sealing/closing wine bottles

Today, alternatives to natural cork are being sought in emerging markets, particularly Australia and New Zealand. Here are some of the most common ones.

Screw caps

They made their appearance at the end of the 1950s in France and are usually associated with fast-turnover wines.

Some of our Beso de Vino, which are very popular in the U.S. market, use this type of closure to meet this growing demand.

Synthetic cork stoppers

Apart from being cheaper, this type of closure is usually used for young and fresh wines, since, based on winemaking tradition, higher quality wines continue to use traditional cork.


Premium item, hermetic seal, generally for rosés and liqueurs, with an elegance that appeals to consumers. 100% renewable and sustainable.

Now that you know how important cork is in wine, you can evaluate all its pros and cons when buying. As you can see, cork stoppers go beyond a simple sealing system and are a decisive element in a wine’s taste and quality.

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