Portuguese cork

What do you know about Portuguese cork?

When we open a bottle of good wine, is the cork stopper the first thing we see.

A top quality cork stopper is essential for a bottle of good wine. It is not only because of the cork’s physical characteristics but also, and very importantly, for the sobriety and distinction it adds to the wine.

However, it is not only in stopper’s that we find cork. Nowadays, there are vast applications of cork: footwear, clothing, mechanical joints, thermal insulation, acoustic insulation, flooring, steering wheel covers, mobile phone covers, etc.

Please check it out, cork has a very discreet but classy presence.

Have you ever wondered where cork comes from?

Well, Portuguese cork is one of the topics that I get the most questions about during my tours, along with questions about wine.

It is an indication of, somehow, a specific knowledge about Portugal, considering that cork is one of the most important national products.

Allow me to show you some quantitative data to help me explain ​the importance that cork has in Portugal and how important Portuguese cork has in the world:

    • Portugal produces 49.6% of the cork produced worldwide (100,000 tons, 2010).
    • Portugal exports € 985.2 million out of a total of € 1578.2 million, which represents the world cork market, i.e., Portugal has a 62.4% market share in the world cork market.
    • The cork oak is the tree from which cork is extracted and is the second tree with the most significant area occupied in Portugal, 23% of the forested areas in Portugal in 2010.

As mentioned, cork is extracted from the cork oak, but how is that done?

I will then explain the necessary sequence from the land area where cork oaks are planted to the cork stoppers. However, to do that, I will need to separate in three sections: the “montado”, the cork oak, and the cork stopper.

The “Montado”

Cork oaks grow mostly in the southern area of ​​Portugal, in the region called Alentejo. The Alentejo is a region of vast plains, extreme temperatures, high thermal amplitude, and little rainfall.

However, cork oaks can be found throughout the country, but in smaller areas and more spread across the territory.

These trees grow mostly in areas that we call “montado” – sorry, no English word for that.

Knowing what the “montado” is and what his importance for Portuguese culture is halfway to better enjoy a vacation in the Alentejo region.

The “montado” is much more than a land of Portuguese cork oaks. It is an ecosystem where we can find cork oaks, holm oaks, sheep, pigs, cows, a vast diversity of birds, but also large areas of cereal plantation.

The “montado” landscape is an integral part of the Alentejo culture. It is reflected in the way of being and living of the Alentejo people, their gastronomy, the local traditional music, and everything else.

During winters, I always have periods of nostalgia about Alentejo fields. It seems like I can smell the sweet sense of golden cereal fields, and feel the warm late evening breeze of those vast plains.

Cattle are also a constant presence in the “montado”:

    • the Alentejo sheep from which wool is extracted to make Arraiolos rugs and Portalegre rugs, or from where you can get milk for the production of the spectacular Serpa cheese, which is undoubtedly among the best Portuguese cheeses;
    • the Mertolenga cows, animals of certified meat, an indigenous breed;
    • the black pig from the Alentejo also grows here, eating about 10 Kg per dar per pig of cork oak’s acorns, and the end result is a marvelous porc meat.

But, please, do not think by any means that you can call a “montado” to all set of cork oaks.

A group of cork oak’s, just like that, without the comprehensive ecosystem, we call it a “sobreiral”, planted as a more intensive crop, where these trees are closer to each other. Many of the characteristics of the cork do not exist here, such as biodiversity.

A “montado” is quite different from a “sobreiral,” and there are mainly two kinds of “montado”:

    • the one where we can find pasture for animals, and where they roam freely;
    • and the “montado” with cereal fields, and where we see the cork oaks widely spread out as sentinels. 

These two types of “montado”, although different from each other, share many essential characteristics.

When walking on the “montado”, we can notice some numbers painted on the cork oaks. 

The number corresponds to the last digit of the year in which the tree was stripped out from its cork.

From the number painted on the tree, we know that nine years later, we will have to peel out the cork again.

The cork oak

The cork oak is a tree of the oak family. Its scientific name is Quercus suber.

Like any other oak, it bears acorns. These are the acorns the aforementioned black pigs eat, and that will definitely contribute to the excellent taste of pork meat.

These medium-sized trees, about 15 m high and never more than 25 m in exceptional cases can live up to 200 years or more.

The oldest cork oak in the world is in Portugal, in a village called Águas de Moura. It is called Whistler, Sobreiro Assobiador in Portuguese, because of hundreds of birds usually there in an impressive clinking.

The Whistler was planted in 1783 and is over 14 meters high.

In 2018, this a Portuguese cork oak tree won the European distinction of “The Tree Of The Year.”

I can estimate, since 1820, this cork oak has undergone many cork stripping, perhaps about twenty. In 1991 it was an exceptional year in which 1,200 kg of cork was removed, giving place to more than 100,000 cork stoppers.

Cork stoppers are the most important product of the cork industry, but I will deal with that later.


Cork is the outer part of the cork oak trunk.

It consists of dead plant cells that are no longer physiological. Therefore, removing the cork from the tree does not damage it, it is like cutting nails for humans.

As far as I know, we can only extract the cork from cork oaks. But, if anyone knows of any other tree from where we can do that, please let me know.

The process of growing cork is a very long one.

Around here, in Portugal, people say that one hardly harvest the cork from the cork trees one planted, and I will explain why.

Allow me to share with you the various steps until we can remove a good cork from the corks oaks we planted:

    • First stripping at 25 years – Two conditions must be met so the first stripping can take place. The tree must be at least 25 years old, and at 1.3 m from the ground, the perimeter of the trunk must be 70 cm or more. This cork is called a virgin and has low commercial value.
    • Second stripping at 34 years – It will happen nine years after the first stripping. Although this cork is still not the best and is not suitable to produce cork stoppers, it is already good enough to produce granules and other products. It’s called a “secundeira”, the second one.
    • Third stripping at 43 years and onwards – It will happen every nine years. It is called “amadia” or reproduction cork. From this moment on, the cork will have the quality needed for cork stoppers or any other product derived from cork.

From here, we can move on to the production of cork stoppers.

Before we move on to the cork stopper chapter, it is necessary to describe the stripping process a little.

Stripping cork oaks is an ancestral art, is still wholly manual today, and without perspectives of finding a machine to replace this hard manual labor.

It is a tough job, done during a scorching period of the year, between mid-May to the end of August when temperatures can quickly rise up to 45º C.

It requires a lot of expertise. The workers use only an ax which, skillfully maneuvered, removes the large cork boards that will later be taken to the factory.

Once the cork boards are removed, they will be transported to the factory.

At the factory, the boards will be boiled to remove impurities and to be flattened, so they can be calibrated and transferred to the production.

Depending on the quality of each board, so it will depend on what will be done with them.

Unfortunately, I can’t describe here all the products produced with cork, so I will select cork stoppers to develop a bit more.

Anyway, I’ve selected a few interesting links you can visit if you are interested to learn more about cork products:

Shuttle’s Cork From Portugal 

Foam and Cork Insulation Protects Deep Space Rocket from Fire and Ic

How durable is cork fabric?

How cork fabric is made

Cork stoppers

Considering 2016 data, Portugal’s turnover in the cork industry was 1,466 Mio €, of which 785 Mio € correspond to the manufacture of cork stoppers, which is 53.5% of the cork market in Portugal.

Yes, uuuuaaauuu …

Did you know that initially, cork stoppers were produced from rectangular cork pieces with the final height and then manually adjusted to the desired diameter?

Only at the beginning of the 20th century, the machine was invented to do that job. The so-called Galorpa started the industrial production of stoppers.

I will not describe the full production process. However, in its production, there are two steps I find fascinating:

    • Visual selection: despite each cork stopper being electronically inspected, the human eye is required to determine the quality level of the cork stoppers.
    • Marking is also essential. With ink or fire, each cork stopper is marked with the distinctive customers’ mark as to later be a guarantee of the wine’s authenticity when opening. Now you know why the Sommelier gives you the cork stopper after opening an expensive wine bottle.

The commercial threat plastic, rubber stoppers, and metal caps represent for the cork stopper market are well known.

In less expensive wines, and in many countries, artificial stoppers are becoming used more frequently. That is not happening in Portugal yet.

Despite that, some cork alternatives are being introduced in the market to compete against artificial corks. Is the case of the Helix system of Corticeira Amorim.

 for which I wish the greatest success of all.

Environmental impact

Perhaps this part will bring many pleasant surprises.

At a time when the world is increasingly aware of environmental issues, it is good to know how each industry contributes towards reducing its ecological footprint.

The contribution of the Portuguese cork industry could not be better, absorbing more carbon from the environment than what it produces.

From a document by Corticeira Amorim, the largest cork company in Portugal, we can read:

“The worldwide scientific community now accepts that emissions of greenhouse gases are responsible for the phenomenon of global warming.

The forests are a major partner in this fight, since through photosynthesis trees absorb carbon dioxide which is converted into organic tissue. The carbon is captured and stored in the trunk, branches and roots of trees and in the forest soil.

Since the cork oak has a long life span, it promotes the storage of carbon like no other over very long periods of time.”

“According to a study conducted by PricewaterhouseCoopers and Ecobilan (in accordance with the ISO 14020 and 14044 standards) on the life cycle of cork stoppers versus alternative closures (aluminium and plastic), cork stoppers are the only environment-friendly choice. In other words, cork is the best closure for wine producers who want to minimize their carbon footprint and adopt the best environmental performance practices. ”

“The cork oak has a capability to absorb 14.7 tons of CO2 per hectare.

Extrapolating to the global area of cork oak forests, the western Mediterranean has a retaining capacity of about 30.66 million tons of CO2”

You can download this document here

To finish

To wrap up this subject I will leave you with one of the best documentaries I came across:  BBC Cork Forest in a Bottle

I hope I was able to contribute to your knowledge about Portuguese cork and to better appreciate the cork products that you may buy in Portugal.

Carpe diem

David Monteiro

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