The cork is an important part of the wine experience and wine itself. It does not solely act as a stopper for the wine bottle. The cork is necessary for the preservation and proper aging of the wine.
It is also satisfying to hear the pop of the cork as you open a new bottle.
What is it and Where does it Come From?
Corks are made from the bark of the Cork Oak (Quercus Suber). The Beach and Chestnut trees, grown in America, are in the same family. However, the bark of the cork tree is much thicker.
The cork is ideal for wine storage because it is malleable enough to get in the bottles and slightly porous to allow the aging of wine.
The oak is native to the Mediterranean basin which includes the North African countries of Algeria, Tunisia, and Morocco. These trees are also grown in Southern France, Italy, Spain, and Portugal.
Many of these trees are grown in cork forests that have thousands of Cork Oak in them. Fortunately, these trees can grow in an extremely dry and barren land, allowing these countries to utilize land that would otherwise be useless.
The trees can reach 60 feet high and 12 feet in diameter.
How it’s Made
Cork trees take around 25 years after planting to have viable bark. After initial harvest, the trees take about 7-10 years to grow the bark thick enough to harvest again. The bark that is ready to harvest is 2-3 inches thick. The trees stay alive even after harvest so you are able to harvest trees multiple times.
During the harvest of the cork, the bark is taken off in large pieces. Afterwards, the strips of bark are sent to a factory where the bark is further cut into more manageable strips.
The cork bark is then laid out to dry for 1-6 months. Before further processing, the cork is boiled in order to sterilize and soften it.
High-quality pieces of bark are punched manually while regular bark is punch automatically in order to extract the wine corks.
The corks then go through another heat treatment in order to kill the bacteria that may be lingering. The corks are then packaged and sent to wineries for the bottling process.
Some corks are then covered in a thin layer of wax if the manufacturer wants a waxed wine stopper.
No cork goes to waste either. Extra bits of cork and low-quality pieces are shredded and then pressed together to make new corks.
That’s it. It is actually a very simple process and cost-effective once the bark is harvested.
There are different levels of quality when it comes to corks. High-quality corks will only be porous enough to allow 1 milligram of oxygen into the bottle each year. This allows the tannins to soften and the wine to age slowly.
Keep in mind that corks from sparkling wine and homebrew are made into a different shape that allows for easy opening and will not pop under the pressure of the wine.
Fun fact: Cork trees also produce acorns.
Prior to the use of cork, cloth and leather were used to seal the wines. Later on, clay and wax were added in order to further protect the wine.
In the late 1600s corks really took off and production of these corks was made easy. Surprisingly, it wasn’t for another hundred years before easy-to-use corkscrews were made.
It was during this time that winemakers and consumers really saw the benefits of using cork. It was perfect for sealing glass bottles, it was cheap to produce, it allowed the wine to stay good longer, and it aided in the aging process.
While there are now many alternatives, it has become traditional to use corks in the winemaking and bottling process.
Positives of Natural Cork
- Helps age the wine
- Renewable resource
- Grown in some of the world’s most barren land, allowing these countries to utilize land that would otherwise be useless
Negatives of Cork
- TCA/cork taint
- Sensitivity to temperature fluctuations
- Must be imported to a majority of countries
- Screw caps- Screw caps were invented and further popularized by Australia and New Zealand. In fact, it is not often that you find a bottle from these countries that uses cork. Even the finest wines use screw caps. Screw caps ensure that your wine stays TCA free, it makes storing the wine much easier, and you can fully customize the cap to let a certain amount of oxygen in. This is great for wineries who want their wines to age a certain way.
- Artificial/synthetic corks- Synthetic wine corks are made from plastic and look more like rubber. Typically, bargain wines use these corks. Unfortunately, they are not a renewable or environmentally friendly tool. It is also hard for them to create a firm seal on the wine, allowing the wine to oxidize and age quicker than with natural cork or screw cap. However, one benefit is that they are fairly TCA-resistant and are not as sensitive to temperature fluctuations.
- Sugarcane corks- The best and most underrated cork alternative is recycled sugarcane. Sugarcane corks are made from unused sugarcane stems. Not only a renewable resource but the sugarcane is very cheap to purchase initially. It is the process of getting from the cane to the cork that is expensive. Sugarcane corks seal well, allow little oxygen to get into the wine, are TCA and bacteria-resistant, biodegradable, and not temperature sensitive. The two major downsides are the cost and lack of availability, making cork stoppers more appealing in some cases.
- Boxed wine- Boxed wine is an extremely popular choice for bargain wines, especially those coming from Australia and New Zealand. They are easy to ship and stack. These boxes are also able to fit a lot more wine in them than traditional bottles. Boxed wine is much more economical for those exporting their bottles of wine. Once open, the box of wine will stay good for months because they don’t use traditional bottle stoppers.
- Recycled cork and cork pieces- Many wine producers have started using recycled corks and corks made from stray pieces of cork. These corks are sanitized, shredded, and glued together to form new corks. This also included agglomerated corks. These corks are made from cork pieces and synthetic material.
Start paying attention to the corks in your wines. What material are they made from? Do you notice a difference in cork from affordable wine to premium wines?
Checkout DIY projects like cork boards that you can make from your leftover cork closures.