Pop or Twist? The Great Cork vs. Cap Debate

By Wanda Haynes

A wine is sealed until someone opens it, and how it was sealed can be interesting. Wine corks are an important component of a wine bottle. They have been around for thousands of years and serve as a protective barrier to wine.

Types of Corks

Wine corks are typically made from either synthetic or organic materials, namely cork oak tree and polyethylene. 

Natural corks are the most common and popular type of cork used in wine bottles because of their superior sealing ability. They are obtained from the bark of cork oak trees.

Synthetic corks have been used for many years to replace the natural cork. The synthetic resin corks are a lighter alternative to natural cork. One of the benefits of synthetic corks is that it minimizes the risk of cork taint. Cork taint is an off-flavor in wine and caused by the chemical compound 2,4,6-Trichloroanisole, which is found naturally in cork oak trees.

Champagne corks are designed to be more elastic and flatter at the bottom part of the cork. When carbon dioxide combines with a high amount of pressure, they expand and form into a mushroom-shaped cork. The attractive metal that encloses the cork in sparkling wines is called a “cage.”

Agglomerated cork closures are made from a mass of granular or powdered corks. These closures are formed by mixing cork granulates and an adhesive to form a mixture, then forming blocks of the mixture. This style of cork is tightly held together so that no oxygen can get in and spoil the wine.

How Cork is Harvested

Watch how cork trees are harvested.

The cork tree should only be harvested by qualified people, called extractors, who guarantee that the procedure does not harm or damage the tree. Harvesting is done during the tree’s active growth season, from mid-May to August. Cork may be harvested from the tree without harming it under these conditions. I recently saw a documentary where the cork trees are harvested, and it was fascinating to watch. It’s terrific to know that the trees aren’t destroyed during the process.

Looking to craft or practice sustainability with left over wine bottle components? Wine corks can be used for making wreaths, jewelry, wall art, and filling large glass containers for decoration.

Wine Bottle Caps

The twist-off wine cap, also known as the Stelvin, was developed in the late 1960s by the French company Le Bouchage Mécanique. It was introduced to combat the quality-related struggles of the traditional cork at the time. The idea was to create a tighter seal on the bottle without overexposing the wine to oxygen and impacting the flavor. Screw cap wines were not popular when the idea first originated. Many wine enthusiasts wanted to stick to the traditional cork to preserve the authenticity of winemaking.

New Zealand is leading the charge, with nearly 90% of its wines sealed with screw caps instead of traditional cork. Australia follows closely at around 80%, with South Africa at roughly 65%. The United States follows, with only about 30% of wines using screw caps.

Screw caps don’t allow oxygen into the bottle, preventing the wine from slowly aging. This makes it a good option for wines that are meant to be enjoyed young. It’s also easier to open than a bottle of wine with a cork. 

There’s More to Consider

The controversy is that high-end wines have a cork and allow the ageing process to take place more efficiently. Personally, I prefer a cork in a red wine. I also prefer a higher-priced red wine to have a cork as it shows classic bottling techniques. I’m fond of half bottles with a twist-off cap if you are consuming these wines within a month. 

Screw caps are made from aluminum, which is often produced from a mined ore called bauxite. Processing aluminum can be messy, negatively impacting the air and water and producing nearly 70 million tons of waste annually. Aluminum can be recycled, but the majority of screw caps end up in the landfill. Most screw cap liners are made from Polyvinylidene chloride, a plastic that’s unsustainable and toxic when burned. 

On a positive note: I have seen jewelry produced from using metal wine bottle caps. The artists cut the metal and don’t use heat, this way the art form isn’t toxic.

Wanda Haynes is a Certified Sommelier and wine educator living her best life. She loves parties, fine dining, gourmet chocolate, and a great glass of wine.