Natural Cork versus screw cap (alternative closures)… this debate has been around for a long time. Let’s look at the Who, What, When and Why about wine bottle closures and you can evaluate for yourself. 

What 

There are many varieties of wine bottle closures, and they each have their place in the beverage industry. Let’s look at a few of the major types of closures. 

Natural Cork: While natural corks have been used since the ancient Greeks, it wasn’t until the 17th century (after the advent of glass bottles) that it became a standard sealing method. The material comes from the Cork Oak (Quercus suber), primarily coming from Spain and Portugal. 

Granulated Cork: This type of cork uses granulated pieces of natural cork, forced together to form a composite cork shape (think particle board, recycled plastics, etc.). Obviously, these corks generally cost less, and are generally for wines that should be consumed sooner rather than later. 

Technical Cork: This type of cork is kind of a hybrid of granulated and natural cork. The top and bottom discs of the cork are made with natural cork, but the in-between filling is made with granulated cork (e.g., Champagne corks). 

Screw Cap or Screw Top: This is exactly what it sounds like. The most well-known brand of screw cap is called Stelvin, which is currently owned by Amcor. These metal caps have a plastic disc interior that seals tightly again the mouth of the bottle, reducing oxidation, and are a less expensive alternative to natural cork. 

Synthetic Cork: These corks are made of synthetic materials, such as plastic, rubber or other composite materials.

Capsulated Cork: This type of cork is also known as T-cork (named after its shape), and is primarily used in beverage categories of fortified wine and other spirits. It is again another type of hybrid closure. The bottle part of the cork is made using natural cork or synthetic materials, and the cap on top is made of a separate type of material (e.g., plastic, wood, glass, metal). 

Fun Fact! Other than these primary categories of closures, there are other unique products out there! Vino-Lok is a stopper made of glass (or plastic), and has an airtight seal that prevents oxygen or bacteria from entering the bottle. Zork is another unique type of closure that seals like a screwcap, but “pops” like a cork. 

Why 

Wine closures affect the way a wine tastes. Different materials result in varying levels of cost, sealing capability, protection against oxygen, etc. In recent years, winemakers and consumers now consider carbon footprint and environmental impacts. 

Natural cork does tend to be the best form of bottle sealing, as it provides the ideal amount of oxygen entry into the bottle to help wines age. Cork has the ability to maintain the tight seal and resist moisture. Unfortunately, the major factors that negatively affects the cork market is 2,4,6-trichloroanisole compound (TCA), more commonly known as cork taint. Later research reveal that TCA is also found in water, wood, soil, etc., so the wine could have been exposed to TCA before even entering the bottle, but the initial discovery had damaged the cork reputation. 

Today, the percentage of TCA presence in corks has reduced significantly (from ~10% to now less than ~4%) due to extensive research and testing. 

When 

During the 1980s, screw caps were still new, and tied to the idea of being “cheap.” Up until that time, the vast majority of bottles were being sealed with natural corks. After the 1990s issues when cork was connected to TCA, the cork reputation was damaged to the point where a wine affected by TCA was considered “corked.” Entire countries like Australia and New Zealand traded natural cork closures for screwcaps instead, and the majority of producers remain loyal to screw caps today. 

Who 

In general the latest trend towards preferring environmentally friendly, sustainable products have taken the world by storm. This trend applies to the cork market as well. In 2008, Amorim, the world’s largest cork producer, published a report showing that natural cork performed better than plastic and aluminum closures for environmental impacts. 

This year, Amorim revealed new research advancements that uses a specialized form of gas chromatography (GCMS) to detect TCA in corks. The technology allows Amorim to offer “guaranteed and insured corks.” This is unheard of, and surely is exciting news for natural cork wine bottlers everywhere. 

Some winemakers have begun to shift back to using natural cork, not only because of advancements of natural cork and environmental impact, but also to increase market share in places that continue to have the classic perception of quality wines that natural cork has. 

Fun Fact! Two countries that heavily prefer the natural cork (due to perceived quality) are China and the U.S. 

The next time you purchase a bottle of wine to drink, think about all the different factors and considerations that go into only one decision point during the winemaking process. For the wine industry professionals, it’s perhaps time to re-evaluate wine closures and the recent technology and research revelations that have come to light. 

Until next month, Cheers~!

Alice