Corks - Wine Stopper Breakdown

As more and more high-end wineries experiment with alternative wine stoppers, the notion that “a synthetic cork or metal cap used to seal a wine denotes a lower quality of wine,” is gradually being eschewed and leading wine makers of all levels to ask the question, “Which one is best?”

When Dom Perignon introduced the cork wine stopper in the early 1600’s it was revolutionary and became the de facto standard. But, just as the cork replaced a myriad of primitive bottle sealers, there are a variety of modern wine stoppers that may replace the traditional cork.
Along with its 400+ years of successful use as a wine stopper, the traditional cork also has the lowest impact on the environment. Spain and Portugal contain the majority Cork Oak tree farms which are solely designated for the harvesting of Cork Oak bark for wine stoppers. As cork is a great insulating material, the bark is not harvested until the tree is at least nine-years-old and fully mature; increasing the trees odds of survival during the inevitable summer forest fires. But regardless of how sustainable as the harvesting of Cork Oak bark is, it does not solve the 400+ year problem of “cork taint”. “Cork taint,” also known as “cork rot” occurs naturally when airborne fungi can travel freely into a wine bottle through the natural gaps in the cork. The fungi and alcohol combine and create trichloroanisole (TCA), the chemical fungus responsible for spoiling the wine. In 2005, Wine Spectator blind tasted 2,800 different cork-sealed wines and found that 7% of the bottles were spoiled by cork taint. Still, many will cling to the belief that a bottle sealed with anything other than a traditional cork indicates that it is a low-quality wine.
Designed to look and “pop” like a natural cork, the synthetic cork was thought to be an affordable alternative to the traditional cork and also reduce the risk of cork taint. Because the plastic compound could be created without the natural imperfections of traditional cork, it was believed that the use of these would cut down on the spoiling of wine. Unfortunately, this method of sealing a wine bottle has issues of its own. In 2007, a study done by Victor Segalen Bordeaux 2 University showed that, because a synthetic cork does not expand and contract with the bottle with temperature, like a natural cork would, imperfections in either the surface of the synthetic cork or in the lip of the bottle left small gaps in the seal. These gaps allowed for more oxygen to permeate the bottle of wine than a traditional cork or metal cap, producing more occurrences of cork taint than the other two. It’s also been noted in Wine Spectator that many connoisseurs will remark that wines sealed with synthetic caps have a slight chemical flavor. The obvious cause of this is the material used to create synthetic corks – a non-biodegradable plastic compound similar to plastic water bottles and plastic grocery bags. Nevertheless, numerous wine makers swear by synthetic corks due to their affordability and, in spite of the aforementioned studies, their reduction of cork rot due to the moldable compound used to manufacture a cork that is created to perfectly fit the opening of a wine bottle.
Australia and New Zealand have lead the charge for the use of metal caps, aka “screwcaps”, as wine stoppers since the year 2000. A New Zealand research / wine making group found that screwcaps largely reduce the amount of cork rot compared to traditional and synthetic corks. In a little over a decade, the number of wineries using metal caps in Australia and New Zealand has grown to over 90%. This can largely be attributed to the New Zealand Screwcap Wine Seal Initiative. The findings of the original research have been corroborated time and time again as more extensive testing has taken place over the last 13 years. Research has also shown that with the decrease in the permeability of the seal, comes the equally threatening risk of “reduction.” If there is absolutely no air flow between the air outside of the bottle and the air inside of the bottle, the aromas of the wine become suppressed and stagnant. This leaves the wine smelling very sulfuric, much like rotten eggs. In the 1970’s the Château Haut-Brion conducted an experiment in which 100 bottles of wine were sealed with metal caps and stored for long-term observation. After ten years of storage, the plastic used in the caps became brittle and cracked. Oxygen permeated the compromised seals and spoiled the wine. Taking all things into account, the use of a metal cap to seal a wine is a viable option if cork rot has been an issue in the past.
In conclusion, we don’t know which wine stopper is the best.
(I know – talk about a long walk for a short drink of water)
It comes down to personal preference. Many prefer the traditional cork because it’s tried & true and feel that it’s the “authentic” wine stopper, while others refuse to stray from synthetic corks or metal caps because they believe that modern innovation makes them superior to cork. Our recommendation is to explore your options and try each. Whichever one you find most successful is the best one for you… Just like the proverbial question of what is a good wine, answer, one that you like the taste of!