Corks Seal a Wine’s Fate: Aging Wine in Natural vs. Synthetic Closures
Most foods are best as fresh as possible. Wine differs from food in this respect as many wines that actually need some aging to taste their best. Winemakers know this, and part of their winemaking process is to control the aging process. Included in this is their decisions about how to bottle up their product.
Aging and oxygen
When aging a wine the process of how fruit acids react with the alcohol reduces sourness in the wine – this is really only important for very tart wines, the ones coming from cold climates.
The second aspect of aging is the complex oxidation process. When oxygen interacts with a wine, it produces many changes – ultimately yielding an oxidized wine that has a nutty aroma.
Many wines develop undesirable aromas under anaerobic –no oxygen– conditions; a small amount of oxygen will eliminate those trace thiol compounds responsible for the aroma of rotten eggs or burnt rubber. Oxidation products also react with the red anthocyanin molecules from the grapes to create stable pigments in red wine.
Which sealing method is best?
The way a bottle is sealed will directly affect how much oxygen passes into the wine each year. That will directly affect the aging of the wine and determine when that wine will be at its “best.”
No oxygen can pass through glass, so it is considered a hermetic material. At the same time all wine bottle closures admit at least a little bit of oxygen. The actual amount is the key to a closure’s performance. A typical cork will let in about one milligram of oxygen per year. This sounds like a tiny bit, but after two or three years, the cumulative amount can be enough to break down the sulfites that winemakers add to protect the wine from oxidation.
Natural cork stoppers appeared about 250 years ago, displacing the oiled rags and wooden plugs that had previously been used to seal bottles. With the use of cork came the possibility of aging wine. Until about 20 years ago natural corks were pretty much the only option for quality wine. The cork cylinder is cut from the outside to the inside of the bark of the cork oak tree.
2. Plastic corks
Synthetic corks are made from polyethylene, the same plastic as milk bottles and plastic pipes. After years of research and development, these corks perform nearly the same as the natural version with three exceptions: they have no taint, they let in a bit more oxygen and they are very consistent in oxygen transmission.
Their consistency is a major selling point to winemakers because the wine will have a predictable taste at various points in time. In fact, winemakers can tweak the oxidation rate of their wine by choosing from a range of synthetic corks with different rates of known oxygen transmission.
Screwcaps are actually two parts: the metal cap and the liner inside the top of the cap that seals to the lip of the bottle. The liner is the critical part that controls the amount of oxygen getting into the wine. Back when screwcaps were only used on jug wine, there were just two types of liners available. But today multiple companies are jumping in to offer their take on what rate of oxygen transmission is best, as well as to replace the tin used in one of the traditional liners. The standard liners admit either a bit more or a bit less oxygen than good natural corks. Screwcaps, being manufactured, are also very consistent.
Is there an optimum wine closure?
Performance of the manufactured closures, made with 21st century technology, is excellent. Generally they approximate our expectations, based on over two centuries of experience aging with natural cork closures.
For the regular wine you might purchase for dinner this weekend or to keep for a year or two, any of these closures are perfectly good, while the manufactured closures avoid taint. In fact, your choice is more a matter of preference for opening the bottle. Do you want the convenience of twisting off the cap, or do you want the ceremony of removing the cork?
For long aging however, the only closure with an adequately long track record is natural cork. So to be safe, that is the closure to choose. Once we have solid long-term evaluations of synthetics and screw caps, it will be possible to judge their suitability for extended aging – this would need to be more than ten years from now.
Over centuries, winemakers have consistently taken advantage of new technology to improve their product, from oak barrels to bottles to modern crushing and pressing equipment and micro-oxygenation. While manufactured closures have some key advantages, it is proving difficult to displace natural cork due to its centuries-old tradition, albeit with a few problems, and its connection to the natural environment.
How to stopper /close /preserve opened wine?
We recommend Le Verre de Vin. Le Verre de Vin is the only wine preservation system capable of effectively preserving an unlimited number of still, sparkling and fortified wines. Le Verre de Vin (“the glass of wine”) was invented in the U.K. in 1992. Its launch was the culmination of two years of research and development by a team of engineers and wine professionals.
The innovative processes and technology incorporated within each unit are so advanced that the system has won fully granted patent status in all the major wine markets around the world.
Since its launch, Le Verre de Vin has won widespread acclaim from the thousands of hoteliers, restauranteurs and operators for whom it plays a pivotal role in the service of wine by the glass.
The machine quickly and easily removes oxygen from open bottles of wine to a precisely controlled level effectively preserving the subtle structure of the best wines for up to 21 days.
In the case of sparkling wine or champagne, a buffer of carbon dioxide gas is inserted into the head space above the liquid preventing any loss of the natural sparkle in the wine.
This simple technique ensures pristine preservation for 21 days.
- It is the only commercial-grade wine preservation system that is able to re-seal an unlimited number of opened bottles of still, sparkling wine and champagne in just 3 seconds.
- It is the only preservation system that creates a precisely controlled preservation environment irrespective of how much wine remains in the bottle.
- Ensures that every bottle will remain fresh in prime drinking condition, for up to 21 days.
Contact us today for more information to see how Le Verre de Vin’s affordable preservation technology gives your establishment the opportunity of making the wine drinking experience even more exceptional! Call us on 021 788 9788 or email us at