Wine is usually regarded as a perishable that can be stored for years. But once the wine bottle is opened, the contents are exposed to external factors, perhaps most importantly, oxygen. This leads to oxidization, and the flavours, the taste, and sometimes even the colour begin to gradually change. In many cases, wines oxidize prematurely due to improper storage conditions and failures of the wine bottle closure system.
There is a wide variety of bottle closing systems, made of different materials:
- Crown shaped bottle caps – like beer or certain juices
- Layered cork – which comes from several joined layers
- Natural cork
Although they all have pros and cons, and the levels of oxygen permeability vary with each type, they provide the same solution: they properly close the wine bottle.
The most popular wine bottle closure systems are the traditional cork bottle cap and the screw cap (Stelvin). Over time, different methods were developed to solve the problems associated with cork, most particularly the use of aluminum bottle caps, which provides a safer form of sealing the bottle.
ABOUT SCREW CAPS
The Stelcap-wine bottle top was developed and registered as a trademark in 1959 by La Bouchage Mecanique (LBM), a French company, and later, in 1970, an Australian company was licensed to produce the sealing systems. This was the famous Stelcap closure. Eight years later, they shortened the name to “Stelvin,” as it is still known today. The production of these bottle caps continues unabated to this day.
Screw caps give the wine a consistent, almost completely airtight, or anoxic oxygen transfer barrier, which cylindrical closures do not have. This leads to fewer variations in the development of the wine, regardless of bottle, and the chances of them being affected by outside influences are much lower. There are now screw caps with various oxygen transmission rates (OTR), which allow controlled entry of oxygen (micro-oxygenation). These screw caps have small micro-perforations, and when used properly, can be a good alternative to cork, and are just as efficient at preventing spoilage or oxidation.
ABOUT CORK DOP
Corks have a history dating back to antiquity, and can even be found in ancient Egyptian tombs. They are a somewhat limited but effective resource because they are flexible, strong and impermeable to liquids. However, a small amount of oxygen does seep in, which leads to the evolution of the wine inside the bottle, which is otherwise conducive to wines that are meant to age. There is a risk, however, that a small percentage of closed cork bottles will contain a bacterium called TCA, which can ruin the aromas of the wine and give it an unpleasant odor. The plugs come in various sizes and styles, and in terms of material, can be made of either natural or synthetic cork.
According to aveine.paris (2020), 30% of US wine bottles are closed with screw caps, and in New Zealand, that percentage is closer to 90%. This is due in large part to the fact that many people consider screw caps to be a cheap alternative to cork, and think it prevents the wine from aging properly.
Perhaps the most important concern with the use of screw caps is based on the aging of the wine. According to a study by Hogue Cellars, a winery in Washington State, screw caps better retain the fruity aromas of both red and white wines. Synthetic corks have the same problems with oxidization and odour as their natural counterparts.
So we can conclude that both corks and screw caps have their pros and cons, and that both can be a good option, depending on the wine we wish to seal.