As you may or may not have noticed, screw caps seem to be taking over. To some of you that may sound quite scary, but it’s not necessarily a bad thing. In fact, for some wine lovers it’s a GREAT thing!
If you like your wine to be more on the fruity side with bold aromatics, then screw caps are for you. That’s not to say that all wines with screw caps fit that description, but it is true for most. When a bottle is sealed with a screw cap, it essentially creates a perfect seal; one that does not allow oxygen to pass through it, as a cork does through its porous structure.
Screw caps allow winemakers to bottle the wine once they believe it has reached its true expression or desired flavors. At the point of being content with the process, winemakers can then bottle with a screw cap and be secure in knowing that the wine will be fresh for the consumer for quite some time, without the worry of cork taint (more on that in a minute).
The inability of oxygen to permeate through a screw cap, creates a freshness in the wine that can not be matched by natural or synthetic corks. That being said, there is another issue that can arise: reduction.
Reduction is the opposite of oxidation; meaning reduction is when wine is aged without oxygen. This process creates exaggerated fruit flavors and floral aromas, but can also lead to the creation of some sulphur flavors like rotten egg or burnt matches. This downside of possible sulphur flavors, however, is seen by most winemakers as less damaging to their product than cork taint.
Now, the good and the bad about cork: The beauty of cork is its ability to breathe. Cork is a porous material, which allows small amounts of oxygen to reach the wine. This process helps the wine to slowly age and to reach maturity. Wine is after all a living thing, just like the fruit that created it, and most living things do need oxygen to develop. This leads to one of the serious drawbacks of cork; it’s an imperfect material. Some corks will allow very little oxygen and others can allow so much that the wine becomes oxidized within the first two years of being in the bottle.
Naturally, we’ve all heard of the ever elusive term “corked”. This is another downside of corks. Since cork is from a living tree, cork can be imperfect or tainted. For example, the tree bark used to create corks may have had a fungal infection in some part of it which, if gone untreated, could potentially create a number of corks affected by TCA (Trichloranisole). This, along with various other compounds found in natural cork, can cause musty odors and be very off-putting.
TCA is not only found in nature. It can also invade wineries and bottling lines whether it be via oak barrels, building materials, etc.. The alternative to natural corks (in keeping the allure of using a corkscrew and “popping” the cork) is synthetic corks. These have another set of issues.
A study done by the Australian Wine Research Institute concluded that synthetic corks are responsible for absorbing a considerable amount of wine aromas and flavor. Natural corks can also absorb these aromas, but in smaller amounts. So it is true that if you want a perfect seal, the only real way to go is a screw cap.
There is another underlying issue here. We’ve been bottling wine with corks for centuries and we’ve grown accustomed, not only to the ritual of popping a cork, but to the chemical reactions that occur between wine and cork in the bottle. These reactions create an entire other layer of aromas and flavors that can not be matched by a screw cap.
The technology behind cork production has evolved quite substantially in the last few decades, which has led to more reliable and consistent corks, but they are still imperfect. An estimated 5% of all bottles with natural corks will be infected by cork taint. So if you consistently want a fresh bottle of wine without the risk factor, you should look for a screw cap, as they have been proven to preserve the true flavors intended by the winemaker at the time of bottling.
Though most high-end winemakers producing wines with real age potential are still hesitant to bottle with screw caps, they are beginning to experiment. The time of cork being the most common seal for a wine bottle is drawing to a close!