The last time you opened a bottle of corked wine, you may have noticed that the cork felt either “real” or like “plastic”. And now you are wondering what are the differences between the “real” natural cork and the “plastic” synthetic cork.
One of the big differences between the two cork types is the amount of oxygen that they let through. When oxygen comes into contact with wine, a process called oxidation occurs. And oxidation has the power to change the flavour of a wine (for better or for worse). And certain wines require a nice balance between the amount of oxygen it comes in contact with in storage. Other wines were meant to be enjoyed in a shorter period of time (ie. 1-2 years) and this is less of an issue.
The natural cork has been in use for somewhere around a quarter of a millennium. It was a huge step up in technology from the oiled rags that were used before it. Natural corks let in a very small amount of oxygen as it is porous. This makes them ideal for aging wine. They also have a nice rustic look to them as well. Natural corks are also more environmentally friendly than synthetic corks. Natural corks are harvested from a tree called Quercus suber or the cork oak. These trees can live for over 2 centuries and provide a habitat for many animals. And since the wine stopper industry uses these trees to produce their corks (as a tree can be harvested about twelve times in their lifetime), they pretty much have to provide protection for these trees.
One downside with natural corks, however is something called cork taint. This occurs when something called trichloroanisole (TCA) is leeched into the wine from the cork. One source of TCA is from the cork itself as TCA does occur naturally in some corks. And numbers do vary, but anywhere from 1% to 15% of wines are affected by this depending on who you ask. I personally haven’t encountered cork taint and I must have had over 100 bottles in my lifetime. So chances are that one of them would’ve been tainted. This is why restaurants have you try the wine first before they pour the rest. If a wine is tainted by its cork, it would smell similar to wet cardboard or a wet dog.
Synthetic corks are made from polyethylene. A great part about synthetic corks is that you don’t have to worry about smelling that wet dog the next time you stick your nose in a glass. Synthetic corks are also cheaper to produce, which is great for those profit margins if you’re in the wine stopper business.
However, it is a lot more harder to regulate oxygen intake with synthetic corks as they don’t expand and contract when the bottle does. So this could lead to an abundance or a deficiency of oxygen entering the bottle. Natural corks are much better at this and thus they are better for aging wine over longer periods of time. Synthetic corks are also harder to remove if it has been left in the wine for too long, but not impossible of course. And I have come across at least one wine opener which does not work at all with synthetic corks. There was some Teflon coating on the worm (the screwing thing), and it was too slippery to be able to remove the cork.
In the end, for regular wine that you plan to drink within the next year or so, it doesn’t really matter what type of closure it has. Both are great choices (and probably not something that would influence what wine you buy). However for long term aging of the more expensive wines, nothing currently beats the natural cork. Cheers!