Corks have been the traditional closure for bottled wine for hundreds of years and serve to protect the wine from exposure to air and hence oxidation. Today there are a number of alternative closures: screw cap (“Stelvin”), synthetic corks of various composition and most recently glass corks (“Vino-Seal”). I have had a number of customers come into the store and flatly refuse to buy wines sealed with a twist-off cap. This stems from the stigma that only “cheap” wines come in screw cap bottles. I like to point out that PlumpJack bottled half of their 1997 Reserve Cabernet ($135/bottle) with them and more high-end wineries are using alternative closures for wines that are not considered ‘plonk’. Most wines from New Zealand and many wines from Australia and Germany now come with screw-cap bottles.

What’s the real issue here? TCA (trichloroanisole) or ‘cork taint’ is the culprit responsible for spoiling somewhere between 2-10% of all wine sealed with a natural cork. Most people describe a corked bottle as smelling like wet newspaper or a dank basement. Often times though with a low level of TCA the wine is just ‘off’ and the fruit flavors are muted giving one the impression that the wine is not very good. I’m afraid all too often consumers open a bottle of wine and with no prior experience with the product determine that they don’t like it not realizing that it was a bad bottle, not a bad wine. Individual sensitivity to TCA varies widely too. Some tasters can detect as little as 2-4 parts per trillion while others cannot detect it at 50 ppt.

Where does TCA come from? It is the result of mold acting on chlorinated compounds used in insecticides, cleaning agents, etc., so the source of the TCA can be the forest where the cork came from or the winery. Somewhere in the process – from stripping the bark off a cork oak tree in Portugal to storage in the winery prior to bottling – cork can become tainted. Alcohol in the wine begins extracting the TCA as soon as it comes in contact with the contaminated cork and after a brief time the wine is compromised. It should be noted that wine can acquire TCA before it gets to the bottle too. Hoses, barrels and virtually anything that is a contact surface for wine can become contaminated and transmit TCA to the finished product.

Of course there is the aesthetic side of things to consider. Somehow going to a nice restaurant and ordering an expensive bottle of wine only to have the server twist off the top and place an aluminum cap down for you to ponder doesn’t make sense. There’s a certain elegance to the ritual of being shown the bottle and the subsequent extraction of the cork.

The ageing of wine under cork versus a screw cap is still up for debate and analysis. Historically many wines have needed years of cellaring to soften harsh tannins and allow the wine to mellow before it is considered drinkable. Will these wines behave the same with the use of an alternative closure? Many wineries are conducting these tests and time will tell.

But for the vast majority of wine the use of a screw cap is ideal. They are convenient, they can prevent most of the spoilage due to TCA and the wines they seal are meant for early consumption so we don’t need to concern ourselves with the ageability issue. I look at twist caps as a boon to the consumer.