What’s with the screw cap? And what kind of wine are you giving me? is what  I thought the first time a friend unscrewed a bottle of wine. My assumption was wrong. And probably a little snobby. You have to understand that for years, a screw cap meant the wine you were getting usually came in a six-pack and somewhere on the label ‘apple’ was prominently featured. It was the kind of wine you could open and chug easily and throw up even easier.
Over time, the screw cap has gained and, for some, surpassed the cork in prominence and respectability. Increasing research into its’ benefits are emerging to support the screw caps’ validity as a high quality closure in high quality wines.

All Corked Up
For generations of winemakers, cork had been the go-to material for wine closure. If you see wine making as an expression of tradition among other things, cork would naturally be the logical choice, even with arrival of synthetic and screw caps.
Much care goes into producing a good quality cork. According to Wineanorak.com, the bark from cork Oak trees in Spain and Portugal is harvested every nine years when the trees have reached maturity, with no harm to the tree. The harvested bark is boiled to soften and cleanse it. To evade cross-contamination, the used water is cleaned, filtered and replenished regularly to withdraw any volatile elements. The cork planks are then graded, cut and either hand or machine punched. Great care has to be taken during the inspection phase because damaged or faulty corks can’t be used. Once the corks are punched, the surrounding cork material can be granulated and processed to make less expensive agglomerate corks. These corks are frequently used for champagne or sparkling wine.
Once at the winery, a ‘corker’ is used to compress and insert the cork into the neck of the bottle. Corks can be made in different sizes; the smallest (7) being used for wine that is not intended to be stored long. The larger (10) is thicker and longer, allowing less air into the bottle over time and is used for wine requiring long-term cellaring.

Just Screw It
A recent two and a half year study by the Hogue Cellars, found that wine sealed with screw caps tended to be remain fresher for longer periods of time than wine sealed with synthetic or natural cork. They tested all three types with their Chardonnay and Merlot and found that because of cork’s natural imperfections, they crumble, break, leak and while cork allows wine to ‘breathe’ it was inconsistent. Some corks would allow too much air; others, not enough.
As well, approximately 15% are contaminated by 2,4,6-Trichloranisole (TCA) a cleaning agent used to sanitize cork before bottling.  TCA is what can give the wine a musty and moldy taste. That said, sometimes, part of the ‘finish’ of a wine can be due to cork and may be part of the essence the winemaker is wanting to include.
Synthetic corks, derived from plastic, were found to cause wine to age too rapidly, decreasing shelf life by the inability to halt oxidation.
Stelvin screw caps, were shown to have a capability to preserve the quality of wine more consistently, oxidizing at a lower rate. This allowed for better long term aging and increased the maintenance of flavor and quality.
Of course, another benefit to the screw cap is that you can easily reseal your wine for storage (but why would there be any left). I can’t tell you the number of times I’ve re-corked and stored my wine, only to find a massive leak in my fridge the next day. Taking a straw to it just didn’t seem right somehow. Ick.

Pros and cons for both cork versus screw caps exist yet many are quite vehement about which side they fall on. I admit, I’m still a bit on the fence. While I’ve become more aware and accepting of the differences in wine closures, there’s nothing quite like that ‘pop’ when you open a beautiful bottle; it’s part of the experience of wine. A twist off just doesn’t have the same zing. But I’ve been put in my place and have found that what ends up in the glass can be sublime no matter how it’s sealed.

Cheers!

If you’re interested in learning about the environmental debate about corks vs. caps, click on the link for a great article by Lynn Siegel.