Team Cork or Team Screw Cap: where do you land?
2k years ago, the Ancient Romans are credited with being the first to use cork as a sealant. They didn’t use cork exclusively and eventually its use was historically lost. Other products historically used to seal wine include cloth, leather, clay, wax, ceramic, glass and pine resin (most notably associated with Retsina wines of Greece which are still made today with pine resin and the flavors you might imagine).
Q: Which do you prefer?
Me? I like them all for different reasons!
Benefits of Cork
In general, oxygen is the enemy of wine. It causes the color to brown and the flavors/aromas to dissipate. But applied in small amounts under controlled conditions (as in through a cork slowly over time) it can enhance the wine. Now you know!
The beauty of cork is that it allows a minimal amount of O2 into the wine and thus minimal oxidation. A high quality cork will allow ~1 milligram of O2/yr into the bottle. This little bit of oxidation is just the right amount to soften and evolve the wine without degrading it and causing it to spoil too quickly.
What is Cork? Cork is produced from a spongey material taken from the bark of cork oak trees. Cork keeps growing after the bark has been harvested, but because it takes so long, the trees can only be harvest once every 9 years!
The Drawbacks of Cork
Wine corks are not perfect however, the major problem being TCA, which effects the quality and taste of 2-5% of wines. TCA (or "cork taint") turns fruit flavors and aromas in your wine to something more like wet cardboard or wet dog (chlorinated pool, if you ask me). Cork taint happens when fungus comes in contact with chlorine-based chemicals used in wood (cork is wood after-all) production. Cork taint isn't noticeable until after you open a bottle.
Natural cork is also susceptible to drying out and shrinking, rendering the wine vulnerable to air and oxidation and premature aging and loss of yumminess.
And for that reason, the industry has sought cork alternatives...
Cork has some competition now… and is only used in about 70% of the wine bottles on the market. Still, if you ask me, cork still has the best game in town for age-worthy wines and even the best alternative cited below, is a cork-derivative.
- Synthetic corks: these are made of polyethylene and they let a significant amount of oxygen in the bottle to interact with the wine, aging it quickly. Even when the seal is very tight, there is significant oxygen intrusion. Wines sealed with a synthetic cork are meant to drink right away!
- Screw caps: coated aluminum caps create a near perfect seal (if your aim is to keep oxygen OUT) due to their very tight closure. This has the drawback of creating a reductive environment that won’t permit the wine to soften over time, but will preserve it very well. Australia uses almost exclusively screw caps.
- Vino Seal: a glass stopper that creates a perfect seal, similar in pros/cons to screw caps.
- DIAM: made from small pieces of natural cork that have been glued together, DIAM relies on a complex and patented process to “clean” the cork particles of all TCA. All the benefits of natural cork, without the TCA drawbacks! My personal favorite!
Want to learn how to best preserve your wine after opening it and prevent the effects of oxygen? Read my post on wine preservation systems.
What do you think of cork closures vs screw caps and other products? Pop your thought in the comments section!