Many Americans still believe screw capped bottles signify lower quality wine. So much so, in fact, that many European and Australian wines that are sold in their region with screw-caps, are bottled with natural cork for the U.S. market. Is there any truth to this conception? Yes and no. While a screw-cap doesn’t universally mean that a wine is low-quality, the stopper can often tell us about the longevity, culture, history, and yes, sometimes the quality, of the wine it seals.
The most popular wine stoppers are cork, screw cap and synthetic cork. Here are a few things that these types of stoppers might tell us about the wine within.
Cork is the world’s most widely used wine closure and has been used to seal bottles of the sweet nectar since the ancient Greeks and Romans. It has earned a place in history and modern day as a traditional closure so it isn’t surprising that a bottle with a natural cork might lend itself more to a romantic, traditional wine. Additionally, thanks to its elasticity, porous surface and air-tight seal, cork allows just a teensy amount of air to interact with the wine. This controlled oxygenization makes cork a great partner for ageworthy wines.
That said, natural cork is, well, natural. And though it is a highly renewable resource, it’s quality isn’t as consistent as it’s availability. Every cork is slightly different, some are more porous than others, which would affect wine quality. Cork is very fragile, it dries out and crumbles with time, so wine bottles must be stored carefully. The process of preparing and sterilizing natural cork exposes it to potential contamination which can taint a wine.
Oh, and cork is expensive. So a wine sealed with a cork is going to be more expensive than a wine sealed with a screw cap, regardless of quality.
Australians are actually to blame for the rise of the aluminum screw cap wine bottle. In the 60’s cork taint was so common it felt like an epidemic, so the screw cap was developed by winery director, Peter Wall, as an alternative. It does the trick. TCA, the taint that affects so many wines under natural cork, is almost nonexistent under screw caps.
Also, because aluminum isn’t porous and the caps seal tight, wine remains relatively oxygen-free under a screw cap and thus can live longer on the shelf and after opening. The product in the bottle remains truer to the day it was first made than a wine under a natural cork. There’s also the added benefit of them being easier to open and generally less expensive, based solely on the cost of their closure.
However, because of that tight seal, screw-capped wines are prone to reduction and have questionable aging ability. Furthermore, whereas natural cork is renewable and biodegradable, aluminum is not. The production process of aluminum negatively impacts the air and water and generates loads of waste. And, while the caps are recyclable, it is suspected that most of them wind up in the trash.
Made from either petroleum-based plastic or plant-based materials, synthetic corks are not prone to TCA taint and provide predictable oxygen transfer rates and a tight, immovable seal. They are highly durable (hooray no cork crumbs in the bottom of your bottle) and they are definitely less expensive to manufacture than cork (and often even screw caps).
Obviously, the environmental impact of a synthetic cork depends on whether it is made from oil-based plastics (not good) or plant-based resources (better). But the most common con of a synthetic cork is that they are a pain to open and even more of a pain to use to re-seal a bottle. The latter might seem like a small issue, but if you can’t properly re-cork an open bottle, your wine isn’t going to last.
A wine’s closure doesn’t say anything concrete about the quality of the wine it encloses, but it can tell you a lot about the wine’s potential, the priorities of the winemaker, and more. So the next time you see a natural cork, screw-cap or synthetic cork, think twice before you judge the wine inside.