The debate over bottle closures will likely be reinvigorated this week, as Italian authorities have recently approved the use of synthetic corks and screw caps on DOC and DOCG wines (the top 2 quality levels). Here’s the article from Decanter: “Italy approves synthetic closures for DOC, DOCG.”
I thought I’d provide a brief overview of some pros and cons of different bottle closures. Personally, I prefer natural cork or screw cap, but I certainly wouldn’t refuse to buy or drink a wine just because of the closure it uses. A screw cap doesn’t necessarily indicate a bad wine, and a natural cork doesn’t necessarily indicate a good wine. The biggest issues with using an alternative closure on a DOCG wine, like a fine Chianti, will be oxygen and aging potential.
The pros are that natural cork is a renewable resource (it comes from the bark of the cork tree and can be removed without killing the tree) and is biodegradable. It also allows wine to age slowly over time, because its porous nature lets a small amount of oxygen circulate through. This is key for fine wine that is meant to be aged.
The primary con is cork taint (TCA). Depending on which study you believe, cork taint affects between 1% and 7% of all wines that use natural cork. Cork taint creates musty, moldy, or damp cardboard smells in the wine and diminishes the fruit character.
The main reason to use synthetic cork is that the possibility of cork taint is greatly reduced or eliminated. Some also argue that these corks don’t dry out like natural cork, but I’ve read differing opinions on that question.
Oxygen exchange presents a significant issue with synthetic corks. Some types seem to let in more oxygen than natural corks, and others much less. Too much oxygen will age or spoil the wine quickly. Too little, and the wine could suffer from reduction, which is a wine fault that occurs when there’s not enough oxygen present. I usually assume a wine with a synthetic cork is not meant to be held for very long before drinking. The aging issue highlights why the above article is so important, since fine Chiantis are often cellared for a number of years. At the least, the winemakers would need a good understanding of exactly how porous the synthetics are before using them.
Screw caps used to be an indication of a cheap, poor quality wine, but that is changing. Many quality wine producers in Australia and New Zealand are now using these closures on their wines.
The screw cap offers the same protection against cork taint as a synthetic cork, combined with easy opening. Oxygen exchange is an issue here too though. Screw capped wines can become reductive, and of course, a screw cap would not work for a fine wine that’s meant to age.
I’ve only hit the high points on these issues. If you want to get into more detail, here are some resources:
The Wikipedia page on Alternative Wine Closures
“The Carbon Trail of Closures” by Jamie Goode (2007)
(Hint: cork wins)
“Innovative Packaging for the Wine Industry: A Look at Wine Closures” by Denise Gardner (2008)
“Effects of Wine Bottle Closure Type on Consumer Purchase Intent and Price Expectation” by Anna B. Marin and Catherine A. Durham (2007)
(Consumers expect screw capped wines to be cheaper than those with corks.)
“Making Sense of Reduction,” from PinotFile (November, 2011)
“Screwcaps and Reduction in Wine,” reader feedback from JancisRobinson.com (2004)
“Wine Review: Stopping Method Solves Wine Bottle Closure Issues” by Bennet Bodenstein (2012)
(New closure method – the Zork?)
I’d like to know what the price difference is for the wine producer for cork vs. synthetic vs. screw cap. I haven’t found numbers yet, but I’ll post them if I do. And obviously, I need to find out more about this Zork thing!