How can that wine be any good? It doesn't even have a cork.
With one glance, Casual Kitchen readers know that the above sentence is wrong. The assumption "all good wines have corks" is pure fallacy. In fact, you can more easily argue the exact opposite: if a wine has a cork, the odds are higher that it's actually bad.
Wait... what? How can that be?
In two words, the problem with corked bottles is failure rate. In reality, if a bottle has a cork, there's a non-trivial chance that cork will experience some sort of problem.
Here's why. Depending on where you get your numbers, the wine industry claims a cork failure rate of anywhere from 5% to as high as 15%. And there can be a wide range of types of cork failure: most of the time it takes the form of "cork taint"--an off taste or smell in the wine due to contamination of the cork. If you've ever opened a bottle of wine and smelled a musty smell (some wine writers describe it, appetizingly, as a "wet dog" smell), you've experienced cork taint.
It gets worse, however. Cork stoppers can fail entirely, ruining the wine completely. Sometimes a cork leaks, or fails to protect the wine from oxidization, or worst of all, just breaks apart. This happened to us recently with a depressingly expensive bottle of Chilean sparkling wine: the cork stopper totally failed and wine leaked out of the bottle. It should have been a bottle of bubbly, but this bottle was totally flat. (Confession: we drank it anyway).
Estimates of cork failure vary widely because they depend on how we define failure--and they also depend on wine drinkers' often limited ability to detect cork taint. And to be fair: the cork industry claims a far more optimistic cork failure rate of 1-2%. However, readers should clearly see how it might be in cork producers' economic interests to claim lower failure rates (hey, it's not our corks, it's your crappy wine!), just like it might be in the wine industry's interest to claim higher cork failure rates (hey, it's not our wine, it's your crappy corks!).
Either way, if you make a living selling wine, cork failure is pure disaster. Everybody loses: wine makers, retailers and consumers. And there are better options out there. Plastic cork stoppers, for example, have an extremely low failure rate--well below 1% from the data I've seen. Better still, metal caps, or what you can call "screw-top enclosures" have a preposterously low failure rate--essentially 0%. With these superior alternatives, cork failure rates, even if they're at the low end of the wine industry's estimates, are quite simply intolerable.
In defense of cork
And yet the argument against corks isn't entirely airtight either. Why? Well, for one thing, corks are both renewable and biodegradable, something the cork industry understandably takes great care to emphasize.
However, the biodegradability argument falls down quickly. Think about it: almost all cork products come from small cork-producing regions in Portugal and Spain. If you're a vintner in, say, Chile, New Zealand, Australia, California, South Africa, or any wine-producing region that's any great distance from cork producing regions, you'll actually waste far more energy--and generate a greater carbon footprint--by importing cork than by using some other alternative.
Worst of all however, is the profound environmental waste that occurs if 5-15% of your corked bottles end up going "off" in one way or another. Remember, 15% is one out of every seven bottles. In contrast, literally zero percent of screw-top enclosures fail.
Furthermore, just because something is biodegradable doesn't mean it's better. If you're a conscientious wine producer, you've got to consider the environmental impact of making, aging, bottling and shipping wine that will ultimately fail in the bottle. This is the logic that explains why the entire New Zealand wine industry, after carefully studying the relative benefits of cork versus metal enclosures, transitioned entirely to metal enclosures. For them, it was by far a superior solution.
And of course, looking at cork vs. screw top wine bottles from the standpoint of consumer empowerment, you can easily conclude that consumers also end up paying for wine failures--in the form of higher prices. In other words, consumers get no incremental value from a corked bottle of wine.
Wait. I take that back. There is one advantage of a cork that you just can't get anywhere else: that romantic and satisfying pop! when you open the bottle.
Just cross your fingers and hope the cork didn't fail.
For Further Reading:
1) Wine Flaws: Cork Taint and TCA at The Wine Spectator (be sure to read the comments, many of which are extremely informative)
2) Studies and presentations on cork failure and cork taint issues by the Cork Quality Council, an industry trade group supporting cork suppliers.
3) The Great Cork Debate at Wilson Creek Winery. A good article giving the pros and cons of corks vs other forms of enclosures.
4) Wikipedia's discussion of cork taint.
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