Do you look for wines sealed with a natural cork? Or do you go out of your way to buy screwcapped wines? How do you feel about synthetic (plastic) corks? A battle is being waged in the world of wine: a fight to find the perfect wine bottle closure.
Cork has, for centuries, been the closure of choice for wines, from the cheapest plonk to the grandest classed growths. But cork has a problem: cork taint. If a wine suffers from cork taint, you say the wine is corked, or corky. By the way, this has nothing to do with little bits of cork floating in your glass: just hoik those out and the wine will be fine.
Cork taint is something much more serious, caused by a substance known as TCA. TCA can get into natural corks during the process of turning the bark of the cork oak into stoppers that can be put into a bottle of wine – there is still debate about how exactly the TCA occurs. What we do know is that humans are very sensitive to TCA and can detect it in tiny quantities (just a few parts per million).
What does TCA do to a wine? First of all, there is no health implication from drinking corked wine – it’s all to do with the effect on the taste and smell of the wine. The effect on the wine depends on how corked it is: at one end of the spectrum the wine will smell damp and musty, as if a bit of rotten wood had been left floating in the bottle. The taste is unpleasant: musty and rotten tasting, with no fruit flavour. At the other end of the spectrum, low level taint can have a small but pernicious effect: the wine just does not have the fresh, fruity aromas and taste that it should have. This is what drives winemakers and wine merchants crazy about it: if you know what the wine should taste like, you may spot that the bottle you’ve got has low level cork taint and put it aside to return for a refund. If you don’t know it, then you might just think, “Didn’t think much of that wine, I won’t bother trying that again.” In other words, cork taint can damage the reputation of a wine and it is out of the control of the winemaker and retailer.
How often do corked bottles of wine come along? It’s hard to find definitive figures, but estimates vary between 1 in 20 bottles to 1 in 10. Wine makers, frustrated at the cork industry’s seeming inability to correct the problem, turned to alternatives: hence the arrival of synthetic corks and screwcaps.
Synthetic corks are made of plastic and are designed to mimic the look and effect of cork, but without the taint. The trouble is, they’re not very good at the job: plastics just can’t mould to the shaped of the bottle neck in the same way as cork, with the result that the seal is not as good as it should be. What this means for the wine is that, as air seeps into the bottle, the wine can start to oxidise: it won’t taste as fresh and lively as it should. Sound familiar? Plastic corks may not cause taint, but they are certainly not the perfect bottle stopper. However, research is continuing in an effort to make better synthetic corks and the risks of oxidation are lower if the wine is in bottle for a short time. It’s rare to find any wine over about £10 a bottle with one of these corks, which is a sign that winemakers are not (or not yet) convinced that these things are good quality. Personally, I don’t like synthetic corks: they’re hard to get out of the bottle, all but impossible to get back in again – and I hate the way you often don’t know it’s synthetic until you’ve taken the foil off the top of the bottle.
If you shop for wine in Tesco’s, you probably have a fair bit of experience of screwcapped wines. A couple of years or so ago, the supermarket decided to take a stand and insisted that many of its suppliers use screwcaps, if they wanted to remain suppliers. Presumably Tesco were fed up with the number of returned bottles from their customers (even though the wine suppliers pay for them I understand). As we buy so much of the wine we drink from supermarkets, and from Tesco more than any other supermarket, this has had a dramatic effect on the amount of screwcapped wine we drink. Tesco obviously got the mood of the customer right and we have embraced the screwcap wholeheartedly. Now it’s a struggle to find any New Zealand wine that is not in a screwcap bottle. Many Australian and some South American and South African wines have followed suit – some Bordeaux chateaux have even taken them up – for their white wines rather than their reds. Screwcaps no longer mean “cheap and nasty” when it comes to wine, although they are indeed cheaper to produce than the natural cork.
Screwcaps seem poised to take over the world of wine….well not quite. They may not cause cork taint, but there are reports of other problems, known as “reductive aromas” in the trade. Like cork taint, in its worst form it’s easy to spot (a bad egg, sulphurous smell), but in milder cases it just causes the wine to be, well, not as good as it should be. It looks like we are back where we started!
It seems that there is no single perfect solution to stoppering wine bottles, one that never causes problems. So should we just stick to cork? We shouldn’t forget that using natural cork helps to protect the unique ecosystem of the cork oak forests of southern Spain and Portugal, which are under threat. Also, the carbon footprint of natural cork is far smaller than either synthetic corks or screwcaps. The cork industry has also apparently cleaned up its act, literally, in an effort to eliminate TCA from their corks. Screwcaps and synthetic corks may have won a battle, but cork may yet win the war.