The debate has been raging for decades: cork or screw cap? If cork, wooden or plastic? If wooden, natural (whole piece) or technical (agglomerate)?
According to Peter Godden of the Australian Wine Research Institute, “Closure choice is more significant than terroir in shaping the flavour of wine.”
Cork’s cellular structure makes it elastic enough to insert in the neck of a bottle. Once there, it creates a tight seal, but it is also easy to remove. As a wine stopper, it is perfect.
Almost.
In the 1980s, a particularly nasty wine taint was connected to the chemical compound trichloroanisole. This compound is created when fungi or bacteria found in the cork forest come in contact with pesticides, preservatives or chlorine, like that used at cork-making facilities. The compound is highly volatile, and can be detected by the human nose at concentrations as low as four parts per trillion. It leaves wine stripped of its aromas, smelling instead like mouldy newspapers or the neighbour’s wet dog.
One in 10 bottles of wine, it was estimated in the late ’80s, was tainted by trichloroanisole. This was terrifying for wine producers, some of whom had to withdraw entire vintages of product from the market.
The loss of faith in corks built a market for alternatives such as plastic stoppers, but synthetics can’t create a cork-like seal without being impossible to remove from the bottle.
The screw cap has been quickly evolving since the trichloroanisole days of the 1980s. It creates an effective seal, is easy to remove, and although the bottling equipment is pricey, the aluminum stopper itself is much cheaper than cork.
Made from aluminum with a sealing polyethylene disc, the screw cap is not as porous as cork. Eliminating the oxygen transfer to wine risks the development of a rubbery aroma that happens when wine is stored long-term in an anaerobic environment.
The closures debate centres around a long-held belief that oxygen slowly travels through cork, developing wine into a balanced and elegant beverage.
It is, however, extremely difficult to determine whether there is, in fact, such an oxygen transfer, or, for that matter, what is happening to wine while it is aging, and therefore whether this oxygen transfer is even important.
Blind taste tests of wine aged under screw cap have revealed wine that is fresh tasting, with prominent fruit character that generally falls away when aged under cork. However, screw caps have not been around long enough to age wine longer than 30 years.
Since most of the wine we buy is drunk within five years of its bottling date, screw caps will serve us just fine 99 per cent of the time.
The cork industry, for example, is celebrated for its ecological importance and the economic and cultural role it plays for rural families on the Iberian Peninsula, where most of the world’s cork is grown.
To regain consumers’ confidence, the cork industry has been cleaning up its act. The Cork Quality Council ran 25,000 tests in 2013, and found an 80 per cent reduction in cork taint, with about one in 100 bottles showing perceptible trichloroanisole.
(via TheChroniclHerald)
