Strange as it may seem, corks have not always been a permanent fixture in the wine world. As late as the mid-1600s, French vignerons stuffed oil-soaked rags into the necks of their bottles instead.
Cork material is an impermeable, buoyant material that is a prime-subset of the generic cork tissue that is harvested for commercial use primarily from the cork oak, Quercus suber
. Portugal is the largest producer worldwide, making up 50% of production.
The appeal of cork material lies in its cellular structure; it’s easily compressed upon insertion into a bottle neck, and will then subsequently expand to form a tight seal. Given that the diameter of the neck of glass bottles tends to be
inconsistent, this variable contraction and expansion is highly prized.
These days they’re as ubiquitous as the wines they preserve, but it’s still worthwhile to explore the methods and varieties employed.
Your conventional cork comprises of a single piece of bark of about 24mm in diameter. This is 6mm wider than the neck of the average wine bottle, thus ensuring a tight fit.
The cheaper alternative is the agglomerate cork, produced from tiny pieces of chopped cork, bound together by glue. This is a money-saving move – it makes use of otherwise
useless wasted pieces of oak bark. They’re also considerably shorter, allowing for mass production.
The distinctive mushroom cork will be familiar to any Champagne drinker. It is made from three pieces of cork sandwiched together securely. The mushroom shaped head facilitates a good grip when easing the cork out.
Natural cork material has two main drawbacks
: This results in the ‘corked’ flavours that blight wine, producing aromas and flavours reminiscent of soggy cardboard. The use of different pieces of bark to produce agglomerate corks also theoretically increases the risk of fungal contamination.
: The glue used to bond the tiny pieces of cork together to form agglomerate corks have a major
disadvantage, in that they impart a glue-like aroma or taste.
To avoid the above, some producers adopt different approaches:
A cork made of synthetic material. These remove the risk of cork taint entirely.
The screwcap – perhaps the most efficient method of sealing a bottle. This has become widespread across Australia, though some still feel this method is reserved only for cheaper brands.
With both of the above, the biggest concern is that it may affect the ageing of wine. Whilst the matter is not yet concluded, it would seem that screw capped wines age at the same rate as those under the very best corks. Those under an average cork will give the illusion of ageing, but much of this is premature development.