For only being a few inches long and weighing 0.12 ounces, the cork sure does require a lot of attention to be made… and lately, with the advent of synthetic corks and screw caps, it has also seemed to garner a significant amount of scrutiny.
It is there every time we open a bottle… yet how much attention do we pay to the cork itself, and how much do we know about its composition and just how that little piece of wood came to be in our bottle? Quite little, actually. Which is a pity because the cork tree, the abilities of cork and its harvesting methods are all quite fascinating.
Interesting Facts About Corks
Cork itself is truly a remarkable product. Most know that it is the bark of a cork tree, but few are aware that cork is four times lighter than water, unaffected by air, nearly immune to rot, basically impenetrable by water or air, and completely malleable… although it is also able to withstand 14,000 pounds of pressure per cubic inch, at which point it will revert to its natural shape. Pretty impressive for a piece of wood.
Growing and Harvesting Cork
The cork tree is native to southern Portugal and Spain, and thrives in rocky soil of these regions and in Tunisia, Algeria, Morocco and Sardinia. The majority of the cork used in United States wine comes from Portugal.
A cork tree cannot be harvested until it is 25 years old, and it can only be harvested during the stifling summer months when the tree’s sap is running more freely, which is what allows the bark to be stripped off relatively easy (at least in comparison to the colder months). Once it is stripped, harvesters must wait another nine years until it can be stripped of its bark again.
Harvesters work quickly to strip the bark from the tree using special axes; these sheets of bark are allowed to dry for a year before they are boiled or steamed to increase elasticity, and then flattened and left to again dry. Finally, they are sanitized and cut into bottleneck size using a machine.
The Cause of Cork Taint
The process is surprisingly labor-intensive and the cork’s abilities are impressive . . . but we are all aware of the problems that can arise from the cork. A “corked” wine, which smells like wet newspaper, is the result of the presence of a chemical called TCA (2,4,6 trichloranisole). It was originally thought that TCA came from the chlorine solution which they were washed in; the chlorine actually allowed the fungi inside the cork to grow into mold. The process of washing the corks in chlorine stopped around 1995; however, the “corked” problem has remained. It is now believed that numerous factors can encourage TCA growth including contact with the cardboard boxes which the corks were stored in or contact with the palates used to cart the corks. Even the raw corks themselves have been found to contain the chemical.
Will the issues with corks ever contribute to the end of cork usage in the wine industry? The monetary and phenological benefits of using screw caps or synthetic corks are high, but for centuries the traditional cork has been the only thing separating man from wine. Only time will tell what direction the wine industry takes for its bottle closures.