Extremadura

The region I am visiting is called Extremadura – it is a vast part of the interior of Spain. Wide plains, low mountains, ruined castles and walled cities as far as you can see under a brilliant sky. It nearly looks like the African savannah, with huge, thickly trunked cork trees spaced evenly, with cattle and the famous and delicious pata negra (black footed pigs, which are used to make Jamon Iberico,) pigs feeding in their shade on grass, tubers, mushrooms, and acorns. Here along the border and into Portugal is where most of the corks used in the world are grown. Once it reaches maturity at about 65 years of age, a cork oak can be harvested about every 11 years – the cork harvesters cut around the trunk carefully, and remove the thick bark – all without harming the tree, which then begins to grow back its skin over the next years.

A little background – Corks have been used to close wine (and other) bottles for hundreds of years. They have certain properties that make them ideally suited for this task – they are compressible, but rebound to their original dimensions, allowing them to form a secure seal even in an imperfect bottle neck. They are water tight, but allow small amounts of oxygen through them, allowing wine to oxidatively ‘age.’ They are a renewable resource, and provide nesting habitat for endangered African storks.

At the same time, they have some drawbacks that have been recognized for just as long. As a natural product, each one varies in how much oxygen can be transmitted through it. This means that bottles can vary widely from one to the next, based on too much, or not enough oxygen being available to the wine. Sometimes they leak. Other times, they cause the wine to taste dank, like a root cellar, mushrooms, or wet cardboard. This last symptom is known as ‘cork taint’ and is one of the major issues that the wine industry has been struggling with for years. The main compound responsible for this aroma is called 2,4,6 Trichloranisole, or TCA for short. This compound, along with its related TCB, and others, can affect 3-10% of wines closed with a cork, depending upon who you talk to. The worst part about it is that many consumers do not know about TCA, and when they open a tainted wine, they have to assume that the reason that they do not like the wine is that it was not skillfully or carefully made.

Despite increased awareness and heroic efforts by the cork industry (which has been facing severe competition from artificial corks and screwcaps,) to review and improve their processing controls, analysis and traceability, this problem still exists. Even purchasing the very highest grade, most expensive corks is no guarantee of a solution – although very low grade corks may have increased incidence of problems, at the higher level TCA still exists.

The company that I have travelled to Spain to meet with is called Oeno Closures. They are an offshoot of a traditional cork company that has been working on this problem for a long time. Their approach is novel, and they hold several patents related to a process which produces a closure, called DIAM which is warranted to have TCA levels at below detectable levels in the wine, (less than 0.5ppt with current technology; it is aroma active around about 4 parts per trillion!!)

I have used these closures in the past; hesitantly at first, but the more that I have worked with them, the more I appreciate their good qualities. There is no one best closure for all wines, but this is certainly a great tool to have in hand, and the leap forward that their process represents should spur further effort and research into solving the problem.