28 February 2007    

by Marlene Truter Communications

  • Cork is a proven closure for wine. No other stopper combines cork’s inert nature, flexibility, sealing ability and resilience. Being a natural product, cork is also environmentally friendly, renewable, recyclable and biodegradable.
  • Not all cork stoppers are created equal. Corks are graded by quality in up to seven categories. The quality depends on the raw material used and the production processes adopted by the manufacturer.
  • Different corks are used for fortified, sparkling and still wines.
  • Champagne corks differ from natural cork because they are made from a single moulding of high-quality natural granulated cork, giving it uniform physical and mechanical characteristics. At one end, these corks have two or three discs of fine natural cork. Natural corks are punched whole from the best quality cork bark.
  •  TCA is often referred to as cork taint but this is a misnomer – cork in itself does not affect the wine, but cork may become contaminated with TCA, a contaminant affecting many food and beverage products world-wide.
  • There is no definite research that accurately determines the incidence of TCA taint in corks, although oenological studies suggest that 1-2 % of wines may be  affected by TCA. TCA in wine may be due to contaminated oak barrels or corks, contaminated winery machinery or bottling equipment, airborne moulds in the winery environs and moulds in transport containers or the  cellar.
  • Portugal is the world’s leading cork producer and supplies 54% (more than half) of the world’s corks. Portugal is followed by Spain with 26%, Algeria with 6%, Italy with 5%, Morocco with 4%, Tunisia with 3% and France with 1%.
  • There is enough cork in the cork forests of Portugal to last more than 100 years.
  • Portuguese cork forests are internationally recognised as one of the most successful examples of sustainable agro forestry.
  • Cork trees are not cut down to produce wine corks. The outer bark of the tree is stripped from the tree once every nine years and the bark regenerates itself.
  • The bark of the cork oak is fire resistant protecting the trees form total destruction during fires.
  • A cork tree is in its prime at 80 years of age and can yield 200 kg at a time – enough raw material to produce 25 000 natural wine corks.
  • The world record was set in 1889 by a cork oak in Portugal which yielded no less than 1 755 kg of cork in one stripping.
  • In the 1600s, a French monk called Dom Pérignon, took a giant step towards the modern, most widespread use of cork – as a wine bottle closure.
  • Containers holding sparkling wine was traditionally plugged by wooden stoppers wrapped in olive oil-soaked hemp. Dom Pérignon observed that these stoppers often popped out. He successfully swapped the conical plugs for cork stoppers and cork soon became essential for wine bottling.
  • Cork stoppers arrived in Portugal around 1700. Some 70 years later they were used in cylindrical bottles in Oporto, allowing the wine to mature slowly in a glass receptacle for the first time.
  • The world’s first cork stopper factory opened around 1750, in Anguine, Spain marking the beginning of the industrial application of cork.
  • The spread of mass-produced glass bottles with a uniform neck and opening helped to advance the acceptance of cork stoppers, not just for wine but for a wide range of liquids.
  • The secret to cork’s performance is its unique cell structure, which technology cannot replicate. Cork consists of a honeycomb of tiny cells made from suberin, a complex fatty acid, and filled with an air-like gas. There are on average around 800 million cells in a single wine cork.
  • A cork stopper can be compressed to about half its width without losing any flexibility and it is the only solid that can be compressed in one dimension without increasing in another dimension.
  • The cushion-like cork cells also display what is known as elastic memory. When compressed it constantly tries to return to its original size, thus maintaining a tight seal. This means the cork exerts a very even pressure against the surface of the bottle neck and can compensate for imperfections.
  • Being elastic, cork is also more tolerant than other materials to changes in temperature and pressure.
  • Recent research by the University of Bordeaux has confirmed that natural cork allows a tiny amount of oxygen to permeate into the wine bottle after it has been sealed. This tiny amount of oxygen has an important and beneficial impact on the development of the wine.
  • Not only is cork itself recyclable, biodegradable and renewable, cork forests provide a valuable habitat for birds and other animals and contribute to a mixed agrarian economy that has sustained farmers for many centuries.
  • The cork oak, which is well suited to the hot, arid conditions of southern Portugal, Spain and Northern Africa, helps protect the soil from desertification and is home to many species, including the wild boar and rare birds such as the black stork and the imperial eagle.
  • Portugal’s cork forests are a protected resource, subject to a code of good practice to ensure sustainability of production.
  • Almost nothing is wasted – each part of the cork tree serves an ecological or economic purpose.
  • The world’s oldest cork tree is known as the Whistler Tree.
Vicky Rowe
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