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    June 2, 2014

    A Peak Into the World of Cork Production

    I recently returned from a trip to Portugal to visit the cork forests and processing facilities that produce the corks that finish our wines. It was a great experience and a chance to learn about a critical step in the winemaking process that often gets taken for granted.

    When I started my career in the 1990’s, there was a backlash against cork producers due to rates of TCA contamination (cork taint) that seem impossibly high today – reports of sometimes as much as 15% of corks being tainted. Some producers moved to alternative closures such as synthetic corks and screw caps, and the cork industry has had to work hard to regain the trust of their consumers. Now, rates of cork taint have been dramatically reduced due to a chemical-free approach to farming the cork trees, increased sorting of the starting materials, bleaching with peroxide rather than chlorine, the use of steam to remove taint, and much greater quality control of every batch of corks that leaves the factories. Unfortunately, we are still not at the level of absolutely no taint, but the rate of cork taint has been reduced to below 0.5% by many cork producers.

    The cork forests themselves are real treasures. Cork trees need to mature for nine years before the first harvest of their bark, and then can be harvested every nine years after that. The first two harvests (ie 18 years) are not suitable for wine cork production due to the uneven growth of the bark. After the third harvest in the 27th year, the bark can be used to produce cork products of all types, from ground up “agglomerated” corks, to the twin top disks used in sparkling wine production, to corks of varying  lengths and degrees of pitting (factors which are mostly aesthetic considerations). The farmers in Portugal told me that they plant new forests for their grandchildren, and the most common motivation is “because somebody did it for me.” Only 30% of the cork bark that is harvested is of the quality required for use in wine; the remaining 70% is used for other products such as flooring, insulation and even in producing handbags and wallets. The small amount of product that cannot be used for any other purpose is ground up and burned to provide the electricity that runs the factories.

    Cork forests are planted on the upper limit of the Sahara desert in Algeria, Morocco and other North African contries and stretch into southern Portugal and Spain, where they help to prevent erosion and prevent the desertification of a very vulnerable ecosystem. The trees themselves grow in extremely dry conditions, practically in pure sand and rock, and are not irrigated and are often not treated with any chemical fertilizers, pesticides, etc, at all. The cork industry also provides jobs for thousands of people in countries that have been hit hard by the recession. The corks themselves can be recycled into products like shoes, cork boards and more, and here in Wine Country, it’s common to see cork collection bins for this purpose. So, all in all, natural corks are a product that one can really feel good about.

    I do believe that there is a place for alternative closures in the wine world, but for the wines that I produce, I think that natural cork is the best closure because of the enhanced aging due to a limited yet constant exchange of oxygen. Also, natural corks are easy to remove from the bottle, and I am personally drawn to the rich history of its use in winemaking. There is no sound I like better than the satisfying “pop” as a cork is removed from a bottle of wine.

    -Sally Johnson Blum, Winemaker

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