Everything You Ever Wanted To Know About Cork & Cork Taint But Were Afraid To Ask

on 13/12/10 at 1:42 pm


Science of cork taint

The pop of a cork is almost as synonymous with wine as the subsequent pouring, swirling, and slurping.  Sometimes, though, the magic of this familiar ritual is ruined by the revelation that a bottle of wine is … well, “corked.”

There are lots of reasons for cork’s dominance of the wine bottle closure market. It naturally has many physical and chemical properties that make it ideal for sealing a wine bottle, including providing a decent barrier against transmission of oxygen in wine. It’s not without its shortcomings, though, including contributing to bottle variation and, of course, the dreaded cork taint.

Cork as a Natural Product

Cork is harvested from the bark of the cork oak, Quercus suber. Vast forests of cork oak cover millions of acres in the leading cork producing countries of Portugal and Spain, and many animals, including the endangered Iberian lynx, make their homes in the great forests. Unlike most trees, harvesting the bark does not kill cork oak trees, allowing for many cork harvests from a single tree over its lifetime (some trees can be productive for over 200 years), so cork production is widely regarded as a highly sustainable enterprise.

The cellular structure of cork contains a material called suberin, a waxy, complex polymer that contains oil-like carbon chains, polyphenols, glycerol, and other components. Suberin makes the cork impermeable to water and gives it a low gas transmission rate, keeping oxygen out.

Demand for cork is largely driven by demand for cork wine bottle closures, and in recent years alternative closures like synthetic corks  have taken a large chunk out of natural cork’s market share.  Around 70% of the roughly 18 billion bottles of wine produced worldwide are sealed with natural cork, down from 90-95% in the 1990s.

Cork Taint

Since its discovery as the main contributor to cork taint in 1982, much has been written about 2,4,6-trichloroanisole, which is thankfully abbreviated as TCA. Its aroma has many descriptors, including earthy, moldy, and musty, but my favorite is “old library books.”

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