Cork and TCA: the facts
TCA (2,4,6-trichloroanisole) is a chemical compound created when natural fungi come into contact with chlorides (specifically 2,4,6-trichlorophenol or TCP) which are found in bleach, other fungicides and pesticides.
As well as cork, TCA can attach to wood, cardboard and plastics – including the linings of screwcaps and glass closures.
TCA does not travel through cork. It can only be transferred to wine if it comes into direct contact with it.
You can sometimes improve a corked wine by pouring it into a jug lined with plastic food wrap for several minutes, as the polyethylene in the wrap attracts the TCA away from the wine.
According to research published in the Journal of Agricultural and Food Chemistry, the air chamber, or head space, in a well-closed bottle of wine contains such high humidity that there’s no need to store the bottle on its side: the cork will not dry out (unless it has been inserted defectively).
Cork stoppers do not allow air to pass from the outside of the bottle to the inside. A cork contains around 800 million cells, each containing a minuscule amount of oxygen. When a cork stopper is compressed to seal a wine bottle, oxygen is forced out of the bottom of the cork and into the wine.
When a cork is said to ‘allow a wine to breathe’, it refers to the small amount of oxygen that remains within the lower cells of the stopper and will be released naturally into the wine within six to eight months of bottling.