Since the discovery of cork's fantastic elasticity, it can be compressed into the neck of a container and will expand to seal the container, cork has been the preferred choice of closure for wine bottles. Unfortunately along with the discovery of cork's great elasticity came the realisation that when the cork bark was harvested and stacked to dry, it was very susceptible to a bacterial infection which imparted into the cork a chemical called trichloroanisole (TCA).
It's worth noting that the concentration of a compound is not necessarily proportional to its intensity. Minuscule amounts of TCA (between 1 and 5 parts per trillion) can be easily detected - about a teaspoon in a swimming pool of water would be overpowering. There is a wonderful scene in the comedy series Fawlty Towers where Basil Fawlty, played by John Cleese, is explaining to an irate customer that the wine couldn't possibly be "corked" as he had just removed the cork from the bottle!
The effect that TCA has on wine even in very small amounts is to strip the fruit flavour and leave a wet cardboard musty character. The worst instance is where the concentration is very low, making the wine just taste dull and the consumer response is, "I wouldn't buy that again."
Because New Zealand is such a small wine producer on world terms, we tended to get cork that had a high incidence of TCA,. In the worst year at a New Zealand wine competition, the percentage of wines rejected because of the wine being "corked" (ruined by TCA) was 14.5%, or 2 bottles in every dozen was ruined by poor cork.
This was the impetus needed to come up with an alternative form of closure - the screw-cap had arrived. As well as keeping the wine perfectly sealed, the screw-cap also allows the bottle to be resealed and the remaining wine kept under refrigeration to be drunk later. I've never actually met anyone who does this but I am reliably told this does take place occasionally.
Screw-cap technology is still developing, already New Zealand has become a world leader in these closures and now even French producers are starting to follow our lead and switch to screw-caps.
It's worth noting that the concentration of a compound is not necessarily proportional to its intensity. Minuscule amounts of TCA (between 1 and 5 parts per trillion) can be easily detected - about a teaspoon in a swimming pool of water would be overpowering. There is a wonderful scene in the comedy series Fawlty Towers where Basil Fawlty, played by John Cleese, is explaining to an irate customer that the wine couldn't possibly be "corked" as he had just removed the cork from the bottle!
The effect that TCA has on wine even in very small amounts is to strip the fruit flavour and leave a wet cardboard musty character. The worst instance is where the concentration is very low, making the wine just taste dull and the consumer response is, "I wouldn't buy that again."
Because New Zealand is such a small wine producer on world terms, we tended to get cork that had a high incidence of TCA,. In the worst year at a New Zealand wine competition, the percentage of wines rejected because of the wine being "corked" (ruined by TCA) was 14.5%, or 2 bottles in every dozen was ruined by poor cork.
This was the impetus needed to come up with an alternative form of closure - the screw-cap had arrived. As well as keeping the wine perfectly sealed, the screw-cap also allows the bottle to be resealed and the remaining wine kept under refrigeration to be drunk later. I've never actually met anyone who does this but I am reliably told this does take place occasionally.
Screw-cap technology is still developing, already New Zealand has become a world leader in these closures and now even French producers are starting to follow our lead and switch to screw-caps.
