In our third installment of the greatest changes in drinks since db was launched in July 2002, we consider the importance of the closure debate.
The closure debate has remained heated over the past ten years
Throughout db’s history if there’s one issue which has proved consistently inflammatory, it is how best to seal wine.
Early last decade, New World producers were understandably irate over the high incidence of 2,4,6-trichloroanisole (TCA) in their wines, blamed entirely on faulty corks.
New Zealand turned to screwcaps, where usage increased from 1% in 2001 to 70% by 2004. Indeed, the country can be credited for making the screwcap almost the default closure for aromatic white wines worldwide.
But it wasn’t only the New World that went against cork; a major signal that the traditional closure may be in trouble came with Domaine Laroche’s decision to seal its Chardonnays from the 2001 vintage in Chablis with screwcaps – including its grands crus.
But just how bad was TCA in finished wine (whether from corks or sources such as barrels or storage containers)? Domaine Laroche claimed 10% of their wines were spoiled, while 2004’s International Wine Challenge in the UK had figures showing 4.9% of the 11,000 bottles opened had perceptible TCA taint.
In 2005 a Wine Spectator blind tasting of 2,800 bottles produced a headline-grabbing figure of 7% for wine taint.
Such evidence inspired the invention of various techniques to guarantee TCA-free corks, from steam cleaning to more complex processes, such as supercritical fluid extraction.
At the same time, plastic corks became mainstream.
However, early examples frustrated consumers who couldn’t remove them from corkscrews, and the weak seal between plastic and glass also led to high levels of oxygen ingress after 18 months, as highlighted by an Australian Wine Research Institute survey in 2001.
This was not a problem for naturally elastic cork.
As the level of TCA in wines sealed under cork began to drop, the debate shifted to other properties of the various closures.
OTR studies showed the differences in oxygen permeability in screwcaps, depending on the lining, with Saratin the least permeable
Under particular scrutiny was the oxygen transmission rate (OTR) of screwcaps and natural cork, as well as so-called technical corks, and increasingly sophisticated synthetic closures, particularly from Nomacork.
Soon db was writing not so much about TCA, but OTRs and finally, TPO (total package oxygen), as it became clear that oxygen pick-up during bottling was a crucial part of any potential problems.
Then there were the environmental implications of different closures, and the carbon footprint of a cork versus a screwcap became another area of interest.
Indeed, as db completes its decade reporting on the issues, which it has done extensively with the expert help of Sally Easton MW and Dr Jamie Goode, it’s interesting to note a minor comeback for cork.
Indeed, Peter Gago, head winemaker at Penfold’s, admitted during an event after this year’s London International Wine Fair, that levels of TCA in his wines were down to 1%, or, he explained, the same percentage that are prematurely oxidised due to mechanical damage to screwcaps.