You will probably have noticed that Supermarkets shelves are filling up with more and more screw capped wines. Almost nine in ten wines from New Zealand now arrive in the UK in screw cap bottles – around 12 million bottles a year.
Personally I am not in favour of screw caps and if you want to see an in depth comparison read my blog To Cork or Not to Cork. There have been several adverse reports about them in the press and the www.news.scotsman.com noted that “more than one in 50 screw cap bottles sold in Britain could be tainted because of broken seals or sulphidisation – a chemical reaction caused by excess use of the preservative sulphur dioxide and a lack of oxygen.”
In effect this means that millions of wine bottles which use screw caps instead of traditional corks could be spoiled by a smell of rotten eggs, burning rubber or burnt matches. The findings mean drinkers still risk buying wine which tastes off even though modern screw caps were meant to solve the problem of “corked” bottles.
Around 100 million screw cap bottles of wine a year are sold in the UK and the figure is rising as it becomes a popular alternative to cork.
The www.telegraph.co.uk has reported that the annual International Wine Challenge (IWC) event (which is the world’s biggest wine competition and tests tens of thousands of wines from all over the world including around 9,000 with screw caps and many more with corks) has discovered that while cork taint is on the decline it seems that the problems affecting wines sealed with screw caps have probably been underestimated.
They found that 2.2% of the screw capped wine had been damaged. Faults caused by the latter are mainly a build-up of sulphides. Sulphides exist naturally in wine. When they degrade they produce a compound called a thiol which is what gives sulphur its smell. Although the IWC found 4.4% of cork-closed bottles suffered sulphide problems, corks allow oxygen into the bottle, which desulphides the thiols and stops them smelling, but screw caps do not allow this. Excess use of sulphur dioxide during bottling can exacerbate the problem.
The results could mean problems for shops and restaurants because the smell is much easier for drinkers to spot than TCA – the chemical compound 2,4,6-trichloroanisole which is found in corked wine.
The Scotsman’s wine expert and Master of Wine, Rose Murray Brown says that “detecting a screw-cap wine with too much sulphur is much easier than spotting a “corked” wine . . . but the problem is easier to deal with. If you aerate the wine a little by swilling it around the glass, the smell should disappear.”
She added: “Most retailers have a policy which states that you can return wine that doesn’t smell right, so consumers shouldn’t feel embarrassed about taking it back.”
Although plastic “corks” are available, they are unsuitable for all but the youngest of wines, because they perish after a relatively short time.
Traditionalists love cork, as do environmentalists, because it is natural and has served the wine industry for hundreds of years. It also has a satisfying pop when the bottle is opened. Screw caps, on the other hand, are seen as industrial, cheap and lacking the romance of the old “closure” but they have been hailed as the future because there is supposed to be no danger they will spoil or “taint” the wine.
Maybe its time that the argument between the old and the new was re-examined as obviously screw caps are not living up to their claims.
The real acid test of cork versus the screw cap will happen in 10 years time as Chateau Margaux have laid down two cases of Le Pavillon Rouge (their second wine) under screw cap as an experiment to reveal the truth once and for all.