Those of us in the wine trade hone our olfactory skills to recognise a wide range of aromas good and bad. Detecting fault in a wine is one of the less appealing aspects of my job, down right uncomfortable if the winemaker is present. Some faults in small measure can actually enhance a wine – VA or volatile acidity can liven things up. When blind tasting for my MW yesteryear – a ‘lifted’ note of ethyl acetate and some acetic acid on the palate might well suggest Italy, which in a modest does was not unpleasant. However when it comes to cork taint, well that’s never going to enhance a wine.
I need to stop here and clear up a mis-conception. There is no cork in a ‘corked’ bottle. So called ‘corked’ wine is suffering from a chemical compound called TCA (2,4,6-Trichloroanisole) which occurs when fungi come into contact with chlorides, which are found in fungicides, pesticides, bleach etc. Once you’ve committed the mouldy smell of TCA to memory you’ll sniff it all over the place – particularly, I find, on cardboard packaging.
The most likely source of TCA in your mouldy smelling wine is the cork… but the cork producers are quick to point out the other culprits for contamination before the wine hits the bottle – these range from oak to filters.
Problem is, natural cork rather sullied its reputation and hence other closures were developed to body swerve the TCA issue, although they come with some problems of their own. Closures can be the cause of problems during storage, as well as when the wines are bring transported. No closure is perfect. You can get reduction (a smoky smell) from the use of screw cap, and plastic can allow oxidation and has iffy sustainability. For that matter TCA can attach to plastic, including the lining of screw caps and glass closures.
The cork industry fought back after years of TCA unhappiness and have invested millions in addressing the situation. The strategy to eliminate TCA begins with the management of cork oak forests and carries through harvesting, ageing and production of the cork. I hope to go out and have a look next year.
These days steam is used to clean the cork. However years of fungicides and herbicides used in the forests is still held in ground and in the trees, which do not start producing bark thick enough for harvesting until they are a staggering 43 years old. And so despite all precautions there is the risk of the natural fungi (and the forests of southern Spain provide an ideal humid environment) coming into contact with chlorides, and despite all efforts no cork could be guaranteed TCA free until the the advent of the electronic nose.
In a ‘Nose off’ the electronic nose would certainly win the day.
In late 2016 the heavy weight cork producer Amorim launched NDtech – an advanced technology to guarantee a cork with non-detectable TCA. Now this is rather clever stuff. The cork goes into a chamber where, as it is heated, it releases volatiles which are analysed by a chromatography machine. A process which takes just 16 seconds per cork. This so called ‘electronic nose’ can detect 0.5 nanograms of TCA per litre, the equivalent of one drop of water in 800 Olympic size swimming pools.
Respect for this ‘Nose’
I’m all for a reliable cork, TCA free cork. This expensive technology is, for now, only used for the top end corks, costing 14-20 cents extra per cork, but it will filter down the chain to your everyday bottle.
In a neat inversion, cork is perhaps the only closure that can prevent TCA from outside the bottle entering the bottle. TCA cannot travel though cork. It’s a great closure. Its elasticity allows it to expand to fill the neck of the bottle making a prefect seal, (no air) while the millions of cells contain microscopic quantities of oxygen which are squeezed into the wine and continue to be released for some months subsequently helping the wine to breath, in other words to evolve.
Moreover there are plenty of sound ecological reasons for the use of cork. If it can be reliable, well then – what’s not to like?