Put a cork in it!

Wednesday, 22 May, 2013
Cathy Marston
Over the years I’ve tried not to get involved in the Cork vs Screwcap debate (although I know I have slipped up from time to time, not least on these pages!), believing that there was little my opinion was going to change and people got far too worked up about it all anyway. 
I will admit that my preference was generally for screwcaps since I loathe that feeling of disappointment you get when your only chilled bottle of wine is corked and you really need a cool, crisp glass of Chenin in a hurry. Also, I keep getting my corkscrews confiscated at airport check-ins or having them stolen by light-fingered winemakers after wine course sessions (mentioning no names Joris……).

So it was a bit of a risk for Amorim, one of the main cork suppliers to the SA wine industry, to invite me to Portugal to go and check out cork production and see what was going on. A tweet from a vehement screwcap fan warned me not to get brainwashed by these Porras and their convincing cork talk, but instead of returning full of hatred for screwcaps and fanatical support for corks, what has happened is that I realize that I have been clinging to outdated prejudices and information and in fact, a lot of what I thought I knew about cork is now untrue. So, without jumping on any kind of propaganda bandwagon, here are a few things that surprised and intrigued me. Perhaps they will you too.

Incidence of cork taint – not traveling from cork to cork. I always believed that cork taint can be transmitted from one affected cork to another, but apparently that is impossible. What can happen is that during the washing process, TCA can be flushed out of one cork and transferred via the water to the rest of the batch. Nowadays you can use steam which reduces the risk of transferring infection and also means the corks dry quicker so reducing humidity and the possibility of fungal growth.

Cork taint – can they get to 100% guarantee of none?
Well, apparently, according to head of R&D at Amorim, Miguel Cabral, the answer is yes. A new machine tests corks individually for TCA and is 100% effective at picking up anything that shouldn’t be there. The problem is that it can only do 4,320 corks a day which is too slow, so they are now working on one which can analyse 10 corks at a time. If any cork taint is picked up, even if it is only be a single cork, the entire batch of 10 is discarded and sent to make flooring. If they can roll this machine out into mass-production, then yes, they will be able to guarantee no TCA taint in an Amorim cork. However….

Responsibility of the winemaker.  This is an interesting area, in particular with reference to the above point. Poor cellar handling and practices can mean that TCA can infect a wine even if it’s sealed with a screwcap or plastic cork. Sometimes winemakers buy corks in bulk to get a better price, store them inadequately in conditions where fungal growth can take place and then blame the suppliers for subsequent cork taint. Equally so, other examples of poor cellar hygiene (failure to wash bottles correctly, contaminated barrels, transport) can also result in spoilage. If the 100% TCA-free guarantee is actually going to come into effect, the conditions under which it will operate will have to be stringent and clear.

There are cork companies and there are cork companies…. For all the checks and procedures a company like Amorim carry out, there are always other, possibly cheaper manufacturers who don’t. Consumers have no idea who makes which corks but we’re quick to blame the cork industry as a whole if our wine is ruined. We also need to remember that many of the wines we are now starting to drink (ie 10 year old reds) are often sealed with corks that haven’t been subject to the new procedures. Just because we had a dodgy cork from a batch made a decade ago is no reason not to put a cork in our wine now.

Polyphenols. This was a fascinating topic and it looks as if there is more interesting information to come. For centuries, people have believed that oxygen penetrates cork and changes the character of wines but this has been conclusively disproved both by science and experience – 168 bottles of 200 year old champagne were recently recovered from the bottom of the Baltic Sea with the wine still in excellent condition.

6% of a natural cork is polyphenols – large, structured molecules which can be tannins, lignins or flavenoids. It is believed that the interaction between these polyphenols and wine is actually what causes development and maturity- experiments have recently been conducted with champagnes where the second fermentation is carried out under cork instead of crown cap. These experiments have now provoked sufficient interest for a PhD study which will start later this year at the University of Bordeaux with the aim of identifying the effects of polyphenols and possibly isolating them. If it can be proved that natural cork really does add something positive to wines which are meant to age, then that could signal big changes to the way we think about closures.

Carbon footprint
. Of all the things I learnt in Portugal, by far the most surprising was the fact that a screw-cap emits 24 times the carbon emissions of a cork. The cork forests can absorb 14 million tonnes of CO2 per year and the cork trees can live up to 200 years old, getting harvested around 15 times during their life with no adverse effects. Cork is very lightweight and can be re-used in a variety of ways – we saw floors, furniture, handbags, train carriages, insulation, gaskets and a host of other uses. Even the tiny cork dust particles are used as fuel meaning that 60% of Amorim’s power costs are provided by cork. As consumers become increasingly concerned about carbon footprints and other environmental issues, this could be a big feather in the cork producers’ caps.

So there you go – a few things I didn’t know. Have I had a change of heart and am I now officially a cork dork? Well, no actually – I’ll probably still pick a convenient screwcap for my next picnic (sorry ozone layer and Amorim), but I do have much more confidence in cork following this eye-opening trip.

There has been plenty of discussion on corks following the results of the Old Mutual Trophy Show with talks of 66% of white wines being corked – I read Michael Fridjohn’s article on Business Day but couldn’t quite work out how that figure was calculated. I do hope the calculation is made clear though, because if it is as scary as it sounds, then clearly the cork industry has much more to do. Perhaps the most positive outcome of the Old Mutual furore would be for a reasoned and informed debate as opposed to knee-jerk reactions and blanket-boycotts of cork. And perhaps it’s also time for journalists to bow out of this debate and leave it to the only people who should be making a choice for their wines – the winemakers.