How green is your screwcap?

August 5, 2019

I’ve just come back from a fabulous week in Portugal sponsored by the biggest cork manufacturers in the country – Amorim. We ate far too much, drank far too much and, in the midst of our gastronomic orgies, we actually learnt a lot about cork. I have to say that given the choice between cork and screw-cap for my wine, I would probably choose screw-cap most of the time – it’s quick, it’s easy, I know my wine will be in good condition, I can re-seal it if (heaven forbid) I don’t finish the bottle and to be honest – the majority of wine I drink is young, fresh, fruity and not made to age so screw-cap is the ideal closure.

But cork has been used since ancient times to seal wine, oil, vinegar and for a variety of other uses as well. However, about two decades ago, the quality of wine corks decreased dramatically as technological advances increased, making for much greater production without associated greater quality – we found ways to produce more corks, without actually making them any better. At one time, the industry average for a corked wine (ie one that is affected by trichloroanisole or TCA – an infection which reacts with the flavour esters in a wine and turns it sour) was about 1 in 8 bottles and this gave the screw-cap manufacturers a gap in the market which they have been filling and expanding ever since.

Portugal is the home of cork and has the most cork forests. Once mature, the cork trees get stripped of their bark every nine years or so and the resulting spongy, lightweight planks get borne off to immense factories where they are rigorously cleaned and checked before being made into a variety of different types of corks. Following the quality dip in the 90’s, companies such as Amorim have made huge strides in research and development to the extent where they believe they will be able to guarantee that all their corks are 100% infection-free within the next few years. Certainly, the incidence of an Amorim cork tainting your wine is now less than 1%, a big improvement on previous years.

So cork is back on the playing field from a quality point of view, but the really interesting discovery I made in Portugal is that it is actually leading the field in a couple of other areas as well, most notably sustainability and ‘green-ness’. Did you know that a screw-cap has 24 times the carbon emissions of a cork? Yes, that’s right – 24 times. Astonishing isn’t it? Cork trees absorb around 14 million tonnes of CO2 every year, they rejuvenate themselves after each harvesting and along the way provide invaluable habitats for many indigenous species. Every single bit of cork is used in one form or another – either for wine stoppers, flooring, shoes, gaskets, airplane seats – and the residue is used for fuel, making some of Amorim’s factories virtually self-sufficient in terms of power consumption.

It was fascinating stuff indeed, and not only is cork a greener choice, it may also be actually improving your wine as well if you intend keeping it for any length of time. Cork contains natural polyphenols – tannins and flavenoids – which react with wine and help it mature and change character. Research is currently underway to determine exactly what effect these polyphenols have, but cork-fans would say that it’s only going to tell us what they know already – that wine matures better under cork in the long-term.

I’m not advocating wholesale abandonment of screw-caps – they definitely still have a place for lots of styles of wines – but there certainly is more to cork than meets the eye. As increasing numbers of people care about what they eat and drink and about preserving our planet for future generations, I think that a natural, sustainable closure such as cork is going to be seen in a new light. And on a personal note, anything which helps do away with the ultimate closure abomination – the plastic cork – gets my vote. Go cork!