WHY WE LOVE CORK: Beyond-sustainability-thinking

WHY WE LOVE CORK: Beyond-sustainability-thinking


We think that if more people knew cork's natural history, rooted in the highland forests of the Mediterranean, they might view the artificial screw cap differently. Let's get a feel for why. 


One of the chapters in our Winemaking Manifesto is titled "An Ode To Cork". In it, we provide some context into why we use cork to seal our wines (and why we don't use screw caps), but the cork story is much more layered; we love everything about cork. Since the 1970s, Australia has become one of the biggest supporters of screw caps. Even though, globally, around 60-80% of all wine bottles are sealed with cork, in Australia, it's only approximately 15%. We don't think this is something to be proud of. 


The photos used in this article are from our visit to a cork forest in Sardegna, notice the "stripping" marks on the trees. 


The cork oak forests of the Mediterranean basin (predominantly in Portugal and Spain) are critical ecologies on par with the Amazon in terms of biodiversity measures. These ancient forests, known as "Montados" in Portuguese, support hundreds of endemic species, several critically endangered species that live nowhere else (e.g. the Iberian lynx, the most endangered feline species in the world) and provide direct and vital economic stability to over 100,000 people, according to a WWF report. Since the 13th century, Portugal has protected the majestic cork oaks by law, given their fundamental role in the health and well-being of the community. The cork ecosystems are also a prime example of agroecology - the mutual application of ecological processes and farming - given these are landscapes shaped by the people over hundreds of years of layered sustainable agriculture (forestry, acorn harvest, livestock grazing, etc.). 

Cork oak ("Sobreiro" in Portuguese) is an evergreen oak tree with an average lifespan of 170-200 years. Not touched until they are 25 years old, their bark is harvested in May to August (known as "stripping") using a small, fan-shaped axe and specialised precision; just shallow enough to not harm the tree, just deep enough for adequate thickness. Delicately peeled off the tree in circular sheets, this bark produces "cork". Each tree, after harvest, is marked with white paint and left for at least nine years to re-grow before it is harvested again. Given their long lifespans, it's not uncommon for these trees to be harvested by multiple generations of the same family.

Moreover, the bark becomes smoother after each harvest; the highest quality cork is often linked to the tree's longevity. Given the nature of the harvest, cork production is one of the only forestry techniques that doesn't result in the tree being cut down; the entire cork industry is dependent on (and committed to) the long-term health and vitality of the cork oak trees. The blend of precise harvesting skills and the refined management of these forests means cork harvest is one of the world's highest-paid seasonal farming jobs. 

Then, from a carbon cycle perspective, each year these trees stand tall, more and more carbon is taken out of the atmosphere and pumped into the tree's structure and the soil. Cork forests absorb over 14 million tonnes of C02 yearly, almost as much to offset Papua New Guinea's annual emissions (15.4 million tonnes). A myth has also been circulating about a global cork shortage; however, Portugal (home to around 50% of the world's cork oak forests) can supply the current global cork demand for the next 100 years. There never has been, and nor will there be, a cork shortage. Moreover, given the ecological/social benefits of cork production, large-scale re-forestation programs are underway in the EU (cork forests are, in fact, growing by 4% each year).






Cork closures in wine were used to seal Greek/Roman amphorae thousands of years ago, along with other mediums like beeswax. But when uniformly-shaped glass bottles could be readily produced in the 16th century, corks that fit neatly into the bottles were made. Cork has been the most-used wine bottle closure ever since. 

However, in the 1970s, countries like Australia started looking for cork alternatives, given "cork taint". Cork taint is an unpleasant-tasting chemical compound made by fungi living in the air pockets of cork (cork is 90% air, which is why it's an excellent natural insulative/acoustic material as well) called trichloroanisole (TCA). Wines tainted with TCA have a distinctively "corked" taste (musty, mouldy). However, cork is not the only source of TCA (it's a naturally occurring chemical). Other taints - triboromoanisoll (TBA) and brettanomycaes - are common and do not come from cork. 

Nevertheless, with industrialism came the invention of the synthetic plastic/metal screw cap (no cork taint), and people started trading convenience with social/ecological outcomes. Nowadays, though, cork taint from good quality cork occurs less than ever. Amorim, our cork supplier, has developed a natural pre-processing technique (pressure, temperature, pure water and a bit of time) that separates the TCA from the cork. Good quality, well-produced cork is now reliably free of TCA. This is why, in this day and age, cork has never been better to use. 

(Side note: For those interested in the entire process from bark to cork stopper, Amorim has a comprehensive step-by-step guide into cork production - take a look HERE)

What's more, Amorim has recently invested in multiple third-party audits into the sustainability of cork production from an emissions point of view. Compared to an aluminium screw cap, which emits 37g of carbon on average, the cork closure we use for Minimum (a single piece of oak punched out of the bark) sequesters 300g of carbon on average. A screw cap is carbon positive; a cork is actually carbon-negative. This allowed Amorim to supply Minimum with a detailed carbon audit from our cork purchases for 2022. Amazingly, we sequestered 28.71 tonnes of carbon by using cork, which offsets around 1/3 of our total carbon emissions for 2022! 

It gets better as well if you consider a wine cork - unlike a screw cap - is compostable (I mean, it's just bark = you can pop them in your compost, the worms love them) or reusable/recyclable (you can recycle cork into other products like insulation, a common practice in the EU). At Minimum, we use a high-quality cork punched out of a single stretch of bark (no glues = compostable or reusable). However, you can get cork stoppers that are tiny bits of cork glued together (these are very common, but they aren't biodegradable because of the glues). If you open a bottle of wine under a cork and the cork looks like a piece of wood - that's because it probably is. 

And let's be honest, that's extraordinary; a piece of bark from a tree in Portugal used to protect a wine in Australia, which is eventually put in the compost to slowly decompose back into the soil. That's the lifecycle of something living. 

That's why we use cork.