A cork tree that’s had its trunk shorn of bark looks like an old head on a young body, because the upper trunk and branches are gnarled and wrinkled. As the workers at the Herdade de Vale Ferreira forest farm in the Alentejo forest move to the next tree and make their axe cuts, long strips of bark peel off the trees. After each tree has been peeled, a woman comes along with a paintbrush, and daubs the trunk with a big number to indicate the year it was harvested.
The Quercus suber oak tree is a very old species, having evolved some 15m years ago. It’s perfectly adapted to life on the Iberian peninsula, able to sink roots deep into the sandy soils and regenerate after forest fires. They also trap water in the soil and provide a habitat for rare species like the Iberian lynx and various endangered birds, as well as employment for generations of cork harvesters, known as tiradors. The Q. suber is the only tree able to rebuild its cambium, the layer of new wood. But the cambium is fragile, and so these tiradors are paid a day rate of €100.00 ($119.00), rather than a weight rate. It’s better that they work methodically than take lots of bark and damage the tree.
Everything in a cork forest happens slowly and carefully. Although the cork tree lives for up to 200 years, it’s at least 25 years before it can be harvested, and then only once every nine years or so. At harvest, between 30 kg to 60 kg of cork can be taken, which is between two to six kilos for every dormant year. The cork forests are not high density – there are 80 trees per hectare, on average, with plenty of grass in between.
What this means is that the number of cork forests is necessarily limited. Modern economics dictate that it would be almost impossible to create a cork plantation from scratch, because the period between planting and profit would be too long. Carolina Fino, the owner of the farm, bought it as a going concern five years ago, and says it mostly takes care of itself.
“Sometimes it’s hard to remember that this is agriculture, because it’s wild,” says Frederico Lima Mayer, speaking of the forest. He’s head of operations at Cork Supply, where today’s haul will be heading.
The buyers have checked these trees in advance, cutting small samples before harvest and analysing them in the lab. The price is then set before harvest takes place in May and June. “You have to visit the farm and know the wood,” says Lima Mayer.
Although cork is also used as a building and insulation material, 72% goes into wine bottles. That’s why TCA, the chemical behind cork taint, is such a threat. Not only does it threaten wine, but also this social, economic, and ecological web. In the past decade, new processes have emerged to tackle the taint – but they came quite late, by which time screwcaps and other closures were already well established.
The Cork Supply conference room has a wall of glass which overlooks rows of tables on which are tubs with three corks inside. They are waiting to be checked for TCA by trained sniffers.
Jochen Michalski, president and founder of Cork Supply, says he began the company in California in 1981. “I was purchasing corks from different manufacturers in Portugal and set up a finishing plant in the US,” he began. “The closure market in 1981 was around 150m closures – today it’s 2.4bn. As the business grew considerably, we set up quality control labs.” In 1993, he set up the Portuguese company.
But as the market grew, so did complaints about TCA, particularly from the expanding wine regions of the New World, whose technically-trained winemakers were appalled at losing up to 20% of their wines to cork taint. In 2000, a group of frustrated winemakers in the Clare Valley, Australia, decided to bottle their wines under screw cap, banding together to buy the bottles they needed. Coincidentally, a year later, scientists from the Australian Wine Research Institute released the results of their closure trial, which concluded that the screwcap seal was better than cork. That same year, a group of winemakers founded the New Zealand Screw Cap initiative, to encourage research and share information. By the end of the decade, more than 90% of New Zealand wines were sealed with screwcaps. New Zealand’s premium image made screwcaps more acceptable elsewhere, especially in key markets like the UK and parts of Scandinavia.
Other challengers also saw the market opportunity and moved in, particularly Nomacorc, with their technologically advanced synthetic closures. They spent considerable time and money on researching oxygen ingress, as a way to prove that their closures would not only not damage the wine, but might help to age it at a stable, consistent rate, and in the process raised the oxygen transfer rate (OTR) as an issue that winemakers needed to consider.
The way back
Today, Cork Supply has four different production units in Portugal where they produce and finish their corks. Like the other major cork companies, they have worked hard to overcome the TCA problem. “Where we feel we separate ourselves is we spend a lot of energy and resources in quality control and R&D,” says Michalski. “It’s easy to make 97% of corks. It’s the last 3% where the challenges are.”
One of the initiatives they developed was the DS100 cork, which is ‘dry soaked’, or put in a sterile container to which distilled water is added. The corks are then left for 40 hours, before a trainer sniffer opens the container and tests it. “We were the first in Portugal to come up with these taint free products,” he says.
CEO Isabel Allegro says the company is so confident that DS100 corks are taint free, that it has offered a Bottle Buy Back guarantee since 2011. She says that out of 20m DS100 corks sold, 41 were returned. Of those, only 17 had TCA.
Small changes have made a big difference as well. “In the past you used to see beautiful piles of cork wood in the forest, but we found out it was not beautiful for the cork,” says Michalski. “About ten years ago we started moving it immediately.” Likewise, the old boiling tanks used to clean the wood used to use the same water over and over again, which could spread problems. Today, after boiling and punching into shape, the cork is washed and then passed through the patented INNOCORK system, developed in conjunction with the Instituto Superior Técnico de Lisboa, whereby air flow drives a mixture of water vapour and ethanol around the corks. The steam breaks the bonds between the TCA and the cork, and then the ethanol extracts the TCA. This innovation won Cork Supply the 2007 Sitevi Innovation Medal.
Cork Supply then went on to develop the DS100+, introduced at the London Wine Fair in 2016, which uses gas chromatography combined with Solid Phase Micro Extraction (SPME) to analyse the headspace above each cork and identify any corks that have more than one part per trillion of TCA. “The TCA machines work 24 hours a day,” says Allegro,
She adds that, as of last year, the company now make technical corks. Partly, she said, it was about using their material better, because only 50% is used for corks. Of the other 50%, “35% is byproduct and 15% for Champagnes. The byproduct can be used to granulate and produce technical corks.”
Cork Supply isn’t the only company working to eliminate cork taint, of course. Both MA Silva and Amorim also use versions of gas chromatography technology to identify tainted corks — the entire industry is raising its game.
A new front in the closure war will also open up in 2018, as Cork Supply looks to launch a new product into the territory once occupied exclusively by Nomacorc. Cork Supply plans on using radiation to analyse the internal structure of each cork and assess its permeability, and thereby predict its oxygen transmission rate. “We can send the winemaker a picture of the cork,” says Michalski, adding that Cork Supply is the only company with the technology. “We have discovered that density is not correlated with OTR.” Instead, what’s important is the internal cork pattern. “It’s based on pattern recognition.”
All these initiatives seem to be working. As reported by Reuters, alternative closures accounted for almost half the US market by 2009. Today, cork’s US market share is 60%, while the share price of major cork producer Amorim has risen six-fold. “When you go back 12, 15 years, the forecast for cork was anything but optimistic,” Carlos de Jesus, Amorim marketing director was quoted as saying. “Where we are is a completely different territory from what most people thought possible then.”
Although things are looking up for cork producers, there is one innovation that has them worried – irrigation. According to a Drinks Business report, Amorim is planting 250 ha of cork trees which will be irrigated, in the hopes of reducing the length of the growing cycle. Privately, cork workers in Portugal think this is a bad idea on many fronts. If it works, it will allow new plantations to proliferate and bring down prices and wages. Problems might also arise from giving the trees too easy access to water. After all, these Q. suber oaks have been on the earth for 15m years. They already know how to grow, flourish — and survive.
This article appeared in Issue 4, 2017 of Meininger's Wine Business International.