KEY POINTS:
On midsummer mornings in Portugal's parched interior, the mercury starts at around 30C and keeps rising. Here in the Alentejo, inland from Lisbon, it gets so hot that human activity virtually ceases. As weeks pass with no rain nor respite, locals can do little else but seek shade and wait patiently for the summer to ebb. It's a way of life referred to by other Portuguese as Alentejo time.
These endless plains might well be uninhabited desert were it not for one remarkable specimen: the cork tree. The squat, slow-growing tree can cope with the fine-sand soils and sweltering heat, its umbrella canopy providing shade and sustenance for a thriving undergrowth of herbs and wild flowers and supporting hundreds of species of birds. The result is a surprisingly green landscape studded with small towns - and a cuisine enlivened by rosemary and oregano.
Thousands of lives depend on the cork oak. Yet its bark can be harvested only once every nine years - the first time not until the tree is 25 years old - and then only in moderation. As harvesters like to say: "The tree tells you how far you can go."
The farmer who plants a cork seedling does so not for himself but for his children and grandchildren. Trees will be harvested perhaps 16 times in their 150-200 year lifespan - which makes the patience of the Alentejo people even more understandable. Most plantations, which vary in size from about 30ha to 100ha, are owned by the same families which have farmed them for generations.
The growers explain it like this: "It's not what you have now, but what you are going to leave."
When Apcor, the Portuguese Cork Association, offered to take me into the heart of this region to observe cork manufacturing, I felt uneasy. What welcome would await a visitor from New Zealand, land of the screw cap? As one guidebook says, the Alentejo is one of the poorest regions in Europe. And the traditional tool still brandished by cork harvesters is a lethal-looking axe.
The rise of the screw cap, particularly on new world wines making inroads on old world markets, spread shockwaves of alarm through the cork growing regions of Portugal, Spain, Morocco and Italy. And the screw cap came hard on the heels of a trend towards synthetic stoppers.
But lest you feel guilty as you twist the top off another sauvignon blanc, the news from the Alentejo is that the Portuguese have forgiven us. Far from bearing a grudge, the industry seems almost grateful to New Zealand and Australian wine producers who embraced screw caps in the late-1990s, as a solution to cork taint.
Cork production in Portugal did fall as the use of screw caps spread to California and South Africa and British supermarket chains started insisting on them, but today production is back to levels of a decade ago and the area of land planted in cork trees has increased 3.3 per cent.
Portugal has 730,000ha of cork plantations, mainly in the Alentejo and in the north around the Douro River, where winegrowing is concentrated.
Yet it exports more than it can produce, in some years obtaining more than half the raw product it needs from Spain. The secret to this resurgence lies in the industry's response to competition.
Screw caps made the industry clean up its act, says Marta Sa Pinto, quality control analyst at the Suber Centro cork factory in Pont de Sor.
"There was initial alarm but it really made the industry get its act together," says Pinto, who has a masters degree in biological engineering.
Every aspect of the industry was scrutinised and millions invested in research, new technology and facilities.
Industry codes of practice were introduced and factories wanting to maintain accreditation have manufacturing processes regularly audited.
Today's computerised production line is a world away from the slack standards of the early-1990s. It starts with the removal of defects such as fungus from the bark strips which spend months stacked outside the factory to stabilise the cork.
Once inside the factory the bark is boiled in steam vats to make it flexible and eliminate contaminants, then graded with only the thickest, best quality cork selected for stoppers.
Machines punch out and sand the stoppers smooth (in the old days the stoppers were rounded by hand) before they are washed, dried and graded again, electronically and visually, before branding. Finally they are stored in plastic bags containing sulphur dioxide to prevent microbiological infection.
Pinto says it's possible to trace a cork pulled from a bottle in New Zealand back to the forest it came from and if the wine is tainted, work out at what stage the problem occurred.
This attention to detail has paid off. Incidence of TCA (the chemical which causes cork taint or mustiness in wine) has fallen from around 7 per cent to less than 1 per cent.
Yet with screw caps, says Pinto, 2.2 per cent of bottles are affected by sulphur reduction. (The figure stems from the 2006 International Wine Challenge in London; our winemakers claim 1.7 per cent of New Zealand bottles are affected and that the rate in cork closures is 4.4 per cent).
There's a lot of misinformation about cork, says Pinto. She points out it is only one source of TCA, which can result from practises in the winery or while the wine is aging.
"One New Zealand winery went back to natural cork because it found with screw caps its wine developed a musty aroma."
And, yes, the Portuguese were interested to hear the (hotly disputed) reports that the plastic lining in screw caps is suspected of leaching endocrine disrupters, linked to breast cancer, into wine.
Not that they're making much of it. They don't really need to, with markets expanding as the industry emphasises cork's association with "quality" wine and the snobbery factor. Research shows cork remains the preference of connoisseurs, says Apcor. "The distinctive pop of a wine cork is still a key element of the wine drinking ritual."
While the production-line has gone high-tech, the backbone of the industry remains the growers in regions like the Alentejo and the skilled harvesters who know just how much bark to strip from the tree every nine years without damaging the layer beneath.
Trees are marked with a painted number denoting the year they were last harvested. Even at the first harvest after 25 years, their cork is not of sufficient quality for stoppers. Virgin cork is very irregular explains Nuno Manano, an Apcor technical adviser. Only the third and subsequent harvests produce cork good enough to bottle.
The Government remains very protective of the industry - owners wanting to cut down even dead trees need written permission. It earns the country €900 million ($1.6 billion), about 0.7 per cent of their GDP. Portugal is responsible for 54 per cent of world cork production, the vast majority for stoppers. It's a sustainable industry with no wastage - cork that's not good enough for the bottle is used for cork tiles, gaskets, insulation, sound proofing, cement, clothing, and even in expansion joints in bridges.
And while things may slow down a bit in mid-summer, the industry has been shaken out of its complacency.
"People weren't as proactive as they should have been [in the past]," says Pinto.
"The last few years we realised this is not here forever. Everyone now is concerned about quality. There was a change in mentality and New Zealand had a big part in it."
New Zealand may not currently be a big export market for cork stoppers but that day may not be far off, says Pinto.
"I believe there will come a time when some New Zealand wineries [will] use cork and some countries that only use cork use screw caps."
