Cork once had the market for wine closures but, in just a few years, new contenders have become serious challengers to its crown. Catherine Dawes reports on a changing sector

Four pallbearers step out of a hearse outside Grand Central Terminal in New York. At the wake, British wine writer Jancis Robinson reads a solemn eulogy. "Oh, Cork. You've had a jolly good run," she says. "The great big supertanker SS Screwcap has set sail, and there will be no turning back." Inside the casket is the figure of a man made out of wine corks. As early as 2002, when this tongue-in-cheek scene played out, wine critics were heralding the death of the traditional cork closure.

In 2003, around 300m screw caps were used on 750ml glass bottles of wine, according to packaging giant Alcan. By 2009, that figure had leapt to more than 17bn. More than half of all bottles of wine sold in Tesco in the UK now have screw caps. Alcan Packaging's Stelvin is the market-leading screw cap and sales and marketing director Bruno de Saizieu says sales are growing in every market.

But the cork industry is fighting back. Portuguese cork manufacturer Amorim insists cork still represents 68-72% of the wine market and is too valuable, in ecological terms, to be discarded. The company has built new factories with high-tech quality testing laboratories and is prepared to challenge the screw caps on price. Carlos de Jesus, the company's director of marketing and communication, says: "The challenge is not to deliver a great cork that costs Ä1.50 for a super premium wine. The challenge is to deliver at 10 times less for the lower price-point wine."

The company, which has its head office in the Porto region of northern Portugal, makes six grades of cork stoppers, from the top-end whole corks to the cheapest stoppers made from granules of cork - the fastest growing type, which can be 50% cheaper than plastic corks. Amorim's best seller is the Twin Top, which has a body of cork granules and a whole cork disc at either end so that both the consumer and the wine ‘see' natural cork.

De Jesus admits that the cork industry had become complacent. But why not? After all, until just over a decade ago it effectively had no competitors. In 1996-7 the first plastic corks hit the market. "At that time, people in the wine industry were fed up with cork and changed over to synthetic. This was the wake-up call the cork industry needed," says de Jesus.

The reason the sector wanted an alternative to traditional corks was largely down to a chemical called trichloroanisole, or TCA. TCA gives wine a mouldy taste, known as cork taint. TCA precursors are found in the soil and in cork bark - if the bark is not treated properly, the chemical will develop.

Countering contamination
Using a screw cap is one way to avoid TCA. "Cork taint affects somewhere between 3% and 7% of bottles. And, of course, one of the benefits of a synthetic closure is that you avoid cork taint," says Alcan Packaging's de Saizieu.

However, Amorim is determined to defeat the TCA problem in natural cork. The company has built new facilities set up to minimise the risks of TCA. The cork bark, once it has been harvested from the cork trees, is removed from the forest as quickly as possible to reduce the risk of soil contamination. The cork is then stored on a sloped concrete floor, which allows water to drain away.

De Jesus explains one of the biggest challenges is that the process of turning cork from bark to bottle stopper involves soaking the bark in hot water. Hot damp conditions are ideal for producing TCA. Amorim has invested in new boiling pits that enable the boiling and drying to be more controlled. All cork bark is carefully inspected for signs of TCA and the corks are put through Amorim's patented ROSA sterilising treatment to prevent TCA occurring.

Amorim has high-tech laboratories where it tests a sample from each batch of corks. And it is hoping, in the future, to test every cork. However, de Jesus says that part of the challenge is that many cork manufacturers are not as thorough as Amorim. He argues that many of the hundreds of cork producers - some of whom are set up "in people's garages" - have a very high failure rate for their corks. "We try to catch faulty corks before they get to vineyards because they damage the reputation of the whole cork industry," says de Jesus.

Alcan argues that using a screw cap also results in more consistent wine, because it is not subject to the natural variations of cork. But corks aren't on the defensive in every respect. Amorim asserts that one of natural cork's greatest strengths is that it allows just the right amount of oxygen to get into the bottle, which allows the wine to mature. Plastic corks often do not form a tight enough seal, allowing too much oxygen in and resulting in a reduced flavour and aroma. Screw caps allow very little oxygen ingress, meaning that the wine may not mature at all.

But de Saizieu is not convinced. "There are two schools of thought in the wine business. One says you need oxygen, the other says you don't," he says. Alcan's Stelvin closures, he says, come with two types of liner. One, made from tin, forms a very tight seal and allows only a tiny amount of oxygen in. The other, made from expanded polyethylene, allows a greater degree of oxygen permeability. "This allows you to choose. If you were bottling a wine for France and Japan, and in France they like more oxygen ingress and in Japan they prefer less, you can use two different Stelvins," he says. He adds that Alcan is also working on new liners that would give more possibilities.

Yet de Jesus insists that if a wine is aged for long periods a screw cap does not allow in enough oxygen. Amorim is currently undertaking research into the effect of oxygen deprivation on wines. It expects to find that decanting a wine before serving does not sufficiently undo the effect of oxygen deprivation over years of being kept under a screw cap.

Yet one of the most obvious advantages of a screw cap from a consumer perspective is that the bottle can be easily opened and resealed. "Particularly for older people, a screw cap is easy to open," says de Saizieu. However, Amorim is investigating expanding the use of bar-top corks - like those used on cognac - on wines and spirits. Traditionally, the phenols in the cork turned white spirits yellow. Amorim has developed a barrier, which is currently at prototype stage, that stops phenols getting into the spirit. "When we get the results of the barrier test we will start actively targeting the spirit market," says de Jesus. He adds that something similar could also be produced for the wine sector.

Natural benefits
Natural cork's trump card is its environmental credentials. According to a life-cycle analysis conducted by Pricewater-houseCoopers, CO2 emissions over the lifecycle of a screw cap are 24 times higher than that of natural cork. The CO2 emissions of a plastic cork are 10 times higher than natural cork. And while aluminium can be recycled, Amorim is instigating schemes to recycle used wine corks into other cork products - such as Birkenstock sandals.

Cork forests are also ecologically important. "Cork trees live in sand so they hold back desertification. The cork forests of north Africa are all that's holding back the desert from advancing further north," says de Jesus. The forests also provide an important habitat for a number of wildlife species. "If the cork industry does not keep going there will be no benefit in maintaining the cork forests. And people will pull them up and plant eucalyptus trees to make paper," adds de Jesus.

De Jesus insists that a natural cork is the only way to retain the romance and occasion of opening a bottle of wine. De Saizieu, meanwhile, is convinced that practicality will win out and the screw cap will continue to take market share. But whether consumers opt for the cork's pop or lean towards the screw cap's click in future remains to be seen.

FIZZ CAPS
Maestro
At the London International Wine Fair in May, Alcan Packaging Capsules launched the world's first metal champagne closure. It is operated by a lever and has cost €1m to develop. Crucially, the closure retains the iconic ‘pop' sound when it is opened. The lever-based Maestro metal closure was launched adorning Champagne Duval-Leroy's Clos des Bouveries 2004 vintage. In development for three years, Alcan is now moving towards large-scale production.

Zork
At the same event, glass packaging supplier Croxsons showed off Zork, a plastic closure for sparkling or still wine developed by Dave Pahl, the Australian entrepreneur behind the Two Dogs alcopop from the late 1990s. The closure is reusable and is opened by a push button which releases the pressure and the seal. It is easily re-sealed and, Pahl argues, is ideal for female fans of sparkling wine who, very often, rely on men to open traditional cork closures.