The closure debate has always been all about wine quality and how well cork alternatives deal with the problem of cork taint. But as climate change climbs higher up the media agenda, environmental concerns are further warming up this already hot topic.
The Carbon Trust, which helps businesses cut carbon emissions, says environmental concerns are a factor in more than 50 per cent of consumers' buying decisions.
Closure companies are working hard to position different types of closures as greener than others. Oeneo Bouchage, which produces cork granule-based Diam as well as a screwcap, which it launched in 2005, has commissioned work comparing the carbon footprints of natural cork with its own Diam and screwcap.
Natural cork had by far the lowest carbon impact, nearly half that of Diam
and nearly 4.5 times smaller than screwcap.
But the Waste & Recycling Action Programme favours screwcaps
because lighter-weight glass bottles can support screwcap better than cork.
The biggest cork manufacturer, Amorim, has been working on a sustainability study of its business with consulting firm PricewaterhouseCoopers to undertake a sustainability study of its business, looking at the financial, environmental and social issues of sustainability, as well as carbon footprinting.
The Mediterranean cork oak forests are a case study in sustainability. The Montados region of southern Portugal and the Dehesas of Spain are environmentally and socially valuable, if vulnerable, ecosystems. They help fix organic matter and reduce soil erosion, they slow the advance of desertification, and they support low density livestock and farming communities.
But they need to make money to survive, and cork stoppers for drinks provide most of the income .
Amorim's communications director, Carlos de Jesus, says the PWC study showed that in 2006, 4.8 million tonnes of carbon dioxide were sequestered by Portuguese cork forest ecosystems.
"This has a positive impact at the beginning of the chain," he says. "We use cork dust as fuel. Amorim further diminishes its carbon dioxide impact by using renewable resources for nearly 50 per cent of our cork energy needs."
But he adds: "All of this cannot be seen as an excuse to change course from creating better, more efficacious stoppers."
The Forest Stewardship Council promotes and polices sustainability in forestry management around the world, and has recently been developing management standards for cork oak forests. So far only a tiny part of more than 2 million hectares of cork oak forests has been certified, but it's a start. And the first wine to be stoppered with FSC-accredited corks is now available from UK agent
South African wine range African Dawn features the big five endangered animals - elephant, rhino, lion, leopard and water buffalo - on its labels. The wine is made by Rooiberg Winery as part of Wines of South Africa's Biodiversity & Wine initiative, the corks and paper labels come from certified sustainable sources, and a donation from every bottle bought goes to the WWF.
Screwcaps gain fans
Despite cork sitting atop the environmental high ground, a recent OLN poll of wine suppliers found screwcaps gaining share in the UK wine market. In April a Wine Intelligence report on closures found that three-quarters of regular wine drinkers find screwcap acceptable - 25 per cent more than three years before. But cork has not lost popularity - nearly all consumers find natural cork an acceptable closure, a view virtually unchanged from three years ago.
Thresher Group wine buyer Helen McEvoy says: "With New Zealand wines commanding a far higher than average price, the message is getting through to consumers that screwcaps are an acceptable form of closure on wine. Plastic corks are appreciated
for removing the risk of cork taint, but suffer from
lack of aesthetics and a negative environmental image.
"In general, the more wine knowledge a customer has the greater their acceptance of different closures. Outdoor drinking has driven acceptance of screwcaps as these are easily opened without the need for a corkscrew. Natural cork is the preferred closure for those opening wine for a special occasion."
Stephen Crosland, associate purchasing director at Tanners, adds: "I think our customers mostly accept that screwcap is the way forward. Many of our trade customers now demand it for house wine level due to ease of opening bottles."
Oxygen and reduction
But, overall, buyers say that different closure types barely affect their sales.
Sainsbury's beers, wines and spirits quality manager Howard Winn says: "Closure choice is a minor aspect in selection of wines by our customers, coming a long way behind wine style, country, colour and price. Our customers complain when they are dissatisfied about a wine for any reason, so always the first concern is the quality of the wine over and above how it is closed."
When it comes to understanding what happens to wine once it's bottled, we're still at an embryonic stage, but discussion is heating up about the oxygen permeability of closures, and reduction issues. How much oxygen is good for wine development over six months or 60 years? How little is so little that it risks giving the wine reductive notes?
Most closure manufacturers have developed a range of closures with different oxygen transmission rates, depending on how long a shelf-life the wine is expected to have.
Nomacorc offers three different types already, and will launch a fourth option, Premium, which has an even lower OTR, later this year.
Chief marketing officer Malcolm Thomson says: "There is huge interest in Europe." He adds that the stopper aims to have a shelf-life of at least five years, depending on what type of wine goes into the bottle.
Oeneo Bouchage is also working on closures with different OTRs. Sales director Dean Banister says: "At the moment we offer two OTRs. In the next six months we'll have four. We're creating a range so customers can choose a closure to suit their wines."
Too little oxygen can leave wine with reductive characters such as rotten eggs, garlic, cabbage and onion, which have rightly or wrongly been linked to screwcaps.
Screwcap manufacturer UCP has linked up with a major liner manufacturer and Pascal Chatonnet's Excell Laboratories to run some proper trials into the phenomenon. Account director George Thomson says: "We've laid down some tests and, over next 12 months, maybe longer, we hope to understand how taste changes in different types of wines. We're testing both white and red wines to find which are more sensitive to reduction, and which are less sensitive. We're testing different linings of screwcap, Nomacorc Classic and natural cork."
Alcan Packaging Capsules, which makes market-leading screwcap Stelvin, is also on the development trail. Commercial and marketing director Bruno de Saizieu says: "We are developing a new range of liners. We're working with lower and higher OTRs. We expect to do trials with customers, worldwide, in 2008."
To complicate things, we're learning that not all reduced characters are faults. Some volatile sulphur compounds - which come from yeast fermentation and are in all wines - contribute positively to what we understand as varietal flavour : passion fruit, gooseberry, tomato leaf and blackcurrant, for example, are VSCs typical of the varietal make-up of Sauvignon Blanc.
It's speculated that reduction issues are appearing now as we combine reductive winemaking techniques - such as refrigeration, avoidance of oxygen from the point of harvest, inert gas flushing and blanketing - with really tight closure seals. It's suggested that a stopper which breathes a minuscule amount might remove some potential lurking reductive characters. But closures don't differentiate - they would remove "good" VSCs as well as the "bad" reductive-odour faults. It is hoped trials with different OTRs might offer more control.
The cork debate has two new fronts: oxygen and environment. Expect the environmental angle to heat up, and watch out for consumers basing decisions on such factors. But it is still the scientific developments in minutiae that drive technical performance enhancements at the sharp end of the bottle.
For the trade, the closure debate has always focused on the technical side - how to eliminate cork taint and keep the liquid in our bottles at its best. But what about the emotional side of the debate? As consumers grow more and more keen on screwcap, are there still some who cling to the ceremony of opening a bottle of wine with a corkscrew?
Jim Helsby, of the York Beer & Wine Shop, says: "I probably felt that way myself about four or five years ago, when the idea of screwtops and Stelvin closures came in - I felt an emotional, instinctive gut reaction that this is all wrong. But having used them
I don't have a problem now."
Stuart McLeod, of McLeod's in Louth, Lincolnshire, agrees. "It started off that way, but now they are beginning to like screwcaps - it's easy to access and there is no detriment to the wine whatsoever.
"When you get into a £12-14 bottle there is still a bit of hesitation, but not much."
"It's a price point issue," says Ben Furst, of the Sussex Wine Company in Eastbourne. "Up to £10 I would say very few people have problems any more, at least from our clients, and I think the general consensus - and I agree with it - is that I would prefer screwcap to plastic corks, which are a pain and you can't get them back in the bottle. When it comes to the more quality end, £10-plus, people still want to see corks in general."
Sainsbury's BWS quality manager Howard Winn says: "When we get feedback it is normally the emotive response rather than that associated with wine quality, and is often initiated by other vested interests. The closure debate is a technical issue - get the closure right and there is no debate."