Turn of the screwcap

The future of wine bottle closures is getting clearer (to me). The future of wine bottle closures is screw caps.

screw capWine drinkers cannot have helped but notice that many winemakers make the leap from corks in favour of screwcap closures. Some wine lovers even rant that corks should be abandoned.

A series of trials had been undertaken by both the University of Burgundy (1960s) and the Australian Wine Research Institute (1970s) and consecutive tastings proved that screwcaps were indeed a viable alternative to natural cork.

For instance, Stelvin is the best-known brand of screwcaps and it is used on Taylors Cabernets.

“No other industry in the world accepts the type of product failure experienced using cork” says George Fistonich of New Zealand screwcap pioneer Villa Maria . Fistonich has been standing firm and all Villa Maria bottles are screwcapped. New Zealand producers have followed and have started a so-called Screwcap Wine Seal Initiative
The n

Screwcap Initiative gets vocal on the radio

In July 2007 an advertising campaign started on the NZ radio. It was embarked upon by the Screwcap Initiative. It has high profile winemakers talking in favour of their preferred wine bottle closure. Wine maker Michael Brajkovich of Kumeu River Wines in Auckland is one of them.

In the advertisement he says, “We were one of the first to export wine in a
screwcap wine bottle. The Old World wine trade didn’t like the idea – at first, they liked
the romance of the cork. But a few of us New World winemakers knew it fixed the problem ofcork taint and once the public twigged to it, it was their seal of quality. It’s another
example of New Zealanders going with what works for us and then finding out that the rest
of the world agrees.”

The advertisement is backed by New Zealand Trade and Enterprise and their website www.exportyear.co.nz. “We are right behind the exporters,” says a spokesperson.

Business demand

Chris Hatcher is the chief winemaker at Wolf Blass, Australia. In 2000 he said that their British distributor had asked that the entire next shipment of Annie’s Lane wines be Stelvin-sealed. Now Wolf Blass bottle some of their super-premium Platinum reds under Stelvin. Henschke, Australia, started screwcap bottling with their Keyneton 1995.

In the USA the Bonny Doon winery has championed Stelvin and has set up a Death of the Cork website. It should be added that an extra incentive for the change is that wine company bean counters also love screwcaps as they are cheaper than corks.

In a similar vein, wine critics now mention whether wines they review use screwcaps and restaurant wine lists follow. Consumer acceptance will grow accordingly. What was once a trickle will become a flood — in time.

A new book on the topic of wine closures is due this October. It is entitled ‘TO CORK OR NOT TO CORK: Tradition, Romance, Science, and the Battle for the Wine Bottle’, by George M. Taber, the author of ‘Judgment of Paris’ (Scribner, 2005). A preview of the book is this good-looking fact sheet on wine closures (PDF) (4 MB).

Cork used to be useful

Cork material is a subset of generic cork tissue, harvested for commercial use primarily from the Cork Oak tree, Quercus suber, with Portugal producing 50% of cork worldwide. Cork's elasticity combined with its near-impermeability makes it suitable as a material for bottle stoppers, especially for wine bottles. Cork stoppers represent about 60% of all cork based production. Many cheaper brands have switched to lower quality cork, synthetic plastic stoppers, screwcaps, or other closures. However, plastic Corks were certainly revolutionary in the 17th century when British ale and French champagne makers started to use cork stoppers instead of traditional closures made of hemp soaked in oil. That innovation certainly improved the quality of wines greatly and without it the development of champagne would have been impossible. But in the age of the microchip we are still using the archaic and risky technology of stoppers made from oak bark.

Cork taint

Why risky? Depending on whom you talk to cork taint (TCA) affects maybe five per cent of bottles, making them unpalatable. Yet, strangely, it has taken more than three centuries for winemakers and consumers to grow tired of wines that are diminished in quality due to this taint and to other problems such as unwanted cork flavours, leakage, cork deterioration and so forth. (For example, the renowned Penfolds Wine Clinics’ main focus is the replacement of dodgy corks).

Screwcap benefits

Screwcaps on the other hand are taint free and impermeable.

No cork taint

Everyone you ask will give you a different answer, but the general consensus from the trade is that between 5-15% of wine is adversely affected by 2,4,6 trichloroanisole. This can occur simply when chlorine is used to wash the cork bark or, more worryingly, it can be due to a contamination of the trees themselves due to the use of organic pesticides which contain chlorine and in this case, affect several harvests.

No more sporadic oxidation

The ideal closure should provide an air tight seal to the wine bottle. A good quality cork is a perfect closure, however, as with all natural products, quality variations mean that “random oxidation” has become the second biggest problem linked to natural corks.

“Driven” closures – whether they are natural or synthetic – need good elasticity in order to fill the gaps and irregularities within the bottle neck. In addition to this, natural corks also contain pits, cracks or insect holes and these create a weakness within the seal that can lead to leakage and oxidation.

Traditionalist criticise screwcaps saying that they are not romantic, however, this industrially-produced closure has the advantage of being more consistent identical, therefore making bottle variation a thing of the past.

Screwcaps also seal from around the outside of the bottle, therefore imperfections within the bottle neck are immaterial and the pressure (approx. 160kg) exerted on the head of the screwcap during bottling ensures that it is totally airtight.

Screwcaps avoid flavour modification, including scalping

Cork is a natural product, therefore, it is inevitable that it will impart some level of taste on the wine to a lesser or greater degree.

As John Belsham of Foxes Island and also current NZSCI president says, “We ran a very simple trial of putting corks into glasses of acidified water. There was a varying degree of colour and flavour taint in all glasses – all except one – the glass containing no cork.”

Screwcaps are totally neutral and therefore do not modify the wine in any way, allowing it to retain the original characteristics and age uniformly.

AWRI research has discovered that the TDN flavour molecule – which gives a kerosene type flavour to white wines – is totally absorbed by plastic closures and partially absorbed by natural cork. This is known as flavour scalping and according to the AWRI, there is no evidence of flavour absorption from screwcaps and this therefore explains why they are so well suited to delicate, aromatic wines such as Rieslings.

Young taste

“Screwcaps have shown wines that are brighter, clearer and more focused. Fruit and mineral characters shine through better than before” says Ken Canaiolo Engebretsen, President of the Norwegian Sommelier Association.

Aging with screwcaps

To test their longevity a number of wine companies (notably Yalumba) have bottled wines under both screwcaps and cork over the last few decades. Comparative tastings of these museum wines indicate that Stelvin bottled wines are fresher, cleaner and retain better colour than examples of the same wine under cork. There are criticisms that screwcaps seal too well and can create reductive characters in wines. This is less true today and should only concern wines that you keep a few years.

Cork is doomed

The list of winemakers actively supporting screwcap is growing. A recent example of conversion is that of a well-known and well-regarded winery in Long Island, NY. It’s Paumanok Vineyards.

For near-term wine the days of cork as a closure are numbered.

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2 Responses to “Turn of the screwcap”

  1. edward says:

    Estelle,

    I hope you’re right, I’m a fan of screwcaps, but I wonder if there is a natural level of resistance.

    In Australia, which has been an early adopter, and where over 70% of whites and perhaps 50% or reds are sealed with screwcaps, there seems to be a slow down.

    Part of the reason, is alternatives to natural cork, like Diam, which is taint free and appealing to the traditionalists.

    Also there is a hard line who refuse to budge. They argue that longevity has only been well and widely demonstrated for cork (even though there is a rate of taint, oxidation etc).

    It’s hard to see classed Bordeaux moving to screwcap for instance for this very reason. . .

    Cheers,

  2. Susan Jacobs says:

    I agree with all the criticisms of cork. Nevertheless, the Stelvin closure is not without problems. Within the last year I have encountered two screwtop bottles which had leaked. One was clearly dented. The other had no visible damage.