Closures rated

Wine is currently undergoing one of the greatest revolutions since the invention of bottles and subsequent discovery that a tube of cork was capable of keeping the wine in and the air out … well, most of the air out. Screwcaps have all but completely replaced corks in this country (the latest estimate is around 97% of bottles now in screwcap). Most locally made wines can now be opened easily without a corkscrew and sealed just as easily without having to jam the grubby end into the bottle.

Convenience is the obvious benefit but better wine is the major advantage that a closure revolution is bringing to us all. Screwcaps rule although there are now eight different wine closures on retail shelves. Here is my occasionally emotional and unscientific assessment of each in order of preference with a score out of ten points:

Screwcaps – 8 points

When Kiwi winemakers started to switch to screwcaps in 2001 I purchased a case of each of twelve wines. Six bottles of each wine were sealed with corks, the other six with screwcaps. As far as white wine is concerned screwcaps are clearly superior. White wine matures well, lasts longer and is more consistent under screwcap. The jury is still out on red wine but the signs look good. Winemakers have had to change the way they make wine to avoid the development of rubbery off-odours but the problem is now less common.

Technical cork/Diam – 6 points

Most of the “corks” used in this country are made by a process that grinds cork into small chips, treats the chips to remove the chemical that causes cork taint, and then glues the chips into a cork shape. I have never had a corked wine when the bottle had been sealed with a Diam cork. Diam is stiffer than natural cork and probably doesn’t seal the irregular internal bottle neck as well as natural cork but I have only ever found two wines that seemed to have been prematurely oxidised under Diam. Diam is a relatively new closure that needs time to prove it will maintain a good seal without tainting wine.

Glass stopper – 5 points

This German invention seals with a plastic or rubber O-ring. It certainly looks good but my experience with this innovative closure is limited. I wonder whether the limited contact between seal and bottle will provide an effective long-term air-tight seal. Several New Zealand producers are considering using the glass stopper. Time will tell.

Zork – 4 points

Zork is a rather ugly plastic closure that sort of unwinds from the bottle to reveal a plug in the shape of a port bottle stopper. I’ve had little exposure to the seal but wonder whether the compound that it’s made from will taint the wine. I’ve given it a sort of provisional place in my ranking.

Twin top cork – 3 points

Imagine an agglomerate cork (a cork made of glued chips) with a disk of slid cork at each end. The solid cork is designed to isolate the agglomerate cork from the wine which it does to some degree. These were popular with local winemakers who once were unhappy with natural cork but worried about market acceptance of screwcaps. Most now use screwcaps.

Natural cork – 3 points

My score is based on what’s best for the wine, not on wine drinker approval. Natural cork still dominates worldwide although its days must surely be numbered. Work by cork makers has dropped the incidence of cork taint to a still unacceptable level. Corks flavour wine and provide a seal of widely variable efficiency. I hate them. Others are more accepting.

Agglomerate cork – 1 point

Made from cork chips glued together in a cork shape. They often give wine a glue-like flavour after a year in the bottle. Avoid them.

Plastic cork – 1 point

Can give wine a plastic taint. Lack of flexibility tends to make some tight while others can leak air due to variations in internal bottle neck sizes. Safest to avoid them.

A trio of sensual stickies (all sealed with screwcaps)

Lusciously sweet

Villa Maria 2004 Noble Botrytis Selection [375ml) Riesling, Marlborough $39.99

This iconic dessert wine is about as intense and luscious as local Riesling gets. It’s a product of botrytis – a vineyard mould that turns plum grapes into shrivelled super-sweet raisins. Very special wine. – view on

Moderately sweet

Trinity Hill 2007 Gimblett Gravels Noble [375ml) Viognier, Hawke’s Bay $25.00

Great value for a brilliant dessert wine that earned a trophy at the Royal Easter Wine Show. It’s more about the concentrated apricot and quince flavours of Viognier than about the honeyed effects of botrytis. – view on

Demurely sweet

Forrest Estate 2005 Late Harvest Riesling, Marlborough [375ml) $19.00

Classy wine in a medium/sweet style with appealing mineral and citrus flavours. Now showing the benefit of bottle age although there’s plenty of life in it yet. Terrific value at this price. – view on

First published in Your Home and Garden Magazine – May 2008.

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