Corks To Zorks - Closure Options

Natural cork has been used for centuries to seal wine bottles but as technology has improved and “tainted” bottles increased, the controversy surrounding what’s the best closure for wine is heating up.

Cork Taint, as it is often referred as, comes as a result of the presence of the chemical Trichloroanisole or (TCA). The cork industry group APCOR (Associação Portuguesa da Cortiça) in Portugal, cites a study showing a 0.7 – 1.2% taint rate, but a 2005 study by a popular wine magazine showed it to be closer to 7%. That’s a lot of spoiled wine.

 In an attempt to combat this potential for spoilage, a variety of substitutes have been been proposed and now utilized. Let’s review the alternatives:

 Synthetic Corks - Synthetic corks are made from plastic compounds designed to look and "pop" like natural cork, but without the risk of TCA contamination. The US company Nomacorc is the world's largest producer of synthetic corks. Disadvantages of some synthetic corks include difficulty in extracting them from the bottle and difficulty in using the plastic cork to reseal the wine. And some notable wine experts claim that some can also impart a slight chemical flavour to the wine.

Unlike natural corks, many synthetic corks are made from material that is not biodegradable. There are three main production techniques for synthetic wine closures: injection molding, extrusion (mono- and co-) and the Vinova type production, which combines the advantages of both injection molding and extrusion molding. A 2007 study in Bordeaux showed that synthetic cork allowed the highest levels of oxygen permeation in when compared to natural cork and screw caps, offering the lowest protection against oxidation of the wine. I personally find this hard to believe since the darn things are so difficult to pull out in the first place.

Screw Caps - Screw caps or "Stelvin caps" are closures made from tin or aluminum material that threads onto the bottleneck. They are the predominant closure used by New Zealand wineries. This can be attributed in part to the New Zealand screw cap initiative which promotes the use of screw caps instead of cork. Screw caps form a tighter seal and can keep out oxygen for a longer time than cork. These benefits aid in maintaining the wine's overall quality and aging potential.

Glass/Plastic - Vino-Seal is a plastic/glass closure released by Alcoa. Since its introduction into the European market (under the name Vino-Lok) in 2003, over 300 wineries have utilized Vino-Seal. Using a glass stopper with an inert o-ring, the Vino-Seal creates a hermetic seal that prevents oxidation and TCA contamination. A disadvantage with the Vino-Seal is the relatively high cost of each plug (70 cents each) and cost of manual bottling due to the lack of compatible bottling equipment outside of Europe. The design has won a Worldstar Award for Packing Excellence from the World Packaging Organization.                                                                                                                          

Vino-Lok Selection (the glass version) has been available in Australia since 2005 and is being used by some of Australia's leading winemakers to seal their iconic wines. Numerous contract bottlers around Australia are able to apply the seal to bottles with the Vino-Lok Finish. Automated machinery to apply the glass stopper and the modified aluminium short-cap are now available also.

Vino-Lok not only protects the wine from leakage and gas transfer, it is also easily resealed to the bottle, making it ideal for any wines which may not be consumed immediately upon opening. The small oxygen transfer rate allows the wine to mature in the bottle slowly, allowing the consumer to cellar the wine safely for many years, and still enjoy the wine as the winemaker intended it when it is finally opened.

Zork - Invented by Conor McKenna and developed by John Brooks in Adelaide, South Australia, Zork is an alternative wine closure that seals like a screw cap and pops like a cork. The Zork closure consists of an outer tear-tab which seals the closure to the wine bottle, an inner metal foil which provides an oxygen barrier similar to a screw cap, and an inner plunger which creates the ‘pop’ on extraction and reseals after use. The Zork has the convenience of screw cap and the pop of a cork and is recyclable.

Box Wine – Not really a closure but a “vessel” that’s gaining in popularity. From the standpoint of wine flavor and freshness, wine boxes have several advantages over traditional glass wine bottles. There is no possibility of a wine becoming “corked” and they keep air away from the wine, even after partial consumption. It also ships a lot easier and generally difficult to break or rupture. Interestingly, the patent for box wine was granted in 1965.

There is continuing opposition to the use of alternative closures in some parts of the winemaking industry. In March 2006, the Spanish government outlawed the use of alternative wine closures in 11 of Spain's wine producing regions as part of their (Denominacion de Origen) D.O. regulations. Italy has done something similar, and of course Portuguese wines will never see anything but cork in their wine bottles. The fact Portugal produces over 50% of the world’s wine corks may have something to do with that.

My opinion? Any closure that keeps wines fresh and flavorful and doesn’t add cost is ok by me. I don’t need to “pop a cork” to enjoy my wine.