A special and increasingly popular type of closure (English screw cap, twist or ROPP = Roll On Pilfer Proof Closure) of wine bottles as an alternative to cork (Natural cork) from the oak bark. These are made of corrosion-free metal (mostly aluminum alloy) with an internal sealing layer polyethylene (PE), PVDC (Polyvinylidene chloride) or tin foil. In the beverage industry, this is also known as MCA (metal closure aluminum). The emotionally led discussion as to whether this is associated with a “loss of culture” is offset by the relatively inexpensive manufacture and the fact that this creates the problem of Korkschmeckers can be avoided with natural cork. In addition, the often used pro argument for the "plop" is with Weingenuss not sensible as a sensual pleasure, because a bottle should be opened as silently as possible (this applies particularly to sparkling wine).
On airplanes, for example, wine bottles with a screw cap have only been available for decades. Nobody will find anything here, because the advantage of easy and unproblematic opening in a narrow plane is obvious. Another advantage is that opened bottles can be resealed very easily. Visually, attempts were also made successfully to take account of the rejection of the cork friends towards alternative closures. Externally, such twist locks are no longer recognizable as such. The first application for wine bottles took place in the late 1970s Australia, The producers in Clare Valley (South Australia) are considered pioneers. Many producers soon followed New Zealand and California before the boom started in Europe.
In contrast to a cork with a screw cap is the whitespace much larger in the bottle neck. The volume is 15 milliliters, which means a relatively high oxygen content of 4.2 milligrams. Especially with a cold one bottling Air (and therefore oxygen) remains in the empty space. For this reason, air displacement is required when filling inert gas or closing under vacuum is advisable. An often voiced argument against screw caps is that due to the much better seal than natural cork, oxygen supply is only possible to a small extent (factor three to four), but this is for the bottle aging is absolutely necessary. But this is more of an argument for the screw cap. Because the oxygen that may be in the bottle in the bottle neck (but often today) inert gas or vacuum) or in dissolved form in the wine itself is sufficient.
This was impressively underlined at a Riesling tasting in Sydney Australia in 2003. A Riesling was presented to a group of leading producers from all over the world. The age was estimated between six and ten years, but in fact it was a 1982 Riesling, which was then closed with a screw cap. At least in this case, this indicates that the maturation with such closures is slower, but the almost perfect sealing due to the twist lock does not result in any loss of quality. Whether this is generally applicable cannot, of course, be deduced from a single example. But there are numerous other examples that even with an absolutely tight seal, the maturation of the wine in the bottle is not adversely affected in any way. This fact was also confirmed, for example, by several test series in the German research institute Geisenheim (Rheingau) fully confirmed.
Latest research (such as on AWRI Australia) have in any case shown that the smallest amount of oxygen entering through the occlusion during the bottle aging very conducive to the development of the wine flavorings and colour can be. In Australia, the screw cap is very positive. In early 2002, the Australian multi South Corp announced that all Rieslings (including Penfolds. Rosemount Estate and Wynns ) of the 2002 vintage can be filled with a screw cap instead of natural cork. From the 2004/2005 vintage, all Penfolds white wines will be sealed with it. This producer has also been very successfully testing top-quality red wines since 1995. No problems were found, the wine matures completely evenly. In 2004 this was the first cru classé winery from Bordeaux Château Couhins-Lurton (Graves), which closes its white wine, which is one of the best in Graves, with a new screwdriver version.
More and more wine producers are switching to this technology. Especially in New Zealand with 90% and in Australia with 60%, the proportion of alternative closures is extremely high, with by far the highest proportion of twist locks. There was significant growth in Germany (one third each with a screw cap, plastic and natural cork), France, Austria, Italy and Spain with around two thirds of the wine with screw cap, as well as Argentina and Chile. A very well known brand is STELVIN which has almost become a synonym for this type of closure. The Company VinPerfect offers a screw cap that contains microscopic holes in its cap through which air can pass. This supply in the smallest amount is called nanooxygenation (see under micro-oxygenation ). See also under closures,