Screw cap (wine)

A screw cap is a metal cap that screws onto threads on the neck of a bottle, generally with a metal skirt down the neck to resemble the traditional wine capsule ("foil"). A layer of plastic (often PVDC), cork, rubber, or other soft material is used as wad to make a seal with the mouth of the bottle. Its use as an alternative wine closure is gaining increasing support as an alternative to cork for sealing wine bottles. In markets such as Australia and New Zealand screw caps on bottles have overtaken cork to become the most common means of sealing bottles, right across the wine industry.

Compared to cork, screw caps reduce the wine faults of oxidation and of cork taint, although it is possible to find TCA contamination in a screw cap bottle. Screw caps are generally perceived as easier to open. Screw caps have a much lower failure rate than cork, and in theory will allow a wine to reach the customer in perfect condition, with a minimum of bottle variation. However, cork has a centuries-old tradition behind it, and there are also concerns about the impact of screw caps on the aging of those few wines that require decades to be at their best. Some argue that the slow ingress of oxygen plays a vital role in aging a wine, while others argue that this amount is almost zero in a sound cork and that any admitted oxygen is harmful.

Producers in Champagne have aged their wines under crown cap for quite some time, however, the crown cap is replaced by the traditional cork at the end of the second fermentation.

The converse of oxidation is reduction, and it has been suggested that screwcapped wine leads to reductive characteristics. These include a sulfur smell which in some circumstances adds a pleasant pungency to the wine, or may be distasteful.

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Wikipedia