If you go into a supermarket in the UK, the majority of wine bottles will be sealed with screwcaps. In a supermarket in Spain or France there are very few.  Why is this?

Cork has been the traditional closure for wine bottles for hundreds of years. It works very well for the most part but has a couple of disadvantages. First, the cork can deteriorate in the bottle –  sometimes disintegrating into dust and sometimes becoming porous , allowing the wine to oxadise.  Keeping the cork damp is the main way to reduce the chance of the cork deteriorating.  This is why wine is traditionally laid down in cellars to keep the cork moist. Second, cork can contain microbes which, when presented with chlorophenol compounds, can produce a chemical called trichloroanisole (TCA) which permeates into the wine and causes the distinctive smell of a mouldy paper that is known as cork taint.  Such wines are said to be “corked”.  As well as the unpleasant smell, the wine becomes unpalatable. The chlorophenols can come from certain pesticides used in cork forests, the presence of treated wooden pallets, and the use of chlorine as a cleaning product in wineries.

Alternative closures have been developed to remove these risks.  They are mainly synthetic corks and screwcaps.  They both have the advantage of not requiring the  bottles to be laid down horizontally.  Synthetic corks are a simple replacement but have been thought to impact a plastic flavour on the wine.  They are only guaranteed for 2 years and can leak beyond that time. They tend therefore to be used for cheaper wines for earlier drinking.

Screwcaps have a much longer lifespan and do not appear to taint the wine, so they have been used for both low and   high quality wines.

One of the major decisions a winery must make about closures is perception in the market.  Screwcaps were historically used on very cheap wines both in continental Europe and America. So there is a prejudice against screwcapped bottles which deters producers from putting their better, more expensive wines in them.

In the Southern Hemisphere and Brita this prejudice has almost disappeared, although some traditionalists still prefer cork. In upmarket restaurants, the ritual of opening a wine with a corkscrew is still seen as part of the experience and people have objected to paying a high mark-up on screwcapped wines.