Corks, screw caps or plastic stoppers – what is the best way to seal a wine bottle?

Quality and influence on the wine: Natural corks, made from the bark of the cork oak, are the traditional closure for wine bottles. They are considered a symbol of high-quality wine and are particularly appreciated for wines with storage potential. The cork allows a minimal oxygen supply, which can positively influence the maturing process. However, there is a risk of a so-called cork taint (caused by the substance trichloroanisole, or TCA), which can make the wine undrinkable.

Sustainability and costs When the cork bark is harvested, the trees are not felled but stripped, which does not harm the tree. Corks are biodegradable and come from sustainably managed forests, particularly in Portugal and Spain. The cultivation of cork oaks contributes to biodiversity and binds CO2. However, they are more expensive than many alternatives and the availability of high-quality cork can fluctuate. After all, a period of ten years should elapse between each harvest to allow the bark to regenerate.

Quality and influence on wine Screw caps, usually made of aluminium, have been gaining in popularity for years, especially for young and fresh wines. They provide a hermetic seal that almost completely prevents oxidation and preserves the wine's original freshness. However, they are less used for wines with a long ageing potential, as they do not allow any oxygenation.

Sustainability and costs: Producing aluminium is energy intensive, but the material is recyclable. Screw caps are generally cheaper than natural corks and, thanks to their reliability, minimise the risk of wine loss due to cork damage.

Quality and influence on the wine Glass corks are eye-catching and combine elegance with functionality. They provide a tight seal, are neutral in taste and odour, and prevent extraneous aromas from affecting the wine. In addition, glass corks are suitable for all types of wine, from young to aged.

Sustainability and costs: Glass corks are reusable and recyclable, but energy-intensive to produce. They are also more expensive than many other types of closure, making them more of a niche solution.

Quality and influence on wine Plastic corks offer a cost-effective alternative to natural corks and avoid the risk of cork taint. However, they often do not seal perfectly and can lead to undesirable results in wines with a long storage life.

Sustainability and costs Plastic corks made from petroleum score poorly in terms of environmental friendliness because they are difficult to recycle. On the other hand, they are a cost-effective alternative to cork stoppers.

Research into innovative closure solutions is on the increase. Bio-based plastics and recyclable materials are gaining in importance – for example, stoppers made from sugar cane are now available. Hybrid closures that combine cork and other materials are also being tested.

Natural corks remain the first choice for high-quality and storable wines. However, screw caps have gained a significant market share, particularly for young, inexpensive wines and white wines. According to Jürg Gafner from the Agroscope research institute, around 60 per cent of all Swiss wine bottles now have a screw cap.