Synthetic closures

Popularly known as ‘plastic corks’, these have appealed to producers on the basis of cost and reliability. They satisfy the wine drinker’s need to wrestle with a corkscrew while alleviating the risk of cork taint, but they have the disadvantage of not being biodegradable (although manufacturers are attempting to produce more sustainable versions). It has proven surprisingly difficult to find synthetic materials that replicate the natural properties of cork in order to provide a tight seal while remaining easy enough to extract from, and reinsert into, the neck of the bottle. The first brands to establish a market presence, most notably Supremecorq and Integra, were based on a one-piece injection-moulded design. These early examples were hard to extract and almost impossible to reinsert. They also allowed too much oxygen ingress (see oxygen transmission rates), making them suitable only for wines intended for early consumption. The better-performing synthetic closures now available are made by an extrusion process with a separate smooth plastic sleeve. After a period of consolidation in the market, Nomacorc is now the dominant manufacturer of synthetic corks, and has released a ‘Select’ series of closures offering different oxygen transmission levels to suit different wine styles. There are indications that these improved synthetic closures may also be suitable for wines intended for ageing. Another concern surrounds the capacity of synthetic closures to ‘scalp’ flavour by absorbing volatile components from the wine (see flavour scalping). Natural corks also do this but to a lesser extent. Synthetic closures are cheaper than all but the poorest quality natural corks and have the advantage that, unlike screwcaps, they do not require producers to adopt new bottles and bottling lines.