Close Call

So if cork sales are growing, and screwcap sales are growing, and the overall wine market is static, who is losing out? It has to be synthetic corks. “It’s now increasingly a two-way race instead of a three-way,” says De Jesus. “There’s a solid entrenching of positions, with a stable market share for corks and screwcaps ahead of synthetics.”

Yet the leading synthetic closure manufacturer, Nomacorc, reports sales of 2 billion annually, and that these numbers are growing. It must therefore be poor-quality synthetic closures that are taking the hit. This brings us on to the topic of innovation, something that all closure companies are busy doing in a bid to gain or protect market share.

Nomacorc has been one of the most innovative of all closure manufacturers. A while back it initiated a multinational research project on the interaction of oxygen with wine, in collaboration with major wine science institutions in a number of countries. This research was intended to provide a theoretical background for its current range of closures, the Select Series, which offers a range of different oxygen transmission levels.

Oxygen transmission

Oxygen transmission (known as OTR) is an important but rather geekily technical concept for wine bottle closures, and it needs a little unpacking.

In basic terms, a closure has to keep wine in the bottle, and keep air (along with it, the reactive gas oxygen) out. But if the closure keeps out all the oxygen – that is, it is a hermetic seal – then this can cause problems.

What happens is that the lack of oxygen can result in some unwanted chemistry taking place with regard to a group of smelly chemicals called volatile sulfur compounds, including the likes of sulfides, disulfides and mercaptans (aka thiols). But, while a little oxygen is helpful, too much causes oxidation. And the precise amount of oxygen that enters the bottle will affect how that wine develops after bottling. To make this all a little more complex, different wines respond differently to post-bottling oxygen exposure.

Nomacorc has a software tool called the NomaSelector which allows winemakers to match the right Nomacorc closure to their wine by answering a series of questions. The increased knowledge of the role of oxygen in the development of different wine styles provided by the research project allows winemakers to use closure oxygen transmission level as an extra step in winemaking. And they have demonstrated the difference that varying levels of closure oxygen transmission can have on a wine in a series of comparative tastings of the same sealed with different closures.

Other companies are also offering closures with specific oxygen transmission (OTR) levels. For example, Diam offers its range in three different transmission levels, medium, low and very low.

For a long time, there were only two screwcap liners for wine – Saranex (low OTR) and Tin/Saran (extremely low OTR). But this year Amcor, the second largest screwcap manufacturer, announced the release of five liners designed to offer a range of OTRs to winemakers.

California giant winery Gallo’s technical arm is also at the development stage with a series of new liners which it is likely to release in 2014. While many winemakers are perfectly happy with the existing liners (for example, New Zealand wine is 95% screwcap-sealed, using almost exclusively the very low OTR Tin/Saran liner), the existence of screwcap liners with different OTRs will be an attractive prospect for those who like the convenience of screwcaps but who in the past were worried by the extremely low OTRs of the Tin/Saran liner, which carries with it attendant risks of unwanted ‘reductive’ characters developing after bottling.