Michael Nash is an Australian from an IT background with a deep interest in Cape wines. He had planned to direct a luxury wine tourism programme to South Africa before the incompetence of our tourism authorities – rather than Covid-19 – put paid to the idea. This doesn’t mean that he’s given up drinking the top wines from many of our best known producers. On the contrary, though he is permitted to buy wine where he has been locked down (you could argue that, unlike South Africa, Australia’s collective leadership is at least smarter than its Prime Minister) he has chosen to plunder his Cape wine collection.
Increasingly he has found that several wines – all perfectly stored – have not aged well. He not alone in this: WineMag’s Christian Eedes, reviewing the 2010 vintage reds ten years on, observed that some of the wines were “unduly advanced and in some cases, oxidised.” Nash has been tasting his Cape wine in Australia, while Eedes was judging them less than 50 kms from where they were produced. Clearly the sea voyage to the east coast of Australia cannot be the sole reason for their evident deterioration.
There may be various technical reasons for the failure of some of these wines to have matured satisfactorily. One possibility is that they were bottled with high levels of dissolved oxygen. The other – and it’s the one favoured by Michael Nash – is South Africa’s obsession with cork closures. He is certainly correct that Stelvin/screwcap’s hermetic seal helps to eliminate the risk of oxidation.
Cork, unlike Stelvin, admits a certain amount of air: the problem is that it’s impossible to know exactly how much air each individual cork lets into the bottle. Some seal a bottle almost as perfectly as a screwcap; others let in so much air that within a few years the wine is tired and old.
Random bottle oxidation is a bigger problem for producers who refuse to use screwcap closures than the once widespread issue of cork taint (TCA). Wineries willing to spend upwards of R20 per cork can acquire the ultra-premium selections which are guaranteed TCA-free, but even that investment does not bring certainty about the porosity of the cork.
For a lot less money they could buy top-of-the-range cork agglomerates (such as Diam) and obtain a pretty much taint-free closure which looks like a standard cork and also does not admit any air. It’s pure snobbery to insist on a long, solid cork whose cost is much the same as the combined price in all the other dry goods – bottle, capsule, label and box.
It should be clear from all this that closures, at least in the South African trade, are more about marketing than functionality. Australia and New Zealand have long ago embraced screwcap technology. Led by the riesling producers – the delicate aromas of whose wines revealed how extensive a problem cork taint was twenty years ago – the Antipodean industries shifted from cork to Stelvin in a matter of a couple of years. By way of an example, the 2015 Henschke’s Hill of Grace (which would sell for over R14000 a bottle in South Africa) is now screwcap closed.
Closures have become much more sophisticated since 17th century wine merchants took to using the bark of the cork oak to seal wine bottles. Screwcap liners can now allow for limited but precise oxygen permeability, mimicking the benefit of real cork but delivering added certainty. It seems a no-brainer for 21st century producers to embrace Stelvin.
Except it’s not: some of the early acceptors (including a few in Australia) have quietly gone back to using cork, citing reasons other than marketing issues. Contrary to Michael Nash’s experience and the Australian wine industry’s own research, they claim they prefer the way wines evolve under cork. It seems the best science in the world cannot cannot change what it is about wine that appeals to oenophiles: the emotional connection of authenticity and craft.