More Questions than Answers: the cork vs screwcap divide

While there are those who take up intractable positions on either side of the cork vs. screwcap divide, the truth concerning what the best closure for wine is lies somewhere in between. Grape.co.za editor Tim James CWM provides an overview.Years ago already most of us were convinced by one argument or another in the great cork versus screwcap debate. Or we were content with our prejudices or bored enough to ignore the whole business.

 

UK Master of Wine Jancis Robinson’s umpteenth article on the subject suggested that “everyone and his dog has a view on this by now” – that was in 2001. Now my two dogs take opposing stances (or don’t deny this), while I am less sure: not usceptical about the ultimate virtues of cork, but undazzled by a triumphal march of screwcaps in a scattering of tainted corkdust.

If this lack of conviction is more than just the mellowing of age, it’s partly because it is now apparent that the easy answers have been to inadequate questions. It is not as simple as acknowledging that cork has been damaging some five percent of the wine it has been sealing, and that therefore we should use screwcaps (or plastic or glass) – unless we are prepared to pay the price for a sentimental committment to “the romance” of cork. The debate is not merely about TCA taint any more, and there are new acronyms to deploy (start with OTR for “oxygen transmission rate”).

Absurdly, perhaps, everyone a decade back was loudly opining on the best way to seal wine, while the chemistry and microbiology of wine ageing – what was actually going on in the somehow-closed bottle – was imperfectly understood. Above all, we have since learned to ask: should there be some tiny transmission of air though the closure for a wine to develop, something that cork arguably allows, while metal-lined screwcaps do not? (Probably, though not necessarily always…)

That question is irrelevant, of course, for most wines, which either aren’t designed to mature in bottle, or aren’t given the chance to do so by impatient drinkers. Further, while the question is being asked and answered on behalf of more ambitious wines and their buyers, and while the closure industries are innovating, other forces that influence the debate are at work – notably the will of the producer to change the bottling habits of a few centuries, and the will of consumers to change their bottle-opening habits.

Screwcaps have made great headway, and claimed so much attention, that it would be easy to assume (as some do) that before long their trivial tinkle will be manifoldly multiplied, drowning out the mild pop! beloved of corkscrew-wielding traditionalists. Yet the largest cork producer, Amorim, has just had its most successful year ever, in both volume and turnover. Admittedly not all of the 600-odd cork producers did as well; there has certainly been a modest overall decline in cork usage in recent years.

Most of the world remains remarkably loyal to cork. Joaquim Sa, Amorim’s local General Manager, estimates the global closure market at 14 billion corks annually, with synthetic closures at below two billion and screwcaps coming in at a mere (but fast-growing) 1.5 billion.
It took a shamefully long time for cork producers to admit to the scale of the problem of tainted wines and to themselves as a significant source. We must thank the aggressively screwcapping brigade for prompting better quality control, and for the substantial research being undertaken by the major cork producers. The big guys in that industry tend, by the way, to blame sloppy little guys for much of cork’s bad image, and for the fact that the proportion of “corked” wines has not yet necessarily dropped greatly, despite their improvements.

The first focus of research is, of course, to find processes to effectively remove taint-causing TCA from cork without damaging the host’s splendidly useful structural properties.

Secondly, the scientists are developing socalled “technical corks” – often made (putting it simply) from reconstituted, treated fragments with an admixture of synthetic material: Diam is now perhaps the best known of these. Technical corks look fairly “natural”, and tests are suggesting that some might be taint-free as well as being suitable for long-term ageing of wines – and possibly acceptable to conservative wine lovers. It would not be absurd to wonder if these complex agglomerates might embody the future of the wine-cork industry – especially if they can help mitigate the lack of uniformity that inevitably characterises a natural product.

The category of synthetic closures is easier to dismiss – it’s surely not only me that finds them mostly squalidly ugly, hard to remove and harder to replace in the bottle. And if you’re going to move from cork, why to a secondrate imitation? Yet they are usefully cheap and, especially for lower-end wines, seem to have their place, especially in the USA. Studies generally show them to be comparatively poor seals, however, allowing too much oxidation too quickly, suitable only for the quick-drinkers.

There are minor but interesting and valid alternatives to the big players – the Vino-Lok glass stopper, the Zork, the Guala Seal, and the good old crown cap amongst them – but the headline news in the closure business, especially in the southern hemisphere, remains screwcaps. Two of the most successful New World producing countries, New Zealand and Australia, are increasingly committed: the former more than 90 percent so, the latter well over half. Conversion is much, much lower in South Africa, but the market is growing, especially for whites and rosés. Of the big consuming countries, it is the UK that is the most important for screwcaps: supermarkets are keen, and the acceptability of metal tops amongst consumers is increasingly rapidly, even for higher-priced wines.

So is it only consumer conservatism delaying the dawn of the Age of the Screwcap? Not quite. Although doubts are scorned by True Believers, there is a serious debate around the question of reduction in wines sealed with impermeable closures. Reductive aromas relate to the impact of sulphur compounds – and it’s a complicated question, which many deny the significance of for screwcaps: the problem can easily be sorted out in winemaking, some assert. Let’s leave it there for now, noting only the concern.

The other technical (as opposed to marketing) doubt about screwcaps is their suitability for ageing serious red wine: tests and experience have mostly been with white wines. But screwcaps are not necessarily impermeable to air – different linings can allow for the same minuscule amount of oxygen transmission as many corks do. This is not a finally accomplished technology: research and progress continue with the screwcap as with other closures.

At present no means of closing a wine bottle is demonstrably perfect – few of even the most fervent partisans, in their honest moments, would deny that.

Environmental concerns are also ever-more important and will play a role (a chance for cork producers to feel comparatively smug, surely). Understanding of the microbiology and chemistry of wine is improving, and so are a number of technologies.

Perhaps, one day, a single closure type will prove perfect for all wines, but this seems unlikely. An important lesson learnt in the past decade’s investigations is that the same wine sealed with a dozen different closures is immediately, irrevocably destined to develop in a dozen directions. Different wines will call for different ways of closing them. That’s surely all we now know for certain. In conjunction with what we’re learning about glass and aluminium and cork – and about wine – that’s a great start.