Seeking closure once and for all? Cork versus screwcap versus Diam
Sarah Marsh MW reports from a revealing and surprising comparative tasting of wines aged under different types of closure
London for a tasting of cork versus screw cap, largely from Guffens-Heynen, in a vertical that stretched back to 2003. You might suppose this face-off would be a forgone conclusion, particularly for wines many years in bottle, but on the contrary, the exercise was full of surprises.
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The first small surprise was the presence of Diam. Before the tasting I had time for a quick chat with Julien Desplans, Jean-Marie Guffens’s right- hand man and winemaker since 2006, who explained: “With hotter and hotter vintages, we decided to change many things, from using cement tanks, to a very long natural fermentation, so we needed to be as reductive as possible and we felt there was more certainty to continue the reductive aging with screwcap.” So, in 2003, disillusioned by the unreliability of cork, Guffens began bottling part of his production under screwcap for Farr Vintners, while continuing with cork. Come the 2010 vintage, he abandoned cork for Diam at the domaine, and in 2012 he did the same for the négociant wines under the Verget label.
While this tasting focused largely
on Guffens-Heynen and Verget, it also included a few wines from the Brajkovich family at Kumeu River, who were pioneers of screwcap in New Zealand from the 2001 vintage. Farr Vintners have long collaborated with Kumeu River, importing these screwcap wines into the UK—which was a courageous move 20 years ago. There was also wine from Felton Road Winery in Bannockburn, which started using screwcap in 2004, and from Château Rauzan-Ségla in Margaux, which made a parallel experiment with its 2009 and 2010 Ségla. Finally,
sunny winter’s day found me striding alongside the River Thames to Farr Vintners in
David Gleave MW, a staunch advocate of screwcap, put Italy in the ring with Isole e Olena: 2005 and 2016 Cepparello, courtesy of Liberty Wines. For each wine there was a screwcap version and another under cork or Diam, which were assessed by 17 experienced tasters (listed at the end). We were told the wine but not the closure, and votes were taken after each flight of six wines. The panel’s scores are included in my tasting notes. My observations are based on some instant impressions during the very swift tasting time we were allotted, but more so from reflection after the tasting as I reviewed my notes and considered all the facts.
As many readers will be aware, a cohort of top producers of white Burgundy have made the switch to Diam over the past decade, but very few use screwcap, and for those who do, it is for entry-level wines. Stephen Browett remarked, “Jean-Marie Guffens is to be applauded for his decision to experiment with closures 21 years ago, when most producers still had their heads in the sand, refusing to acknowledge the clear problems of white Burgundy at the time.” But as he also pointed out, Guffens is not Burgundian, so was more open-minded. Certainly, being Belgian he would not be so entrenched in tradition. Once we had got stuck into the
tasting, it gradually became clear that all is not equal among screwcaps. Julien Desplans had told me that Guffens began by using the Sarantex screwcap, but switched to SaranTin in 2014. As the wines were not shown in chronological order, it was really afterwards, contemplating my tasting notes, that the extent of the effect of the two screwcaps became apparent. Of the six wines tasted under Sarantex screwcap, I preferred the alternative closure for all but one set, for which
I had no preference. I was aware that screwcaps permitted different levels of oxygen ingress but as I don’t assess many wines under screwcap, I have not thought much about it, so I genned up on the difference with the Australian Wine Research Institute after the tasting. It is not the aluminum screwcap that provides the protective barrier, but a polyvinylidene chloride (PVDC) insert that was developed in Australia in the 1970s and is commonly referred to as Saran. The “liner” market is currently dominated by two inserts that contain Saran—Saranex and SaranTin. In the latter, the Saran is layered with a fine tin layer developed to reduce the oxygen transmission rate. SaranTin is better equipped for long-term aging and guaranteed for 20 years, twice that of Saranex. There is a rather fancier version of screwcap, with variable oxygen transfer rate (OTR), allowing controlled oxygen ingress. The AWRI website states, “SaranTin liners play a large role in the Australian and New Zealand wine market for wines sealed under screwcap. In the European wine industry, however, producers using screwcaps tend towards Saranex due to the perception that wines sealed with SaranTin can develop ‘reductive’ characters due to the very low levels of oxygen ingress through the liner.” Hold this thought for later. Meanwhile, it’s worth remarking that the earlier (pre-2014) vintages of Guffens wine bottled under Sarantex screwcap are older than the guaranteed ten years for this closure. Based on my impressions, I would drink them now, and, for that matter, would hesitate to age any wine under Saranex closure for too long. This reminds me that somewhere in my cellar I have a case of premier cru Chablis from Louis Michel under screwcap when they experimented with a dual bottling,
THE WORLD OF FINE WINE | ISSUE 87 | 2025 | 29
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