The study of DIAM closures and ‘atypical bitterness’ (ATB) by German wine professional Rolf Cords has come to light recently. He highlights the ‘flaw’ of ATB that he and his team have detected and identified in a study conducted over July to September last year. You can see the report at: www.diam-test.info/Diam-ATB-english
A winemaker recently sent the study to me for comment. The subject of closures is a very important and complex one which can be very emotive, especially when livelihoods are at stake. Following is my reply, which I’ve kept brief, so as to retain an overall and hopefully practical perspective:
I certainly see ‘pros and cons’ with Diam closures, and don’t regard them as them as the best solution to the issue of bottle closures.
There has been evidence over the years where a number of tasters/judges consistently pick up a ‘Diam character’ in the wines sealed with it. I personally don’t pick it up, so clearly there are personal thresholds involved in its perception.
Knowing how Diam corks are made, it is inevitable that extraneous characters will emerge.
I’ve participated in a number of trials of wines with ‘Natural cork vs Diam vs screwcap’ and while there is some variability in the results, I get certain feelings about each closure:
- The variability of natural cork and predisposition to show TCA is its major problem. But the best bottles under cork are brilliant – the cork adding its natural flavour/texture/whatever you like to call it.
- Screwcap is super-consistent, and retains freshness. But austerity is the issue. Reduction retention and technical failure leading to oxidation are problems.
- Diam to me is also very consistent, but a dullness can be apparent.
The consistency of screwcap and Diam is clearly one of the key factors for their usage. I tend to favour these too, especially from a commercial perspective. But natural cork can perform extremely well, so I don’t write it off, though experiencing a corked wine is a real shame.
So I take a step back from the closure issue, with the awareness of the ‘pros and cons’. The industry players are continually striving to improve their products, so what develops and how the market reacts to the changes will be very interesting to follow.