Diam closures flawed?
An interesting study by German wine merchant, Rolf Cordes, reached a conclusion that Diam closures introduce atypical bitterness (ATB) into wine.
Cordes, a prolific wine taster, noticed that wines sealed with Diam closures all seemed to have a heightened bitterness. He set up a couple of informal trials and found that water, as well as wine, changed flavour after only two days contact with Diam closures.
A more formal and larger tasting with experienced and independent tasters compared the same wines with and without contact with Diam. Cordes reached the following conclusions:
- Because Diam closures are made using identical production techniques, they all introduce the same amount of ATB to wine making it difficult to detect because all wines under a single label will taste the same.
- High concentrations of tannin, acidity or residual sugar exacerbate the intensity of ATB.
- ATB appears to increase the longer the wine is in contact with the Diam closure and also under more oxidative conditions (e.g. allowing the wine to rest in a decanter).
- “Diam closures, regardless of their model, are not sensorially neutral”.
I occasionally hear winemakers and sommeliers complain about Diam corks but I have never seen a study supporting any claim of a flaw in the closure.
To read Cordes’ full report go to http://www.diam-test.info/Diam-ATB-english