"Thanks to an exclusive patented process for 'de-aromatising' cork, the 'Diam' and 'Mytik Diam' corks are the only cork closures that are completely neutral in sensory terms," the manufacturer promises, guaranteeing "the preservation of the wine's aromas throughout its storage period" as well as "consistently impeccable enjoyment". For this, the cork granulate is treated with the "Diamant®process" technology. According to the company, it uses "the possibilities of supercritical CO2", with which "the volatile and harmful substances are to be extracted, thus eliminating the risks of
TCA 'cork taint'". Renowned companies such as
Champagne producers
Mumm and Billecart Salmon,
Louis Jadot from Burgundy,
Hugel et Fils in Alsace and the renowned
French wine consultant
Michel Rolland use and promote
Diam corks. However, wine merchant Rolf Cordes from Mühldorf in Bavaria has doubts about the company's promise. He claims that
Diam corks produce an "atypical
bitter tone". He has found this out after many years of tasting wines from all over Europe. To prove his thesis, he recently organised his own sensory investigation and now wants to publish the results online.
Wein-Plus asked him about his accusations, findings and evidence.
Wein-Plus:
Mr Cordes, you say that the agglomerated corks of the
French supplier
Diam Bouchage, which are used billions of times worldwide, could negatively change the taste of the wines sealed with them. What makes you think that?
Rolf Cordes:
When tasting red,
rosé and white wines from different regions and grape varieties, I discovered taste parallels of a negative nature. I set out to find the cause. The only thing that all the wines had in common was the closure - the
Diam cork.
Wein-Plus:
According to your observations, could corks from similar production processes of other manufacturers also be affected?
Rolf Cordes:
Basically, the conventional agglomerated corks are not considered sensory neutral. I notice this again and again, regardless of the manufacturer. However, the sensory changes of those corks are different and not as uniform as with the
Diam corks.
Wein-Plus:
In your opinion, what defect do these corks cause? How can it be described?
Rolf Cordes:
I call the defect an "atypical
bitter tone", UTB for short. It causes an extraordinary dryness primarily in the pharynx, uvula and oesophagus. This astringency lasts longer than with the usual tannins, which are primarily felt in the mouth and palate. Under increasing influence of the air, a clear disharmony becomes noticeable.
Wein-Plus:
When did the fault
first consciously occur for you? With which wines?
Rolf Cordes:
It's impossible to say. It's like a jigsaw puzzle. When the picture is finished, you no longer know which piece you started with.
Wein-Plus:
Are you sure that only
Diam corks are affected?
Rolf Cordes:
Up to now, I have not noticed this missing tone in this way in any other agglomerated corks. The uniqueness was also confirmed to me by the experienced oenologist Volker Schneider from Bingen. He ran an independent wine
analysis laboratory for many years.
Wein-Plus:
Sensory
analysis is subjective. Can you prove the contamination by the cork?
Rolf Cordes:
Yes. I selected eight different wines. For each wine, half of its quantity was brought into contact with a
Diam cork. I used two different procedures: On the one hand, three wines were bottled, two bottles per variety were screw-capped and sealed with Diam. In addition, we filled five wines, which were screw-capped, into brand-new 1.5l glass containers. For each wine, there was one glass container without a cork and one that contained two
diam corks. The wines in the glass containers were gassed with argon to prevent oxidation. The three bottled wines in group 1 remained in contact with the
diam corks for 37 to 94 days. The five wines in group 2 had a contact time of 32 to 72 hours, a maximum of three days. The wines were then bottled in coded 100ml bottles and sent to the tasters.
Wein-Plus:
Who were the tasters?
Rolf Cordes:
They were wine journalist Jens
Priewe, oenologist Volker Schneider, master winemaker and
DLG tester Lukas
Schmidt, winemaker and LWK tester Daniel Theisen, plus experts from wine control, quality wine testing and analytics as well as winemakers, wine merchants and end consumers.
Wein-Plus:
What was the result?
Rolf Cordes:
The
test proves that
Diam corks are not sensorially neutral. Due to the identical manufacturing process, it is irrelevant which
Diam type is used.
 |
| Copyright: Rolf Cordes |
Wein-Plus:
How high was the recognition rate of the testers involved?
Rolf Cordes:
The off-flavour was recognised between 81 and 100 per
cent in seven wines and 72 per
cent in one wine.
Wein-Plus:
Why did you decide on this
test procedure? Did you develop it on your own?
Rolf Cordes:
A sensory
test corresponded exactly to my requirements. The aim was to prove the effect on the wine and not to find the causative substance. I was advised in setting up the
test by Volker Schneider, an oenologist with a great deal of experience in research, sensory
analysis and analytics.
Wein-Plus:
Some oenologists, however, say that the experimental set-up would probably change every wine with an off-flavour - no matter which closure you use. What is your opinion on this?
Rolf Cordes:
There were three wines which were
corked with
Diam and five wines which came into contact with a
Diam cork in a glass container. The second method is generally used in research to control the transfer of substances into a solution, for example in the
TCA testing of natural corks. The assertion that any closure is likely to alter a wine with an off-flavour is expressed very sweepingly and is not tenable as such. However, if any other closure were to cause an off-flavour under these conditions, I believe it would have to be tested just as rigorously and carefully as
Diam was in this case.
Wein-Plus:
The
Diam cork promises the complete exclusion of
TCA, i.e. corkton. That is why it has been used worldwide for many years. Why has the fault you observed not been noticed by any winemaker, merchant or oenologist so far?
Rolf Cordes:
The basic prerequisite for coming across this off-flavour is to recognise it in the
first place. Perhaps they have already noticed something out of the ordinary, but could not attribute it to the closure. If you search for
TCA, you will not find the UTB. When testing, it is necessary to swallow some wine, otherwise the essential areas in the mouth will not be wetted. Since there is often no comparison with uncontaminated wine, the influence of
Diam remains undetected. In general, these sensations are often attributed to acidity, tannins, grape variety,
climate, soil and stage of development. The developing disharmony requires continuous observation, which is not possible during quality controls and wine events due to time constraints.
Wein-Plus:
What do you want to achieve with your results?
Rolf Cordes:
The risk for
winegrowers and traders should be reduced. Faulty and disharmonious wines are not conducive to business, quite the opposite. The wine drinkers, i.e. the customers, have a right to wines that are not affected by closures. I am of the opinion that the producer
Diam Bouchage must urgently tackle the identification and elimination of the causative substance.
Wein-Plus:
Have you contacted
Diam about this?
Rolf Cordes:
No.
Wein-Plus:
What are your next steps?
Rolf Cordes:
Now it is a question of making these results available to as many
winegrowers, oenologists and traders as possible. For this purpose, I have had them translated into five languages. Every trader, wine drinker can download the tests as a PDF at
www.diam-test.info and forward them to his vintners at home and abroad. Of course, I will continue to observe the development in the field of closures.
