Diam hits back over ‘bitterness’ claim

5th February, 2016 by Rupert Millar

A German négociant has claimed that wines closed with Diam corks develop a strong bitter flavour – an accusation the manufacturer strongly rebuts.

diam corkThe claim by Rolf Cordes surfaced at the end of January on the German wine review Wein Plus. One of Diam’s directors met with Cordes and swiftly concluded he was a “fantasist”.

Cordes claimed he found that wines under Diam closures developed a “persistent dry aftertaste” that he christened “atypical bitterness”. He explained he had taken eight wines, a mixture of red, white and rosé and from different regions and grape varieties, and poured 1.5 litres of each into two jars to create a pair of each.

Into one of the jars of each pair he added two Diam corks and left them to macerate for between two to 94 days. In the end, he claimed that in a tasting with 10 others seven of the eight wines left with the Diam corks had developed this “atypical bitterness”. Proof, he added, that Diam was not a neutral closure.

According to French site Vitisphere, one of Diam’s oenologues and directors, Alain Schmitt, once he heard of the ‘findings’, went to meet Cordes and came away less than impressed.

He told Vitisphere: “Mr Cordes is an fantasist who wants to cause a stir. He works in a museum and opens his garage two times a week to sell some bottles of wine. It was in this same garage that he conducted his pseudo-study.

“He didn’t bother to compare Diam to other corks and came up with no other analysis (SO2 or O2 levels)”.

He continued that Cordes had confused reduction and bitterness and that wines with low pH levels and high levels of sulfites could appear “hard” and closed several months after bottling, becoming more expressive over time.

He added that as a supplier to nearly 50% of white Burgundy’s grand cru producers, many leading Champagne makers and several other well-known wine producers across France, “if our corks made the wines bitter we would now about it.”

He concluded that if the rumours were judged to have any impact on Diam’s sales then the company would “not let the matter stand”.

A letter has been sent to all of its distributors and Wein Plus on the matter.

“If necessary we will defend our brand in front of a tribunal,” added Schmitt.

12 Responses to “Diam hits back over ‘bitterness’ claim”

  1. Bruce Hampton says:

    I have also found the typical bitterness in some tastings with this closure.

  2. Knuth says:

    I have often found the bitter also with other aglomerati corks, I am often found also a musty smell, sulfur or stale.
    I do not feel a strong effect but more or less almost always

  3. Curt Brown says:

    Clearly a flawed test, with no control. Other corks should have been compared. I’m not so sure that any wine with a couple of corks floating in it would taste ok.

  4. Wes Hagen says:

    After 10+ vintages under DIAM, i would use no other closure. I find 100% consistency from bottle to bottle, and unlike the guy who did the test, i have been a professional wine judge for 20+ years.

  5. Matt Thomson says:

    The control would be the experiment with the same conditions except without corks of any kind. There’s no necessity to test other corks.

  6. Rolf Cordes says:

    I`m the fantasist, Rolf Cordes.
    Yes, I have a small shop and I`m working in a museum.
    But since 23 years I`m in the winebusiness.
    Please have al look here: http://www.diam-test.info/Diam-ATB-english
    Is this the work of a fantasist?
    Best wishes
    Rolf Cordes
    PS. Some very important persons starts in a garage 😉

  7. Michael Jenkins says:

    In order for the “experiment” to be perceived as valid, a better process would need to be followed. One would have to question the motivation of an experimenter who set out to “prove” one specific brand of closure would effect the taste of the wine. Why wasn’t the experiment carried out in a controlled environment?
    Why weren’t corks from other manufacturers included?
    Why were the corks left to float in the wine when that is not a natural part of wine production or consumption?
    Why were the corks floating in opened wine for 32 hours – also not natural in the production or consumption of wine?
    Why were the Diam samples all labeled A-H “2” rather than a random mix of numeric assignments (this may tend to introduce prejudice into the sampling).

    While Mr Cordes may (or may not) be correct in his summary statements, the experiment is so flawed that it can not be taken seriously as any high school science student will tell you.

    • Rolf Cordes says:

      In order for the “experiment” to be perceived as valid, a better process would need to be followed. One would have to question the motivation of an experimenter who set out to “prove” one specific brand of closure would effect the taste of the wine.

      Why wasn’t the experiment carried out in a controlled environment?
      >>To have a more realistic approach, the experiment was conducted under conditions wine is consumed every day.

      Why weren’t corks from other manufacturers included?
      >> There is a bulk of studies published upon others types of closures and corks,
      but we have found no study about sensory effects of Diam, which is produced by only one manufacturer.

      Why were the corks left to float in the wine when that is not a natural part of wine production or consumption?
      >> Because cork manufacturers including Diam do it in exactly the same way. Furthermore,
      bottles closed with Diam were also included in this trial. Just read the experimental design with some more attention.

      Why were the corks floating in opened wine for 32 hours – also not natural in the production or consumption of wine?
      >> Wrong. Not in opened wine; the vessels of both the treated wine and the reference were closed in order to prevent uncontrolled oxygen uptake.

      Why were the Diam samples all labeled A-H “2” rather than a random mix of numeric assignments (this may tend to introduce prejudice into the sampling).
      >> In a paired comparison test, you can label the samples however you want as long as they are randomized.

      While Mr Cordes may (or may not) be correct in his summary statements, the experiment is so flawed that it can not be taken seriously as any high school science student will tell you.
      >> Repeat the experiment with less what you call flaws, and the result will even be more evident.

  8. Jean Croissy says:

    Hi everyone, I have bottled my wines under diam and changed it a couple of years ago to natural cork because of the flaws Mr Cordes presented.
    Regards to all

  9. Dan Tudor says:

    We have been using the closures since 2003 and haven’t found a tainted, oxidized, bitter, or otherwise damaged bottle. NOT ONE BOTTLE!! The DIAM closures have proven to be flawless. In fact, every other winemaker that I’ve introduced the product to has started using them and with the same result. It’s the only closure other than screw cap with tin liner that we would use.

  10. Rolf Cordes says:

    Dear Dan,
    it’s easy. Give the same wine (screw cap) in two glasses. In one glass you give a Diam Cork. Lock the jars. Three days later you try both wines. Have the wines the same taste?
    Look into my study. Focus on the areas I have mentioned!
    You’ll generally no differences between wines closed with diam.
    This is because all the bottles are equally affected!

  11. Alex Sapsay says:

    I’ve made a trial with my wine. More that 10 different closures including DIAM. After 6 months – no perceptible difference. After 1 year (3 replicates) the wine under the natural cork was fine with no signs of bitterness and under DIAM some gluey odor appears that covers the aroma and in the taste it is definetely bitter… So, I tend to support Mr. Cordes with his statements…

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