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Cork Tannin Astringency – could it be a bigger problem than TCA?


A finest quality cork showing signs of structural collapse after having its tannin extracted by wine for 15 years

and a solution of 10% alcohol in distilled water after it has been in contact with cork for 2 weeks.

ProCork’s membrane technology is the only answer!


November 2020 Newsletter

Cork tannin varies from cork to cork thus creating a lucky dip (or unlucky dip) for the wine drinker. 

Recent commentary is now suggesting that cork tannin could interfere with the taste buds and negatively alter wine drinkers’ ability to taste the true wine flavour. This is strangely reminiscent of the more insidious effects of TCA. 




Jean-Marc Quarin is an independent Bordeaux based wine critic and is the 2011 winner of the Nadine de Rothschild Prize for his book “Guide Quarin des vins de Bordeaux” where he described his unique tasting method “Palate over Nose”.

Quarin has now published in his Chronicles on 21 October, 2020, the comparison "Bouchons techniques: DIAM versus ProCork”. He preferred ProCork because he identified the presence of bitter and tannic effects in DIAM 10 which “blocked the progress of the stimulation in the mouth and damaged the finish”. He did not detect these negative effects in ProCork. 

Chemical analysis by SENSENET, a French sensory company, has confirmed that cork tannin was indeed extracted from the DIAM 10 cork into the wine causing the negative effect. 

Tannin is produced in great quantities in the bark of the cork tree as a deterrent to stop animals and insects eating the tree. Generally, tannin induces a negative response when consumed. It can be instantaneous like astringency or a bitter and unpleasant taste and it can have a delayed response related to anti-nutritional and toxic effects. 

The tannin type and concentration in the cork bark will depend on the environmental stress that a particular section of bark is subjected to as well as genetic effects associated with each individual tree. This is the source of its variability in cork stoppers.

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Cork Tannin from the ends of four different corks in 10% Alcohol

Compared to the 10% Alcohol in distilled water on the right

Wine makers go to great lengths to ripen the grape tannin and select the right oak barrel tannin. They control the concentration of these tannins through skin contact and barrel time while always being conscious of the terroir of their wine. Harsh and bitter cork tannin alters the wine drinkers’ ability to taste these true flavours and to have it uncontrollably added afterwards in different amounts to different bottles is clearly not in the winemakers’ interest nor the consumers.

ProCork's tannin barrier technology is the only solution available to ensure wine is protected from cork tannin blocking the stimulation of the taste buds.

Contact: Dr Gregor Christie


               Phone +61 410717081

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