Newsletter April 2021
Is Cork Tannin Toxic?
Tannin is toxic. It kills all cells thus making tannin both antimicrobial but also harmful. By killing healthy human cells, tannin causes mouth lesions, digestive tract irritations and liver damage.
ProCork is the perfect way to keep using natural cork and stop Cork Tannin which even super critical CO2 cleaning cannot remove.
Cork Tannin from the ends of four different corks in 10% Alcohol
Compared to the 10% Alcohol in distilled water on the right
The antimicrobial need for Tannin in wine is reduced and possibly eliminated with the use of more hygienic wine making methods. When this is done the flavour alteration caused by Tannin can become the main concern of the winemaker instead of its antimicrobial effect.
Tannin is mostly noted for its negative flavour effects of astringency, bitterness, drying and its ability to dominate other flavours. But the right type of Tannin in the right concentration enhances the wine by giving a silky rolling mouthfeel and a bitter/sweet flavour effect. It is a delicate balance requiring “ripe” Tannin from the grape skin and the right amount of contact with grape seed and oak barrel Tannin.
But what is the point of all that effort if Cork Tannin can later flood your wine in a random way.
The variation in Cork Tannin between corks is amazingly high. In one study, Cork Tannin extracted into wine in 10 days from the best quality corks, ranged tenfold from 53,000 to 742,000 parts per billion*. At 200 parts per billion the astringency of Cork Tannin is noticeable, that is a few drops in an Olympic sized swimming pool.
The reason for such high variation is because Cork Tannin is produced in the bark of the cork tree as a deterrent to stop animals and insects eating the tree. The Tannin type and the Tannin concentration in the cork bark depends 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.
New research is indicating Cork Tannin can destroy the wine flavour as insidiously as TCA and even super-critical cleaning cannot remove the Cork Tannin. Jean-Marc Quarin, independent wine critic, published a comparison tasting and found Cork Tannin in super critically cleaned cork which “blocked the progress of the stimulation in the mouth and damaged the finish”.
The ProCork crystalline Tannin barrier is the perfect way to keep using natural cork and control the negative effects of Cork Tannin.
*time equivalence based on surface area and ppb based on mg of ellagitannins expressed as mg of ellagic acid extracted into 750 ml of wine.
S. Varea, M.C. Garcia-Vallejo, E. Cadahia, B. Fernandez de Simon “Polyphenols susceptible to migrate from cork stoppers to wine” Eur Food Res Technol (2001) 213:56–61
Contact: Dr Gregor Christie
Text +61 410717081