29/10/2026
World Viticulture & Oenology Consulting 🍷🍷🍷
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Brettanomyces in w**e... What is it?
Brettanomyces, often abbreviated to "Brett," is a genus of unconventional yeasts, the most common species in w**e being Brettanomyces bruxellensis and Brettanomyces anomalus. These yeasts can develop during fermentation or aging, especially in red w**es and in poorly sanitized wooden barrels. Brettanomyces is known to produce aromatic compounds such as 4-ethylphenol and 4-ethylguaiacol, responsible for olfactory notes reminiscent of stables, leather, spices, smoke, or horse sweat.
To solve Brettanomyces problems in w**e, is increasing the sulfur dioxide sufficient? The answer is no!
When Brettanomyces contamination is confirmed, before taking action, it's important to understand the actual conditions of the w**e: pH, free SO₂, microbial population, and the possible presence of other spoilage microorganisms.
Sulfur dioxide plays an important antimicrobial role, especially through its molecular fraction.
However, this is highly dependent on pH: increasing the pH, while maintaining the same free SO₂, decreases the amount of molecular SO₂ that is actually active.
Above all, sulfur dioxide can control the microorganism, but it does not eliminate the volatile phenols that Brettanomyces has already produced.
Another option is the use of fungal chitosan, which can help reduce the Brettanomyces population. After treatment, the sedimented material must be separated from the w**e through appropriate physical procedures.
We can also intervene with membrane filtration, using systems with adequate microbiological retention and verifying their integrity.
Even in this case, however, it is essential to avoid subsequent contamination through pipes, tanks, and the bottling line.
For this reason, Brettanomyces is rarely managed simply by "adding more sulfur dioxide."
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