How to avoid brettanomyces post vinification process
Brettanomyces contamination becomes increasingly difficult to control as temperatures and environmental pressures rise, leading to an increase in the cellular metabolism of microorganisms.
This can result in their proliferation in wine and the onset of contamination problems in the cellar. The months after harvest are critical for the development of Brettanomyces. During this period, they emerge from their dormant phase and grow exponentially, causing the release of volatile phenolics during their stationary phase – 30 to 60 days after the onset of population growth (K. Fugelsang, 2003).
One complication with Brettanomyces is the appearance of undesirable odors that cause a deterioration in wine quality. Brettanomyces represents one of the main threats to wine quality and its development can lead to the formation of undesirable compounds, particularly ethyl phenols and acetic acid, which are responsible for unpleasant odors of animal notes such as horse, stable, and leather, and pharmaceutical notes such as bandage or medicinal, compromising the flavor profile of wine. This yeast is everywhere and can even develop under harsh conditions such as high levels of sulfur dioxide, high alcohol, nutritional deficiency, low pH, etc.
Effective Preventive and Treatment Tool: Activated Chitosan
Traditionally, the main tool to control Brettanomyces has been the use of sulfur dioxide (SO₂). However, to be effective, the concentration of molecular SO₂ must be maintained at a minimum of 0.4 mg/L, or more depending on the strain. This may require high doses of free SO₂, especially in wines with high pH.
To prevent the formation of undesirable odors, it is necessary to control the development of Brettanomyces during different times of year, especially at the end of alcoholic fermentation.
The elimination of the microorganism before the exponential phase of its population growth (before 60 days from the dormancy phase) is recommended.
The fastest and most effective method to detect and quantify this yeast is PCR. Once the presence of Brettanomyces is detected, Enartis recommends the use of EnartisStab MICRO M, a preparation of activated chitosan.
Chitosan, derived from Aspergillus niger, possesses a positive surface charge that interacts with microorganism cell membranes, leading to their inactivation. This chitosan is enhanced by activation with organic acids, which amplifies the antimicrobial efficacy.
Benefits of Activated Chitosan
Wine Trials: Treatment Results
This trial shows the application of different doses of EnartisStab MICRO M to a red wine. Seven days after treatment with 10 g/hL, the entire population of Brettanomyces was eliminated. After 15 days, even the half dose (5 g/hL) eliminated the presence of Brettanomyces.
In a trial conducted at winery scale, 8 g/hL of EnartisStab MICRO M reduced Brettanomyces content in only 4 days.
The same situation is evident in another case study in which, 7 days after treatment, the Brettanomyces population is also nondetectable when plated.
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| Control | 7 days after treatment (15g/hL EnartisStab MICRO M) |
The required contact time of EnartisStab MICRO M varies depending on the concentration of Brettanomyces, turbidity, temperature, wine characteristics, and the time needed for decontamination.
Treatment is generally effective after 7-10 days of contact time. To verify the effectiveness of the treatment, it is advised to perform tests using traditional methods such as plating since PCR also quantifies nonviable cells.
How can we eliminate volatile phenols if they are already present?
If preventing contamination has failed and curative treatment with activated chitosan was carried out, unwanted odors and flavors can be reduced using an effective fining treatment, depending on the concentration and type of volatile phenols.
Enartis recommends the use of FENOL FREE, a carbon-based fining agent that removes volatile phenols from wine.
Below, in a wine with a high concentration of volatile phenols due to Brettanomyces contamination, the two-stage FENOL FREE treatment resulted in a final reduction of 76% for ethylphenol (EF) and 82% for ethylguaiacol (EG).
