Brettanomyces effect

Fugelsang, K. C., Zoecklein, B. W. (2003) Population dynamics and effects of Brettanomyces bruxellensis strains on Pinot noir (Vitis vinifera L.) wines. American Journal of Enology and Viticulture, 54, 294-300. 

Using Brettanomyces claussenii, Custers showed glucose fermentation is inhibited under anaerobic conditions. Glucose was fermented more rapidly under aerobic than anaerobic conditions. He named this inhibitory effect a negative Pasteur effect". Aerobic conditions activated the fermentation of glucose to produce ethyl alcohol, carbon dioxide, and "a considerable amount of acetic acid". Only ethanol and carbon dioxide were produced under anaerobic conditions acetic acid was not. 

In 1961 Wiken (11) showed evidence of a negative Pasteur effect as characteristic of all yeast in the genus Brettanomyces. In 1966 Scheffers (12) described this inhibition of alcoholic fermentation under anaerobic conditions as a consequence of the net reduction of NAD" to NADH in Brettanomyces yeast cells he called this a "Custers effect". 

Burk (13) provided an extensive history of the literature up to 1939 on the mechanism hypotheses of a Pasteur effect in biological systems. For further confirmational and mechanistic work on a Custers effect in Brettanomyces, the articles by Scheffers (14), Carrascosa (15), and Wijsman (16) should be consulted. 

Du Toit, W.J., Pretorius, I.S., and Lonvaud-Funel, A. 2005. The effect of sulphur dioxide and oxygen on the viability and culturability of a strain of Acetobacter pasteurianus and a strain of Brettanomyces bruxellensis isolated from wine. Journal of Applied Microbiology 98 862-871. 

The rhythm of racking must also be taken into account. In a cellar where the barrels are stored with the bung on the side, racking and adjustment of the free SO2 level, accompanied by disinfection of the barrels, must be carried out every 3 months during the first year of barrel aging. If racking is delayed, as shown in Table 8.9, the quantity of free SO2 remaining at the end of the period is too small to protect the wine effectively. The wine is subject to rapid contamination by Brettanomyces yeasts and its ethyl-phenol content inevitably increases. 

Wijsman, M. R., van Dijken, J. P., van Kleeff, B. H., Scheffers, W. A. (1984). Inhibition of fermentation and growth in batch cultures of the yeast Brettanomyces intermedius upon a shift from aerobic to anaerobic conditions (Custers effect). Antonie van Leeuwenhoek, 50(2), 183-192. 

Aguilar Usganga, M.G., M.-L. Delia, and P. Strehaiano. 2003. Brettanomyces bruxellensis effect of oxygen on growth and acetic acid production. Appl. Microbiol. Biotechnol. 61 157—162. 

In an unsulfited and non-inoculated must, contamination yeasts can begin to develop within a few hours of filling the tank. Apiculated yeasts (Kloechera, Hanseniaspora) are the most frequently encountered. Aerobic yeasts also develop (Candida, Pichia, Hansenula), producing acetic acid and ethyl acetate. Brettanomyces and its characteristic animal-like odors are rare in must. Although such yeasts can be relatively resistant to sulfur dioxide (Fleet, 1992), sulfiting followed by inoculating with a selected strain of Saccharomyces cerevisiae constitute, in practice, an effective means of avoiding contamination (Section 3.5.4). 

DMDC has proved effective not only on fermentation yeasts, but also on those responsible for contamination (Brettanomyces, Volume 2,... 

Microbiological stabilization of wines is necessary to avoid the many problems that may be caused by microorganisms. Lysozyme does not protect sweet wines from fermenting again or eliminate contaminant yeasts (Brettanomyces), nor is it effective against acetic bacteria, which cause volatile acidity in aerated wines. 

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