Brettanomyces bruxellensis
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B. bruxellensis
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| Brettanomyces bruxellensis Kufferath and von Laer
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Brettanomyces bruxellensis (the anamorph of Dekkera bruxellensis) is a yeast associated with and named after, the Senne valley near Brussels, Belgium. It is one of several members of the genus Brettanomyces, which were first classified at the Carlsberg brewery in 1904 by N. Hjelte Claussen, who was investigating it as a cause of spoilage in English ales, hence the name. Despite its Latin species name, B. bruxellensis is found all over the globe. In the wild, it is often found on the skins of fruit.
Beer production
B. bruxellensis plays a key role in the production of the typical Belgian beer styles such as Lambic, Flanders red ales, Gueuze, Kriek, and Orval, but it is not part of spontaneous fermentation biota. It is naturally found in the brewery environment living within oak barrels that are used for the storage of beer during the secondary conditioning stage. Here it completes the long slow fermentation or super-attenuation of beer, often in symbiosis with Pediococcus sp.
B. bruxellensis is increasingly being used by American craft brewers, especially in California and Colorado. Port Brewing Company, Sierra Nevada Brewing Company, Russian River Brewing Company, New Belgium Brewing Company and Rocket Brewing Company have all brewed beers fermented with B. bruxellensis. The beers have a slightly sour, earthy character. Some have described it as having a "barnyard" or "wet horse blanket" flavor.
Wine production
In the wine industry, B. bruxellensis is generally considered a spoilage yeast and it and other members of the genus are often referred to as brett. Its metabolic products can impart "sweaty saddle leather", "barnyard", "burnt plastic" or "band-aid" aromas to wine. Some winemakers in France, and occasionally elsewhere, consider it a desirable addition to wine, e.g., in Château de Beaucastel, but New World vintners generally consider it a defect. Some authorities consider brett to be responsible for 90% of the spoilage problems in premium red wines.
One defense against brett is to limit potential sources of contamination. It occurs more commonly in some vineyards than others, so producers can avoid purchasing grapes from such sources. Used wine barrels purchased from other vintners are another common source. Some producers sanitize used barrels with ozone. Others steam or soak them for many hours in very hot water, or wash them with either citric acid or peroxycarbonate.
If wine becomes contaminated by brett, some vintners sterile filter it, add SO2, or treat it with dimethyl dicarbonate. Both knowledge and experience are considered helpful in avoiding brett and the problems it can cause.
Biochemistry
B. bruxellensis contains the enzyme vinylphenol reductase.
See also
References
- "Breaking the mold", Wine Spectator,2006 (March 31), 30(16), pp. 99–100 & 103.
- Wild Brews: Beer Beyond the Influence of Brewer's Yeast, Jeff Sparrow, Brewers Publications, Coulder, Colo., 2005
- Rocket Brewing Company on brettanomyces
