Dekkera bruxellensis

''Brettanomyces bruxellensis'' (the anamorph of ''Dekkera bruxellensis'') is a yeast associated with the Senne valley near Brussels, Belgium. 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 and kriek, and is 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''. Macroscopically visible colonies look whitish and show a dome-shaped aspect, depending on the age and size.

''B. bruxellensis'' is increasingly being used by American craft brewers, especially in Maine, California and Colorado. Jolly Pumpkin Artisan Ales, Allagash Brewing Company, Port Brewing Company, Sierra Nevada Brewing Company, Russian River Brewing Company and New Belgium Brewing Company have all brewed beers fermented with ''B. bruxellensis''. The beers have a slightly sour, earthy character. Some have described them as having a "barnyard" or "wet horse blanket" flavor.Rocket Brewing Company on brettanomyces

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 ''Brettanomyces'' ("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

* Lambic
* Wine fault
* Yeast in winemaking

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

{{DEFAULTSORT:Brettanomyces bruxellensis
Yeasts
Oenology
Fungal grape diseases
Yeasts used in brewing
Saccharomycetes