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| − | {{Taxobox
| + | Brett info |
| − | | image = Brettanomyces.jpg
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| − | | image_width = 250px
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| − | | image_caption =
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| − | | regnum = [[Fungi]]
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| − | | phylum = [[Ascomycota]]
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| − | | subphylum = [[Saccharomycotina]]
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| − | | classis = [[Saccharomycetes]]
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| − | | ordo = [[Saccharomycetales]]
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| − | | familia = [[Pichiaceae]]
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| − | | genus = '''''Brettanomyces'''''
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| − | | subdivision_ranks = Species
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| − | | subdivision = ''B. anomalus ''<br />
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| − | ''[[Brettanomyces bruxellensis|B. bruxellensis]]''<br />
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| − | ''B. custersianus''<br />
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| − | ''B. naardenensis''<br />
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| − | ''B. nanus ''
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| − | }}
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| − | '''''Brettanomyces''''' is a [[spore|non-spore forming]] genus of [[yeast]] in the family [[Saccharomycetaceae]], and is often colloquially referred to as "''Brett''". The genus name '''''Dekkera''''' is used interchangeably with ''Brettanomyces'', as it describes the [[teleomorph]] or [[spore|spore forming]] form of the yeast. The cellular [[morphology (biology)|morphology]] of the yeast can vary from ovoid to long "sausage" shaped cells. The yeast is [[acidogenic]], and when grown on glucose rich media under aerobic conditions, produces large amounts of [[acetic acid]]. ''Brettanomyces'' is important to both the [[brewing]] and [[wine]] industries due to the sensory compounds it produces.
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| − | In the wild, ''Brettanomyces'' lives on the skins of fruit. The strain ''Brettanomyces claussenii'' was first classified at the [[Carlsberg Group|Carlsberg brewery]] in 1904 by N. Hjelte Claussen, who was investigating it as a cause of spoilage in English ales. The term ''Brettanomyces'' comes from the [[Greek (language)|Greek]] for "British fungus."
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| − | ==Wine==
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| − | {{see also|Yeast in winemaking}}
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| − | When ''Brettanomyces'' grows in wine it produces several compounds that can alter the palate and [[bouquet (wine)|bouquet]]. At low levels some [[winemaker]]s agree that the presence of these compounds has a positive effect on wine, contributing to complexity, and giving an aged character to some young red wines. Many wines even rely on ''Brettanomyces'' to give their distinctive character, such as [[Château Musar]]. However when the levels of the sensory compounds greatly exceed the [[sensory threshold]], their perception is almost always negative. The sensory threshold can differ between individuals, and some find the compounds more unattractive than others. While it can be desirable at lower levels, there is no guarantee that high levels will not be produced. As ''Brettanomyces'' can potentially spoil a wine it is generally seen as a [[Wine_spoilage#Microbiological|wine spoilage yeast]], and its presence in wine as a [[wine fault]].
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| − | Wines that have been contaminated with ''Brettanomyces'' taints are often referred to as "''Bretty''," "''metallic''," or as having "''Brett character''."<ref name=OCW-brett>{{Cite web|title=''Oxford Companion to Wine'' — Brettanomyces |url= http://www.winepros.com.au/jsp/cda/reference/oxford_entry.jsp?entry_id=446}} Also {{cite journal | author=Heresztyn, T | title=Formation of substituted tetrahydropyridines by species of Brettanomyces and Lactobacillus isolated from mousey wines | journal=American Journal of Enology and Viticulture | issue=37 | year=1986 | pages=127–32}}</ref> ''Brettanomyces'' taint in wine is also sometimes incorrectly identified as [[cork taint]].[http://www.spittoon.biz/cork_taint_and_brettanomyces.html]
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| − | ===Sensory compounds===
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| − | The compounds responsible contributing certain sensory characters to wine are;
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| − | *'''[[4-ethylphenol]]''': Band-aids, barnyard, horse stable, antiseptic
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| − | *'''[[4-ethylguaiacol]]''': Bacon, spice, cloves, smoky
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| − | *'''[[3-Methylbutanoic acid|isovaleric acid]]''': Sweaty saddle, cheese, rancidity
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| − | These compounds can impart completely different sensory properties to a wine when they are present in different ratios.
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| − | ===Origins in the winery===
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| − | ''Brettanomyces'' is most associated with barrel aged red wines, but has also been found in [[Chardonnay]] and [[Sauvignon blanc]]. In some cases the yeast has caused contamination in [[sparkling wine]]s produced by the [[Méthode champenoise]] when ''en tirage''. It is thought ''Brettanomyces'' can be introduced to a winery by insect vectors such as [[Drosophila melanogaster|fruit flies]], or by purchasing ''Brett'' contaminated wine barrels. The ability to [[metabolise]] the [[disaccharide]] [[cellobiose]], along with the irregular surface of a barrel interior, provide ideal conditions for ''Brettanomyces'' growth. Once the yeast is in a winery it is hard to eradicate and is spread readily by unsanitised equipment.
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| − | ===Control measures===
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| − | The growth of ''Brettanomyces'' is best controlled by the addition of [[sulfur dioxide]], to which the yeast is particularly sensitive. The addition of other sterilising compounds such as [[dimethyl dicarbonate]] often has a similar effect. Alternatively the wine can be bottled after sterile filtration, which physically removes the yeast. Wines that are vinified to low [[residual sugar]] levels, such as <1.0g/L, are also less likely to be spoiled as the main growth [[Substrate (biology)|substrate]] has been limited. However growth has been reported at levels below this and it is assumed that the yeast can use other substrates.
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| − | == Beer ==
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| − | In most [[beer]] styles ''Brettanomyces'' is viewed as a contaminant and the characteristics it imparts are considered unwelcome "off-flavours." However, in many styles, particularly certain traditional Belgian ales, it is appreciated and encouraged. [[Lambic]] and [[gueuze]] owe their unique flavour profiles to ''Brettanomyces'', as do wild yeast ''[[saison]]'' or farmhouse styles; and it is also found in [[Oud bruin|Oud Bruin]] and [[Flanders red ale]].<ref>{{cite news |title=Brews as Complex as Wine |first=Eric |last=Asimov |url=http://www.nytimes.com/2011/11/23/dining/sour-beers-review.html |newspaper=The New York Times |date=November 22, 2011 |accessdate=2011-11-24}}</ref>
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| − | Several American craft breweries use ''Brettanomyces'' in their beers. This use began with a renewed interest in Belgian style ales and later formed new styles altogether (Brewers Association, 2007 Great American Beer Festival Style Guidelines, section 13a, 16). Some breweries use 100% ''Brettanomyces'' for the fermentation of some of their beers, and omit ''[[Saccharomyces]]'' from the recipe. It is common for American brewers that use ''Brettanomyces'' to also include lactic acid producing bacteria such as ''[[Lactobacillus]]'', and ''[[Pediococcus]]'' in order to provide sourness to the beer.
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| − | While ''Brett'' is sometimes pitched into the fermenter, aging in wood barrels previously infected with ''Brettanomyces'' is another method used to impart the complexity and sourness contributed by these strains of yeast.
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| − | == See also ==
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| − | {{Portal|Fungi}}
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| − | * [[4-ethylguaiacol]]
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| − | * [[4-ethylphenol]]
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| − | * [[Brettanomyces bruxellensis]]
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| − | * [[Lambic]]
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| − | * [[Wine fault]]
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| − | ==References==
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| − | {{Refbegin}}
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| − | *{{cite book
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| − | | last = Fugelsang
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| − | | first = K. C.
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| − | | title = ''Wine Microbiology''
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| − | | year = 1997
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| − | | publisher = Champman & Hall
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| − | | location = U.S.A.
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| − | | isbn = 0-412-06611-4
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| − | | pages = 72–78
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| − | }}
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| − | {{Refend}}
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| − | ;Footnotes
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| − | {{Reflist}}
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| − | ==External links==
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| − | *[http://www.wineanorak.com/brettanomyces.htm Brettanomyces at wineanorak.com]
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| − | *[http://www.itv-midipyrenees.com/publications/fiches-pratiques/brettanomyces.php Brettanomyces at itv-midipyrenees.com]
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| − | *[http://www.nytimes.com/2010/06/02/dining/02sour.html Brewers Take Risks to Make Sour Beer at nytimes.com]
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| − | *[http://www.brettanomycesproject.com The Brettanomyces Project]
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| − | [[Category:Oenology]]
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| − | [[Category:Yeasts used in brewing]]
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| − | [[Category:Saccharomycetes]]
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| − | [[Category:Yeasts]]
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| − | [[de:Weinfehler#Brettanomyces]]
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