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''Brettanomyces'' is a non-spore forming genus of
yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constit ...
in the family
Saccharomycetaceae The Saccharomycetaceae are a family of yeasts in the order Saccharomycetales that reproduce by budding. Species in the family have a cosmopolitan distribution, and are present in a wide variety of habitats, especially those with a plentiful sup ...
, and is often colloquially referred to as "Brett". The genus name ''Dekkera'' is used interchangeably with ''Brettanomyces'', as it describes the teleomorph or spore forming form of the yeast, but is considered deprecated under the one fungus, one name change. The cellular morphology of the yeast can vary from ovoid to long "sausage" shaped cells. The yeast is
acidogenic Acidogenesis is the second stage in the four stages of anaerobic digestion: * Hydrolysis: A chemical reaction where particulates are solubilized and large polymers converted into simpler monomers; * Acidogenesis: A biological reaction where simple ...
, and when grown on
glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...
rich media under aerobic conditions, produces large amounts of
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main componen ...
. ''Brettanomyces'' is important to both the
brewing Brewing is the production of beer by steeping a starch source (commonly cereal grains, the most popular of which is barley) in water and fermenting the resulting sweet liquid with yeast. It may be done in a brewery by a commercial brewer ...
and
wine Wine is an alcoholic drink typically made from Fermentation in winemaking, fermented grapes. Yeast in winemaking, Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different ...
industries due to the sensory compounds it produces. In the wild, ''Brettanomyces'' lives on the skins of fruit.


History

In 1889, Seyffert of the Kalinkin Brewery in St. Petersburg was the first to isolate a "''
Torula Torula (''Cyberlindnera jadinii'') is a species of yeast. Use Torula, in its inactive form (usually labeled as torula yeast), is widely used as a flavoring in processed foods and pet foods. It is often grown on wood liquor, a byproduct of pape ...
''" from English beer which produced the typical "English" taste in lager beer, and in 1899 JW Tullo at Guinness described two types of "secondary yeast" in Irish stout. However N. Hjelte Claussen at the Carlsberg brewery was the first to publish a description in 1904, following a 1903 patent (UK patent GB190328184) that was the first patented microorganism in history. The term ''Brettanomyces'' comes from the Greek for "British fungus".


Wine

When ''Brettanomyces'' grows in wine it produces several compounds that can alter the palate and bouquet. At low levels some winemakers 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 Chateau Musar is the name of a Lebanese winery in Ghazir, Lebanon, north of the capital Beirut. Musar grapes grow in the Beqaa Valley, a fertile sunny valley at an elevation of , situated east of Beirut. History The winery was established by G ...
. However, when the levels of the sensory compounds greatly exceed the
sensory threshold In psychophysics, sensory threshold is the weakest stimulus that an organism can sense. Unless otherwise indicated, it is usually defined as the weakest stimulus that can be detected half the time, for example, as indicated by a point on a proba ...
, 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 yeast, and its presence in wine as a wine fault. Wines that have been contaminated with ''Brettanomyces'' taints are often referred to as "''Bretty''", "''metallic''", or as having "''Brett character''".
Also
''Brettanomyces'' taint in wine is also sometimes incorrectly identified as cork taint.


Sensory compounds

The compounds responsible contributing certain sensory characters to wine are; * 4-ethylphenol: Band-aids, barnyard, horse stable, antiseptic * 4-ethylguaiacol: Bacon, spice, cloves, smoky * isovaleric acid: Sweaty saddle, cheese, rancidity These compounds can impart completely different sensory properties to a wine when they are present in different ratios.


Origins in the winery

''Brettanomyces'' is most associated with barrel aged red wines, but has also been found in
Chardonnay Chardonnay (, , ) is a green-skinned grape variety used in the production of white wine. The variety originated in the Burgundy wine region of eastern France, but is now grown wherever wine is produced, from England to New Zealand. For new ...
and
Sauvignon blanc is a green-skinned grape variety that originates from the Bordeaux region of France. The grape most likely gets its name from the French words ''sauvage'' ("wild") and ''blanc'' ("white") due to its early origins as an indigenous grape in ...
. In some cases the yeast has caused contamination in sparkling wines produced by the
méthode champenoise Sparkling wine production is the method of winemaking used to produce sparkling wine. The oldest known production of sparkling wine took place in 1531 with the ''ancestral method''. Pressure and terminology In popular parlance and also in the ...
when ''en tirage''. It is thought ''Brettanomyces'' can be introduced to a winery by insect vectors such as fruit flies, or by purchasing ''Brett''-contaminated wine barrels. The ability to metabolise the disaccharide
cellobiose Cellobiose is a disaccharide with the formula (C6H7(OH)4O)2O. It is classified as a reducing sugar. In terms of its chemical structure, it is derived from the condensation of a pair of β-glucose molecules forming a β(1→4) bond. It can be h ...
, 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.


Control measures

The growth of ''Brettanomyces'' is best controlled by the addition of
sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic a ...
, 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 The subjective sweetness of a wine is determined by the interaction of several factors, including the amount of sugar in the wine, but also the relative levels of alcohol, acids, and tannins. Sugars and alcohol enhance a wine's sweetness, whi ...
levels, such as <1.0g/L, are also less likely to be spoiled as the main growth substrate has been limited. However growth has been reported at levels below this and it is assumed that the yeast can use other substrates.


Beer

In most
beer Beer is one of the oldest and the most widely consumed type of alcoholic drink in the world, and the third most popular drink overall after water and tea. It is produced by the brewing and fermentation of starches, mainly derived from ce ...
styles ''Brettanomyces'' is typically viewed as a contaminant and the characteristics it imparts are considered unwelcome "off-flavours". However, in certain styles, particularly certain traditional
Belgian ale Beer in Belgium includes pale ales, lambics, Flemish red ales, sour brown ales, strong ales and stouts. In 2018, there were 304 active breweries in Belgium, including international companies, such as AB InBev, and traditional breweries includi ...
s, it is appreciated and encouraged. Gueuze and other
lambic Lambic () is a type of beer brewed in the Pajottenland region of Belgium southwest of Brussels and in Brussels itself since the 13th century. Types of lambic beers include gueuze, kriek lambic and framboise. Lambic differs from most other be ...
beers 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 (Old Brown), also known as Flanders Brown, is a style of beer originating from the Flemish region of Belgium. The Dutch name refers to the long aging process, up to a year. It undergoes a secondary fermentation, which takes several week ...
and Flanders red ale. In Orval ''Brettanomyces'' is added before the final bottle fermentation. Several American craft breweries intentionally 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 ''Saccharomyces'' is a genus of fungi that includes many species of yeasts. ''Saccharomyces'' is from Greek σάκχαρον (sugar) and μύκης (fungus) and means ''sugar fungus''. Many members of this genus are considered very important in f ...
'' from the recipe. Some American brewers that use ''Brettanomyces'' may also include lactic acid producing bacteria such as ''
Lactobacillus ''Lactobacillus'' is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically div ...
'' and '' Pediococcus'' in order to provide sourness to the beer. While ''Brett'' is sometimes pitched into the fermenter, aging in wood barrels previously inoculated with ''Brettanomyces'' is another method used to impart the complexity contributed by these strains of yeast.


See also

* 4-ethylguaiacol * 4-ethylphenol * '' Brettanomyces bruxellensis'' *
Lambic Lambic () is a type of beer brewed in the Pajottenland region of Belgium southwest of Brussels and in Brussels itself since the 13th century. Types of lambic beers include gueuze, kriek lambic and framboise. Lambic differs from most other be ...
* Wine fault


References

* ;Footnotes


External links


Brettanomyces at Milk the Funk Wiki
{{Taxonbar, from=Q2411973 Oenology Yeasts used in brewing Saccharomycetes Yeasts de:Weinfehler#Brettanomyces