''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 constitut ...
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 suppl ...
, and is often colloquially referred to as "Brett". The genus name ''Dekkera'' is used interchangeably with ''Brettanomyces'', as it describes the
teleomorph
In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota:
*Teleomorph: the sexual reproductive stage (morph), typically a fruiting body.
*Anamorph: an ase ...
or
spore forming form of the yeast, but is considered deprecated under the
one fungus, one name change. The cellular
morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
* Morphology (archaeology), study of the shapes or forms of artifacts
* Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
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, using ...
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 component ...
. ''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, fermenting the resulting sweet liquid with Yeast#Beer, yeast. It may be done in a brewery ...
and
wine
Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
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 Paper ...
''" 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
Carlsberg A/S (; ) is a Danish multinational brewer. Founded in 1847 by J. C. Jacobsen, the company's headquarters is in Copenhagen, Denmark. Since Jacobsen's death in 1887, the majority owner of the company has been the Carlsberg Foundation. T ...
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
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
for "British fungus".
Wine
When ''Brettanomyces'' grows in wine it produces several compounds that can alter the palate and
bouquet. At low levels some
winemaker
A winemaker or vintner is a person engaged in winemaking. They are generally employed by wineries or wine companies, where their work includes:
*Cooperating with viticulturists
*Monitoring the maturity of grapes to ensure their quality and to deter ...
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 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 Ga ...
. 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 probabi ...
, 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
The role of yeast in winemaking is the most important element that distinguishes wine from fruit juice. In the :wikt:anaerobic, absence of oxygen, yeast converts the sugar in wine, sugars of the fruit into ethanol, alcohol and carbon dioxide throu ...
, and its presence in wine as a
wine fault
A wine fault or defect is an unpleasant characteristic of a wine often resulting from poor winemaking practices or storage conditions, and leading to wine spoilage. Many of the compounds that cause wine faults are already naturally present in wine ...
.
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
Cork taint is a broad term referring to a wine fault characterized by a set of undesirable smells or tastes found in a bottle of wine, especially spoilage that can only be detected after bottling, aging and opening. Though modern studies have sh ...
.
Sensory compounds
The compounds responsible contributing certain sensory characters to wine are;
*
4-ethylphenol
Ethylphenol (4-EP) is an organic compound with the formula C2H5C6H4OH. It is one of three isomeric ethylphenols. A white solid, it occurs as an impurity in xylenols and as such is used in the production of some commercial phenolic resins. It is ...
: 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 French wine, France, but is now grown wherever wine is produced, from English wine, Englan ...
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 wine
Sparkling wine is a wine with significant levels of carbon dioxide in it, making it fizzy. While the phrase commonly refers to champagne, European Union countries legally reserve that term for products exclusively produced in the Champagne regi ...
s 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
Fruit fly may refer to:
Organisms
* Drosophilidae, a family of small flies, including:
** ''Drosophila'', the genus of small fruit flies and vinegar flies
** ''Drosophila melanogaster'' or common fruit fly
** ''Drosophila suzukii'' or Asian fruit ...
, or by purchasing ''Brett''-contaminated wine barrels. The ability to
metabolise
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
the
disaccharide
A disaccharide (also called a double sugar or ''biose'') is the sugar formed when two monosaccharides are joined by glycosidic linkage. Like monosaccharides, disaccharides are simple sugars soluble in water. Three common examples are sucrose, lact ...
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 hyd ...
, 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 activ ...
, to which the yeast is particularly sensitive. The addition of other sterilising compounds such as
dimethyl dicarbonate
Dimethyl dicarbonate (DMDC) is a colorless liquid and a pungent odor at high concentration at room temperature. It is primarily used as a beverage preservative, processing aid, or sterilant ( INS No. 242) being highly active against typical bever ...
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, whil ...
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 ales, it is appreciated and encouraged.
Gueuze
Gueuze (Dutch ''geuze'', ; French ''gueuze'', ) is a type of lambic, a Belgian beer. It is made by blending young (1-year-old) and old (2- to 3-year-old) lambics, which is bottled for a second fermentation. Because the young lambics are not ...
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 beers ...
beers owe their unique flavour profiles to ''Brettanomyces'', as do wild yeast ''
saison
Saison ( French, "season," ) is a pale ale that is highly carbonated, fruity, spicy, and often bottle conditioned. It was historically brewed with low alcohol levels, but modern productions of the style have moderate to high levels of alcohol. ...
'' 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 weeks ...
and
Flanders red ale
Flanders red ale or Flemish red-brown, is a style of sour ale brewed in West Flanders, Belgium.
Flanders red ale is fermented with organisms other than ''Saccharomyces cerevisiae'', especially ''Lactobacillus'', which produces a sour character ...
.
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 diver ...
'' and ''
Pediococcus
''Pediococcus'' is a genus of gram-positive lactic acid bacteria, placed within the family of Lactobacillaceae. They usually occur in pairs or tetrads, and divide along two planes of symmetry, as do the other lactic acid cocci genera ''Aerococcu ...
'' 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
Ethylphenol (4-EP) is an organic compound with the formula C2H5C6H4OH. It is one of three isomeric ethylphenols. A white solid, it occurs as an impurity in xylenols and as such is used in the production of some commercial phenolic resins. It is ...
* ''
Brettanomyces bruxellensis
''Brettanomyces bruxellensis'' (the anamorph of ''Dekkera bruxellensis'') is a yeast associated with the Zenne, Senne valley near Brussels, Belgium. Despite its Latin species name, ''B. bruxellensis'' is found all over the globe. In the wild, it ...
''
*
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 beers ...
*
Wine fault
A wine fault or defect is an unpleasant characteristic of a wine often resulting from poor winemaking practices or storage conditions, and leading to wine spoilage. Many of the compounds that cause wine faults are already naturally present in wine ...
References
*
;Footnotes
External links
Brettanomyces at Milk the Funk Wiki
{{Taxonbar, from=Q2411973
Oenology
Yeasts used in brewing
Saccharomycetes
Yeasts
de:Weinfehler#Brettanomyces