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Brettanomyces

65 bytes added, 11:16, 4 April 2018
clarification on spore forming version of Brett
[[Image:Brettanomyces.jpg|thumb|200px|right|Brettanomyces]][[File:Brett-aroma-wheel.jpeg|thumb|200px|right|Brett Aroma Wheel by Dr. Linda Bisson and Lucy Joseph at UC Davis]]
'''Brettanomyces''', also referred to by brewers as "Brett" or "Bretta", is Greek for "British Fungus" and is a yeast that was originally thought of as an important yeast for producing the character of some 17th century and prior English ales. Since the wide adoption of pure cultures of ''Saccharomyces cerevisiae'' and ''S. pastorianus'' in the brewing and wine industries starting in the late 1800's, ''Brettanomyces'' has been mostly viewed as a spoilage yeast, except in Belgian lambic, Flanders red/brown beers, and a handful of styles of wine. More recently ''Brettanomyces'' has gained popularity in the United States (and subsequently the brewing industries of other countries) as a yeast that can contribute desirable and novel characteristics to beer and other alcoholic beverages. The genus name ''Dekkera'' is used interchangeably with ''Brettanomyces'', as it describes the teleomorph or spore -forming form of the yeast , although this form is extremely rare or perhaps even non-existent <ref>[http://en.wikipedia.org/wiki/Brettanomyces Wikipedia. Brettanomyces. Retrieved 2/24/2015.]</ref>. Known for it's its barnyard, fecal, horsey, metallic or Band-Aid flavors, ''Brettanomyces'' continues to be unwelcome in many breweries and most wineries. However, ''Brettanomyces'' also produces high levels of fruity esters that are desirable in some styles like saison, [[lambic]], and American sour beers. ''Brettanomyces'' can also form a [[pellicle]] during fermentation. See ''[[Lactobacillus]]'', ''[[Pediococcus]]'', ''[[Saccharomyces]]'', [[Mixed Cultures]], and [[Nonconventional Yeasts and Bacteria]] charts for other commercially available cultures.
==Introduction of Characteristics and Taxonomy==
Although first isolated in 1889 and again in 1899 by scientists at Guinness, the discovery of ''Brettanomyces'' was first publicly published by Hjelte Claussen in 1904 after he cultured it in 1903 from English beers that exhibited a sluggish secondary fermentation <ref>[http://barclayperkins.blogspot.com/2013/06/when-was-brettanomyces-discovererd.html "When was Brettanomyces discovererddiscovered?" Ron Pattenson. Shut Up About Barclay Perkins blog. 06/29/2013. retrieved 08/18/2016.]</ref>. At the time of discovery, Claussen was aiming to recreate the flavor profile of traditional English ales by fermenting them with pure cultures of ''Saccharomyces'', and either pitching pure cultures of his newly discovered ''Brettanomyces'' yeast along with ''Saccharomyces'', or as he preferred, after the primary fermentation of ''Saccharomyces'' <ref>[https://www.facebook.com/download/448702618652516/GB190328184A.pdf "Improvements in and connected with the Manufacture of English Beers or Malt Liquors and in the Production of Pure Yeast Cultures for use therein." Patent application by Hjelte Claussen for ''Brettanomyces''. A.D. 1903.]</ref>. Although Claussen saw the character from ''Brettanomyces'' as a desirable character in ales and identified its character as a quality of traditional English ales, at some point ''Brettanomyces'' became identified as a contaminate in wineries and breweries due to some of the phenols, acids, and haze that it sometimes produces. These phenols and acids have generally been described as "barnyard", "burnt plastic", "wet animal", "fecal", and "horse sweat", although some tasters describe these flavors with different terminology because they perceive certain flavor compounds differently while some other tasters simply cannot detect certain flavor compounds at all <ref name="smith_divol_2016"></ref><ref name="Schifferdecker">[http://onlinelibrary.wiley.com/doi/10.1002/yea.3023/pdf The wine and beer yeast Dekkera bruxellensis. Anna Judith Schifferdecker, Sofia Dashko, Olena P. Ishchuk, and Jure Piškur. 7 July 201.]</ref><ref name="Lucy_2015">[http://www.ajevonline.org/content/66/3/379 Brettanomyces bruxellensis Aroma-Active Compounds Determined by SPME GC-MS Olfactory Analysis. C.M. Lucy Joseph, Elizabeth A. Albino, Susan E. Ebeler, Linda F. Bisson. 2015.]</ref>. The general viewpoint of brewers (other than Lambic and Flanders red/brown brewers in Belgium) and vintners that ''Brettanomyces'' is primarily a spoilage organism held for many decades, and still holds in most cases. More recently the positive flavor components that have been identified in ''Brettanomyces'' beer such as pineapple, stone fruits, and to some degree acetic acid, have regained popularity with brewers outside of Belgium. Wine tasters have also described wines with certain flavor compounds derived from ''Brettanomyces'' as positive characteristics of wine. It is important to keep in mind that individual tasters on tasting panels describe some flavor compounds as "negative" while others describe them as "positive" (and sometimes a mixed response is given by a taster in regards to a certain flavor compound), and this discrepancy in interpretations of ''Brettanomyces'' derived flavor compounds appears to be based on personal preference and experience. In some cases, for example for vinyl phenols, low levels that are not detectable by some people, but detected by others contribute positively to wine, while higher amounts contribute negatively. Thus, lower intensity of some flavor compounds can be seen as more desirable. Overall, the enjoyment or displeasure of the various flavor compounds produced by ''Brettanomyces'' and at certain levels is completely subjective <ref name="Lucy_2015" />.
It is common in scientific literature to see the names ''Dekkera'' and ''Brettanomyces'' used as the genus name, with ''Dekkera'' being the [https://en.wikipedia.org/wiki/Teleomorph,_anamorph_and_holomorph teleomorph] version and ''Brettanomyces'' being the [https://en.wikipedia.org/wiki/Teleomorph,_anamorph_and_holomorph anamorph]. There are five species within the genus of Brettanomyces: ''B. anomalus'', ''B. bruxellensis'', ''B. custersianus'', ''B. nanus'', and ''B. naardenensis'' (one study on the genetics of ''B. nanus'' from 1990 classified ''B. nanus'' as belonging to another genus of yeast called ''Eeniella'', however this has not been agreed upon in more recent studies <ref>[http://onlinelibrary.wiley.com/doi/10.1002/yea.320060403/full Dekkera, Brettanomyces and Eeniella: Electrophoretic comparison of enzymes and DNA–DNA homology. Maudy Th. Smith, M. Yamazaki, G. A. Poot. 1990.]</ref>). The species known as ''B. intermedius'' and ''B. lambicus'' are considered synonyms of ''B. bruxellensis'' <ref name="Agnolucci_2017">[https://link.springer.com/article/10.1007/s11274-017-2345-z Brettanomyces bruxellensis yeasts: impact on wine and winemaking. Monica Agnolucci, Antonio Tirelli, Luca Cocolin, Annita Toffanin. 2017.]</ref>. Of these five species, only ''B. anomalus'' and ''B. bruxellensis'' have been identified to have a teleomorph version. In their teleomorph version they are referred to as ''Dekkera anomala'' and ''Dekkera bruxellensis'' <ref name="smith_divol_2016"></ref><ref name="Schifferdecker"></ref><ref name="Steensels"></ref><ref>[http://aem.asm.org/content/80/14/4398.full Assessing Genetic Diversity among Brettanomyces Yeasts by DNA Fingerprinting and Whole-Genome Sequencing. Sam Crauwels, Bo Zhu, Jan Steensels, Pieter Busschaert, Gorik De Samblanx, Kathleen Marchald, Kris A. Willems, Kevin J. Verstrepen and Bart Lieven. 2014.]</ref>. All of the other names such as the ones often used by yeast labs are derived by old nomenclature that is no longer used ([http://www.sciencedirect.com/science/article/pii/S0168160515001865#t0005 click here] for a table that lists old and new taxonomical nomenclature). Most ''Brettanomyces'' cultures from brewer's yeast labs are classified genetically as ''B. bruxellensis'' or ''B. anomalus''.

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