Changes

Jump to: navigation, search

Brettanomyces

116 bytes added, 19:51, 15 May 2016
no edit summary
''Brettanomyces'' strains may possess both alpha and beta glucosidases. These enzymes allow ''Brettanomyces'' strains to break down a broad range of sugars, including longer chain carbohydrate molecules (starch, dextrins, and cellulose/cellobiose), and to liberate glycosidically bound sugars which are unfermentable to ''Saccharomyces'' yeasts. <ref name="Steensels"></ref><ref>[http://www.scribd.com/doc/277758178/Insight-into-the-Dekkera-anomala-YV396-genome Insight into the Dekkera anomala YV396 genome. Samuel Aeschlimann. Self published on Eureka Brewing Blog. Spet 2015.]</ref>.
Extracellular and intracellular alpha-glucosidase activity has been shown to break down sugars up to 9 carbons in one strain of ''B. lambicus'', which is partly responsible for the over-attenuation of wort that some strains of ''Brettanomyces'' an achieve <ref name="yakobson_introduction"></ref>. Alpha glucosidases are the enzymes that allow them to break down maltose , turanose, melezitose, and trehalose, as well as dextrins (examples of these dextrins are such as maltotetraose and maltopentaose). These dextrins are left over after a normal ''Saccharomyces'' fermentation <ref name="Steensels"></ref>.
Glycosides are sugar molecules Beta-glycosidases can break down the beta-glycosidic bond in disaccharides (including cellulose, cellobiose , and gentiobiose) <ref name="ucdavis_chemwiki">[http://chemwiki.ucdavis.edu/Core/Organic_Chemistry/Carbohydrates/Disaccharides "Disaccharides." UC Davis Chemwiki. Retrieved 05/15/2016.]</ref>) , as well as glycosides. Glycosides are sugar molecules connected to other organic compounds such as acids, alcohols, and aldehydes which are flavor and aroma inactive due to the sugar molecule attached. By cleaving off the sugar molecule through beta-glucosidase activity, ''Brettanomyces'' species can liberate these compounds (called aglycones) into their aroma-active and flavor-active states, or states that may become flavor and aroma active through further modification <ref>Daenen et al., 2008. Evaluation of the glycoside hydrolase activity of a Brettanomyces strain on glycosides from sour cherry (Prunus cerasus L.) used in the production of special fruit beers. FEMS Yeast Res. 8, 1103-1114.</ref>. Therefore ''Brettanomyces'' strains are able to produce novel flavors and aromas from hops, fruits, and fruit pits that ''Saccharomyces'' yeasts cannot produce. In addition, the liberated aroma and flavor active compounds may be further processed by ''Brettanomyces'' through ester production or destruction pathways. See [[Brettanomyces#Glycosides_and_Beta-Glucosidase_Activity|Beta-Glucosidase Activity]] for more information.
Not all species are capable of consuming the same types of sugars. For example, ''B. anomalus'' (aka claussenii) are generally able to ferment lactose, but ''B. bruxellensis'' is generally not. Different strains within the same species may not be able to ferment the same types of sugars <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1279884332039778/ Lance Shaner experiment comparing the growth of various ''Brettanomyces spp'' on different growth mediums. 04/07/2016.]</ref><ref name="ncyc_searchbrett">[https://catalogue.ncyc.co.uk/catalogsearch/result/?q=brettanomyces National Collection of Yeast Cultures. Search for ''Brettanomyces''. Retrieved 04/07/2016.]</ref>. For example, some strains are not able to ferment maltose, which is almost half the sugar content of wort <ref>[https://eurekabrewing.wordpress.com/tag/sugar/ "Sugar composition of wort". Eureka Brewing Blog. Jan 13, 2015. Retrieved 04/07/2016.]</ref>. Such strains would not be a good choice for [[100%25_Brettanomyces_Fermentation|100% ''Brettanomyces'' fermentation]]. Currently, research into how well ''Brettanomyces'' strains ferment maltotriose has not been explored much by science, however one study found that ''B. custersianus'' can ferment maltotriose. More investigation into this possibility is needed <ref>[http://www.asbcnet.org/events/archives/2015Meeting/proceedings/Pages/54.aspx Determination of sugar metabolism profiles of non-traditional yeasts in the Saccharomyces and Brettanomyces families. J. D. Cook, W. A. DEUTSCHMAN. ASBC Proceeding. 2015.]</ref>. The below table is an example of the variety of sugar types that different strains/species of ''Brettanomyces'' banked at the [https://catalogue.ncyc.co.uk National Collection of Yeast Cultures] can ferment:
Retrieved from "http://www.milkthefunk.com/wiki/Special:MobileDiff/4900"

Navigation menu