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Ethyl-4-phenol
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 also a precursor to 4-vinylphenol. Natural occurrences In wine and beer, 4-EP is produced by the yeast '' Brettanomyces''. At concentrations greater than 140 μg/L (typical sensory threshold) it gives the wine aromas described as ''barnyard'', ''medicinal'', ''band-aids'', and ''mousy''. In certain Belgian beer styles, a high 4-EP level may be desirable; however, very high levels of the compound in wine can render it undrinkable. The level of 4-EP is roughly proportional to ''Brettanomyces'' concentration and activity, and can therefore be used as an indicator of the yeast's presence. There are significant differences between strains of ''Brettanomyces'' in their ability to produce 4-EP. 4-EP is also a component of castore ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Society Of Chemistry
The Royal Society of Chemistry (RSC) is a learned society (professional association) in the United Kingdom with the goal of "advancing the chemistry, chemical sciences". It was formed in 1980 from the amalgamation of the Chemical Society, the Royal Institute of Chemistry, the Faraday Society, and the Society for Analytical Chemistry with a new Royal Charter and the dual role of learned society and professional body. At its inception, the Society had a combined membership of 34,000 in the UK and a further 8,000 abroad. The headquarters of the Society are at Burlington House, Piccadilly, London. It also has offices in Thomas Graham House in Cambridge (named after Thomas Graham (chemist), Thomas Graham, the first president of the Chemical Society) where ''RSC Publishing'' is based. The Society has offices in the United States, on the campuses of The University of Pennsylvania and Drexel University, at the University City Science Center in Philadelphia, Pennsylvania, in both Beijing a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eurasian Beaver
The Eurasian beaver (''Castor fiber'') or European beaver is a beaver species that was once widespread in Eurasia, but was hunted to near-extinction for both its fur and castoreum. At the turn of the 20th century, only about 1,200 beavers survived in eight relict populations in Europe and Asia. It has been reintroduced to much of its former range, and now occurs from Spain, Central Europe, Great Britain and Scandinavia to a few regions in China and Mongolia. It is listed as least concern on the IUCN Red List, as it recovered well in most of Europe. It is extirpated in Portugal, Moldova, and Turkey. Taxonomy ''Castor fiber'' was the scientific name used by Carl Linnaeus in 1758, who described the beaver in his work ''Systema Naturae''. Between 1792 and 1997, several Eurasian beaver zoological specimens were described and proposed as subspecies, including: *''C. f. albus'' and ''C. f. solitarius'' by Robert Kerr in 1792 *''C. f. fulvus'' and ''C. f. variegatus'' by Johann Matth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 but at insufficient concentrations to be of issue. In fact, depending on perception, these concentrations may impart positive characters to the wine. However, when the concentration of these compounds greatly exceeds the sensory threshold, they replace or obscure the flavors and aromas that the wine should be expressing (or that the winemaker wants the wine to express). Ultimately the quality of the wine is reduced, making it less appealing and sometimes undrinkable.M. Baldy: ''"The University Wine Course", Third Edition, pp. 37-39, 69-80, 134-140. The Wine Appreciation Guild 2009 . There are many causes for the perception in wine faults, including poor hygiene at the winery, excessive or insufficient exposure of the wine to oxygen, exce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yeast In Winemaking
The role of yeast in winemaking is the most important element that distinguishes wine from fruit juice. In the absence of oxygen, yeast converts the sugars of the fruit into alcohol and carbon dioxide through the process of fermentation.Jeff Cox ''"From Vines to Wines: The Complete Guide to Growing Grapes and Making Your Own Wine"'' pp. 133–36 Storey Publishing 1999 The more sugars in the grapes, the higher the potential alcohol level of the wine if the yeast are allowed to carry out fermentation to dryness.D. Bird ''"Understanding Wine Technology"'' pp. 67–73 DBQA Publishing 2005 Sometimes winemakers will stop fermentation early in order to leave some residual sugars and sweetness in the wine such as with dessert wines. This can be achieved by dropping fermentation temperatures to the point where the yeast are inactive, sterile filtering the wine to remove the yeast or fortification with brandy or neutral spirits to kill off the yeast cells. If fermentation is unintenti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Growth Medium
A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Different types of media are used for growing different types of cells. The two major types of growth media are those used for cell culture, which use specific cell types derived from plants or animals, and those used for microbiological culture, which are used for growing microorganisms such as bacteria or fungi. The most common growth media for microorganisms are nutrient broths and agar plates; specialized media are sometimes required for microorganism and cell culture growth. Some organisms, termed fastidious organisms, require specialized environments due to complex nutritional requirements. Viruses, for example, are obligate intracellular parasites and require a growth medium containing living cells. Types The most common growth media ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vinyl Phenol Reductase
Vinylphenol reductase is an enzyme that catalyses the reaction : 4-vinylphenol + NAD+ + 3 H+ ⇔ 4-ethylphenol + NADH It is found in '' Brettanomyces bruxellensis'', a yeast responsible of the presence of ethyl phenols in wine formed from p-coumaric acid. See also * Wine chemistry Wine is a complex mixture of chemical compounds in a hydro-alcoholic solution with a pH around 4. The chemistry of wine and its resultant quality depend on achieving a balance between three aspects of the berries used to make the wine: their suga ... * Yeast in winemaking References External links Vinylphenol reductase on MetaCyc Oxidoreductases {{enzyme-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cinnamate Decarboxylase
4-Hydroxycinnamate decarboxylase is an enzyme that uses ''p''-coumaric acid to produce 4-ethylphenol. ''p''-Coumaric acid is the precursor of 4-ethylphenol produced by the yeast '' Saccharomyces'' and '' Brettanomyces'' in wine. The yeast converts this to 4-vinylphenol via the enzyme cinnamate decarboxylase. 4-Hydroxycinnamate decarboxylase can also be induced in bacteria species such as '' Klebsiella oxytoca'' and works also with p-coumaric acid analogs such as caffeic acid, ferulic acid and E-2,4-dihydroxycinnamic acid. References See also * Wine chemistry Wine is a complex mixture of chemical compounds in a hydro-alcoholic solution with a pH around 4. The chemistry of wine and its resultant quality depend on achieving a balance between three aspects of the berries used to make the wine: their suga ... {{enzyme-stub Hydroxycinnamic acids metabolism EC 4.1.1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North American Beaver
The North American beaver (''Castor canadensis'') is one of two Extant taxon, extant beaver species, along with the Eurasian beaver (''Castor fiber''). It is native to North America and introduced in South America (Patagonia) and Europe (primarily Finland and Karelia). In Canada and the United States, the species is often referred to simply as "beaver", though this causes some confusion because another distantly related rodent, ''Aplodontia rufa'', is often called the "mountain beaver". Other vernacular names, including American beaver and Canadian beaver, distinguish this species from the other Extant taxon, extant beaver species, ''Castor fiber'', which is native to Eurasia. The North American beaver is one of the official national wildlife of Canada symbols and is the official state mammal of Oregon and New York (state), New York. Taxonomy Evolution The first fossil records of beaver are 10 to 12 million years old in Germany, and they are thought to have migrated to North Amer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
