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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 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 castoreum, the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 sugar content, acidity and the presence of secondary compounds. Vines store sugar in grapes through photosynthesis, and acids break down as grapes ripen. Secondary compounds are also stored in the course of the season. Anthocyanins give grapes a red color and protection against ultraviolet light. Tannins add bitterness and astringency which acts to defend vines against pests and grazing animals. Environmental factors such as soil, rainfall and fog affect flavor in ways that can be described collectively as "character" or the French term “ terroir”. As climate change disrupts long-established patterns of temperature and precipitation in wine-growing regions and causes more extreme weather events, the rate at which sugars, acids and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylphenol
Ethylphenol may refer to: * 2-Ethylphenol * 3-Ethylphenol * 4-Ethylphenol * Ethyl phenyl ether Ethyl phenyl ether (or phenetole) is an organic compound that belongs to a class of compounds called ethers. Ethyl phenyl ether has the same properties as some other ethers, such as volatility, explosive vapors, and the ability to form peroxides. ... (''O''-ethylphenol) {{Short pages monitor ... [...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] |
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 major factors in different styles of wine. These differences result from the complex interactions between the biochemical development of the grape, the reactions involved in fermentation, the grape's growing environment (terroir), and the wine production process. Many countries enact legal appellations intended to define styles and qualities of wine. These typically restrict the geographical origin and permitted varieties of grapes, as well as other aspects of wine production. Wines not made from grapes involve fermentation of other crops including rice wine and other fruit wines such as plum, cherry, pomegranate, currant and elderberry. Wine has been produced for thousands of years. The earliest evidence of wine is from the Caucasus ... [...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] |
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] |
