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Acetoin
Acetoin, also known as 3-hydroxybutanone or acetyl methyl carbinol, is an organic compound with the formula CH3CH(OH)C(O)CH3. It is a colorless liquid with a pleasant, buttery odor. It is chiral. The form produced by bacteria is (''R'')-acetoin.Albert Gossauer: ''Struktur und Reaktivität der Biomoleküle'', Verlag Helvetica Chimica Acta, Zürich, 2006, Seite 285, . Production in bacteria Acetoin is a neutral, four-carbon molecule used as an external energy store by a number of fermentative bacteria. It is produced by the decarboxylation of alpha- acetolactate, a common precursor in the biosynthesis of branched-chain amino acids. Owing to its neutral nature, production and excretion of acetoin during exponential growth prevents over-acidification of the cytoplasm and the surrounding medium that would result from accumulation of acidic metabolic products, such as acetic acid and citric acid. Once superior carbon sources are exhausted, and the culture enters stationary phase, ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetoin Dehydrogenase
Acetoin dehydrogenase (, ''acetoin dehydrogenase complex'', ''acetoin dehydrogenase enzyme system'', ''AoDH ES'') is an enzyme with List of enzymes, systematic name ''acetyl-CoA:acetoin O-acetyltransferase''. This enzyme catalysis, catalyses the following chemical reaction : acetoin + CoA + NAD+ \rightleftharpoons acetaldehyde + acetyl-CoA + NADH + H+ This enzyme requires thiamine diphosphate. See also * Diacetyl reductase References External links * {{Portal bar, Biology, border=no EC 2.3.1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
(R,R)-butanediol Dehydrogenase
In enzymology, a (R,R)-butanediol dehydrogenase () is an enzyme that catalyzes the chemical reaction :(R,R)-butane-2,3-diol + NAD \rightleftharpoons (R)-acetoin + NADH + H Thus, the two substrates of this enzyme are (R,R)-butane-2,3-diol and NAD, whereas its 3 products are (R)-acetoin, NADH, and H. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD or NADP as acceptor. The systematic name of this enzyme class is (R,R)-butane-2,3-diol:NAD oxidoreductase. Other names in common use include butyleneglycol dehydrogenase, D-butanediol dehydrogenase, D-(−)-butanediol dehydrogenase, butylene glycol dehydrogenase, diacetyl (acetoin) reductase, D-aminopropanol dehydrogenase, D-aminopropanol dehydrogenase, 1-amino-2-propanol dehydrogenase, 2,3-butanediol dehydrogenase, D-1-amino-2-propanol dehydrogenase, (R)-diacetyl reductase, (R)-2,3-butanediol dehydrogenase, D-1-amino-2-propanol:NAD oxidoreductase, 1-amino-2-propanol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diacetyl
Diacetyl ( ; IUPAC systematic name: butanedione or butane-2,3-dione) is an organic compound with the chemical formula (CH3CO)2. It is a yellow liquid with an intensely buttery flavor. It is a vicinal diketone (two C=O groups, side-by-side). Diacetyl occurs naturally in alcoholic beverages and some cheeses and is added as a flavoring to some foods to impart its buttery flavor. Chronic inhalation exposure to diacetyl fumes is a causative agent of the lung disease bronchiolitis obliterans, commonly known as " popcorn lung". Chemical structure A distinctive feature of diacetyl (and other vicinal diketones) is the long C–C bond linking the carbonyl centers. This bond distance is about 1.54 Å, compared to 1.45 Å for the corresponding C–C bond in 1,3-butadiene. The elongation is attributed to repulsion between the polarized carbonyl carbon centers. Occurrence and biosynthesis Diacetyl arises naturally as a byproduct of fermentation. In some fermentative bacteria, it i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Artificial Butter Flavor
Artificial butter flavoring is a flavoring used to give a food the taste and smell of butter. It may contain diacetyl, acetylpropionyl, or acetoin, three natural compounds in butter that contribute to its characteristic taste and smell. Manufacturers of margarines or similar oil-based products typically add it (along with beta carotene for the yellow color) to make the final product butter-flavored, because it would otherwise be relatively tasteless. Butter-flavoring controversy The lung disease bronchiolitis obliterans is attributed to prolonged exposure to diacetyl, e.g. in an industrial setting. Workers in several factories that manufacture artificial butter flavoring have been diagnosed with bronchiolitis obliterans, a rare and serious disease of the lungs. The disease has been called "popcorn worker's lung" or "popcorn lung" because it was first seen in former workers of a microwave popcorn factory in Missouri, but NIOSH refers to it by the more general term "flavorings-r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flavoring
A flavoring (or flavouring), also known as flavor (or flavour) or flavorant, is a food additive that is used to improve the taste or smell of food. It changes the perceptual impression of food as determined primarily by the chemoreceptors of the gustatory and olfactory systems. Along with additives, other components like sugars determine the taste of food. A flavoring is defined as a substance that gives another substance taste, altering the characteristics of the solute, causing it to become sweet, sour, tangy, etc. Although the term, in common language, denotes the combined chemical sensations of taste and smell, the same term is used in the fragrance and flavors industry to refer to edible chemicals and extracts that alter the flavor of food and food products through the sense of smell. Owing to the high cost, or unavailability of natural flavor extracts, most commercial flavorings are "nature-identical", which means that they are the chemical equivalent of natural ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voges–Proskauer Test
Voges–Proskauer or VP is a test used to detect acetoin in a bacterial broth culture. The test is performed by adding alpha-naphthol and potassium hydroxide to the Voges-Proskauer broth, which is a glucose-phosphate broth that has been inoculated with bacteria. A cherry red color indicates a positive result, while a yellow-brown color indicates a negative result. The test depends on the digestion of glucose to acetylmethylcarbinol. In the presence of oxygen and strong base, the acetylmethylcarbinol is oxidized to diacetyl, which then reacts with guanidine compounds commonly found in the peptone medium of the broth. Alpha-naphthol acts as a color enhancer, but the color change to red can occur without it. Procedure: First, add the alpha-naphthol; then, add the potassium hydroxide. A reversal in the order of the reagents being added may result in a weak-positive or false-negative reaction. VP is one of the four tests of the IMViC series, which tests for evidence of an ente ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetolactate
α-Acetolactic acid is a precursor in the biosynthesis of the branched chain amino acids valine and leucine. α-Acetolactic acid is produced from two molecules of pyruvic acid by acetolactate synthase. α-Acetolactic acid can also be decarboxylated by alpha- acetolactate decarboxylase to produce acetoin. The name α-acetolactate is used for anion (conjugate base), salts, and ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...s of α-acetolactic acid. References {{Reflist Alpha hydroxy acids Beta-keto acids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetyl-CoA
Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidation, oxidized for energy production. Coenzyme A (CoASH or CoA) consists of a cysteamine, β-mercaptoethylamine group linked to pantothenic acid (vitamin B5) through an amide linkage and 3'-phosphorylated ADP. The acetyl group (indicated in blue in the structural diagram on the right) of acetyl-CoA is linked to the sulfhydryl substituent of the β-mercaptoethylamine group. This thioester linkage is a "high energy" bond, which is particularly reactive. Hydrolysis of the thioester bond is exergonic (−31.5 kJ/mol). CoA is acetylated to acetyl-CoA by the breakdown of carbohydrates through glycolysis and by the breakdown of fatty acids through Beta oxidation, β-oxidation. Acetyl-CoA then enters the citric acid cycle, where the acetyl group is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vegetable Fats And Oils
Vegetable oils, or vegetable fats, are oils extracted from seeds or from other parts of edible plants. Like animal fats, vegetable fats are ''mixtures'' of triglycerides. Soybean oil, grape seed oil, and cocoa butter are examples of seed oils, or fats from seeds. Olive oil, palm oil, and rice bran oil are examples of fats from other parts of plants. In common usage, vegetable ''oil'' may refer exclusively to vegetable fats which are liquid at room temperature. Vegetable oils are usually edible. History In antiquity Olive oil has been a part of human culture for millennia.Ruth Schuster (December 17, 2014). "8,000-year old olive oil found in Galilee, earliest known in world", ''Haaretz''. Retrieved December 17, 2014. Archaeological evidence shows that olives were turned into olive oil by 6000 BC and 4500 BC in present-day Israel. Pagnol, p. 19, says the 6th millennium in Jericho, but cites no source. In ancient Egypt, plant oils including cedar oil, cypress oil, and ol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogenation
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to redox, reduce or Saturated and unsaturated compounds, saturate organic compounds. Hydrogenation typically constitutes the addition of pairs of hydrogen atoms to a molecule, often an alkene. Catalysts are required for the reaction to be usable; non-catalytic hydrogenation takes place only at very high temperatures. Hydrogenation reduces Double bond, double and Triple bond, triple bonds in hydrocarbons. Process Hydrogenation has three components, the Saturated and unsaturated compounds, unsaturated substrate, the hydrogen (or hydrogen source) and, invariably, a catalyst. The redox, reduction reaction is carried out at different temperatures and pressures depending upon the substrate and the activity of the catalyst. Related or competing reactions The same cataly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Butter
Butter is a dairy product made from the fat and protein components of Churning (butter), churned cream. It is a semi-solid emulsion at room temperature, consisting of approximately 81% butterfat. It is used at room temperature as a spread (food), spread, melted as a condiment, and used as a Cooking fat, fat in baking, sauce-making, pan frying, and other cooking procedures. Most frequently made from cow's milk, butter can also be manufactured from the milk of other mammals, including Sheep milk, sheep, Goat milk, goats, Buffalo milk, buffalo, and Yak milk, yaks. It is made by churning milk or cream to separate the fat globules from the buttermilk. Dairy salt, Salt has been added to butter since antiquity to help Food preservation, preserve it, particularly when being transported; salt may still play a preservation role but is less important today as the entire supply chain is usually refrigerated. In modern times, salt may be added for taste and food coloring added for color. Kit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2,3-butanediol
2,3-Butanediol is the organic compound with the formula (CH3CHOH)2. It is classified as a ''vic''-diol (glycol). It exists as three stereoisomers, a chiral pair and the meso isomer. All are colorless liquids. Applications include precursors to various plastics and pesticides. Isomerism Of the three stereoisomers, two are enantiomers (levo- and dextro-2,3-butanediol) and one is a meso compound. The enantiomeric pair have (2''R'', 3''R'') and (2''S'', 3''S'') configurations at carbons 2 and 3, while the meso compound has configuration (2''R'', 3''S'') or, equivalently, (2''S'', 3''R''). Industrial production and uses 2,3-Butanediol is prepared by hydrolysis of 2,3-epoxybutane:Heinz Gräfje, Wolfgang Körnig, Hans-Martin Weitz, Wolfgang Reiß, Guido Steffan, Herbert Diehl, Horst Bosche, Kurt Schneider and Heinz Kieczka "Butanediols, Butenediol, and Butynediol" in ''Ullmann's Encyclopedia of Industrial Chemistry'', 2000, Wiley-VCH, Weinheim. :(CH3CH)2O + H2O → CH3(CHOH) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
