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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 seconda ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monoterpene
Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen functionality or missing a methyl group, are called monoterpenoids. Monoterpenes and monoterpenoids are diverse. They have relevance to the pharmaceutical, cosmetic, agricultural, and food industries. Biosynthesis Monoterpenes are derived biosynthetically from units of isopentenyl pyrophosphate, which is formed from acetyl-CoA via the intermediacy of mevalonic acid in the HMG-CoA reductase pathway. An alternative, unrelated biosynthesis pathway of IPP is known in some bacterial groups and the plastids of plants, the so-called MEP-(2-methyl-D-erythritol-4-phosphate) pathway, which is initiated from C5 sugars. In both pathways, IPP is isomerized to DMAPP by the enzyme isopentenyl pyrophosphate isomerase. Geranyl pyrophosphate is the precu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gum Arabic
Gum arabic, also known as gum sudani, acacia gum, Arabic gum, gum acacia, acacia, Senegal gum, Indian gum, and by other names, is a natural gum originally consisting of the hardened sap of two species of the ''Acacia'' tree, '' Senegalia senegal'' and '' Vachellia seyal.'' The term "gum arabic" does not legally indicate a particular botanical source, however. The gum is harvested commercially from wild trees, mostly in Sudan (80%) and throughout the Sahel, from Senegal to Somalia. The name "gum Arabic" (''al-samgh al-'arabi'') was used in the Middle East at least as early as the 9th century. Gum arabic first found its way to Europe via Arabic ports, so retained its name. Gum arabic is a complex mixture of glycoproteins and polysaccharides, predominantly polymers of arabinose and galactose. It is soluble in water, edible, and used primarily in the food industry and soft-drink industry as a stabilizer, with E number E414 (I414 in the US). Gum arabic is a key ingredient in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur Dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activity and is produced as a by-product of copper extraction and the burning of sulfur- bearing fossil fuels. Structure and bonding SO2 is a bent molecule with ''C''2v symmetry point group. A valence bond theory approach considering just ''s'' and ''p'' orbitals would describe the bonding in terms of resonance between two resonance structures. The sulfur–oxygen bond has a bond order of 1.5. There is support for this simple approach that does not invoke ''d'' orbital participation. In terms of electron-counting formalism, the sulfur atom has an oxidation state of +4 and a formal charge of +1. Occurrence Sulfur dioxide is found on Earth and exists in very small concentrations and in the atmosphere at about 1 ppm. On other p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ascorbic Acid
Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) and wrinkles on the face. It is used to prevent and treat scurvy. Vitamin C is an essential nutrient involved in the repair of tissue, the formation of collagen, and the enzymatic production of certain neurotransmitters. It is required for the functioning of several enzymes and is important for immune system function. It also functions as an antioxidant. Most animals are able to synthesize their own vitamin C. However, apes (including humans) and monkeys (but not all primates), most bats, some rodents, and certain other animals must acquire it from dietary sources. There is some evidence that regular use of supplements may reduce the duration of the common cold, but it does not appear to prevent infection. It is unclear whether s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycosidase
Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes with roles in nature including degradation of biomass such as cellulose (cellulase), hemicellulose, and starch (amylase), in anti-bacterial defense strategies (e.g., lysozyme), in pathogenesis mechanisms (e.g., viral neuraminidases) and in normal cellular function (e.g., trimming mannosidases involved in N-linked glycoprotein biosynthesis). Together with glycosyltransferases, glycosidases form the major catalytic machinery for the synthesis and breakage of glycosidic bonds. Occurrence and importance Glycoside hydrolases are found in essentially all domains of life. In prokaryotes, they are found both as intracellular and extracellular enzymes that are largely involved in nutrient acquisition. One of the important occurrences of glycoside hydrolases in bacteria is the enzyme beta-galactosidase (LacZ), wh ... [...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 reg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitis Vinifera
''Vitis vinifera'', the common grape vine, is a species of flowering plant, native to the Mediterranean region, Central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern Iran. There are currently between 5,000 and 10,000 varieties of ''Vitis vinifera'' grapes though only a few are of commercial significance for wine and table grape production. The wild grape is often classified as ''Vitis vinifera'' ''sylvestris'' (in some classifications considered ''Vitis sylvestris''), with ''Vitis vinifera'' ''vinifera'' restricted to cultivated forms. Domesticated vines have hermaphrodite flowers, but ''sylvestris'' is dioecious ( male and female flowers on separate plants) and pollination is required for fruit to develop. Grapes can be eaten fresh or dried to produce raisins, sultanas, and currants. Grape leaves are used in the cuisine of many cultures. The fresh grapes can also be processed into juice that is fermented to make ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norisoprenoid
Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes are further classified by the number of carbons: monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), as examples. The terpene alpha-pinene, is a major component of the common solvent, turpentine. History and terminology The term ''terpene'' was coined in 1866 by the German chemist August Kekulé to denote all hydrocarbons having the empirical formula C10H16, of which camphene was one. Previously, many hydrocarbons having the empirical formula C10H16 had been called "camphene", but many other hydrocarbons of the same composition had had different names. Kekulé coined the term "terpene" in order to reduce the confusion. The name "terpene" is a shortened form of "terpentine", an obsolete spelling of "turpentine". Although sometime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethyl Acetate
Ethyl acetate ( systematically ethyl ethanoate, commonly abbreviated EtOAc, ETAC or EA) is the organic compound with the formula , simplified to . This colorless liquid has a characteristic sweet smell (similar to pear drops) and is used in glues, nail polish removers, and in the decaffeination process of tea and coffee. Ethyl acetate is the ester of ethanol and acetic acid; it is manufactured on a large scale for use as a solvent. Production and synthesis Ethyl acetate was first synthesized by the Count de Lauraguais in 1759 by distilling a mixture of ethanol and acetic acid. In 2004, an estimated 1.3 million tonnes were produced worldwide. The combined annual production in 1985 of Japan, North America, and Europe was about 400,000 tonnes. The global ethyl acetate market was valued at $3.3 billion in 2018. Ethyl acetate is synthesized in industry mainly via the classic Fischer esterification reaction of ethanol and acetic acid. This mixture converts to the ester in ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methoxypyrazines
Methoxypyrazines are a class of chemical compounds that produce odors. The odors tend to be undesirable, as in the case of certain wines, or as defensive chemicals used by insects such as ''Harmonia axyridis'' which produces isopropyl methoxy pyrazine (IPMP). They have also been identified as additives in cigarette manufacture. Detection thresholds are very low, typically near 2 parts per trillion (1 ng/L). Examples of methoxypyrazines in wine grapes Cabernet Sauvignon has high levels of methoxypyrazines.Oz Clarke ''Encyclopedia of Grapes'' pg 223 Harcourt Books 2001 Two methoxypyrazine compounds, 3-isobutyl-2-methoxypyrazine (IBMP) and 3-isopropyl-2-methoxypyrazine (IPMP), are considered to be important determinants of green flavours in Sauvignon blanc wines.Marais, J., Hunter, J.J., & Haasbroek, P.D. (1999). Effect of microclimate, season and region on Sauvignon blanc grape composition and wine quality. South African Journal of Enology and Viticulture, 20, 19-30. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glutathione
Glutathione (GSH, ) is an antioxidant in plants, animals, fungi, and some bacteria and archaea. Glutathione is capable of preventing damage to important cellular components caused by sources such as reactive oxygen species, free radicals, peroxides, lipid peroxides, and heavy metals. It is a tripeptide with a gamma peptide linkage between the carboxyl group of the glutamate side chain and cysteine. The carboxyl group of the cysteine residue is attached by normal peptide linkage to glycine. Biosynthesis and occurrence Glutathione biosynthesis involves two adenosine triphosphate-dependent steps: *First, γ-glutamylcysteine is synthesized from L-glutamate and cysteine. This conversion requires the enzyme glutamate–cysteine ligase (GCL, glutamate cysteine synthase). This reaction is the rate-limiting step in glutathione synthesis. *Second, glycine is added to the C-terminal of γ-glutamylcysteine. This condensation is catalyzed by glutathione synthetase. While all ani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
