Definition of carbohydrates

The term carbohydrate arose because most sugars have molecular formulas Cffi(H20),n, suggesting that carbon atoms are combined in some way with water. In fact, the empirical formula of most simple sugars is C(H20). Chemists named these compounds hydrates of carbon or carbohydrates because of these molecular formulas. Our modern definition of carbohydrates includes polyhydroxyaldehydes, poly-hydroxyketones, and compounds that are easily hydrolyzed to them. 

The common definition of carbohydrates is polyhydroxy aldehydes or ketones (the carbonyl group is generally at C-2), their derivatives, oligomers and polymers. The term itself arises from the empirical formula of the compounds initially studied (glucose, for example) since that is represented by C(H20) . 

By far the majority of carbohydrate material in nature occurs in the form of polysaccharides. By our definition, polysaccharides include not only those substances composed only of glycosidically linked sugar residues but also molecules that contain polymeric saccharide structures linked via covalent bonds to amino acids, peptides, proteins, lipids, and other structures. 

Carb-O. Historical development of carbohydrate nomenclature 0.1. Early approaches 0.2. The contribution of Emil Fischer 0.3. Cyclic forms 0.4. Nomenclature commissions 2-Carb-l. Definitions and conventions... 

The present Recommendations deal with the acyclic and cyclic forms of monosaccharides and their simple derivatives, as well as with the nomenclature of oligosaccharides and polysaccharides. They are additional to the Definitive Rules for the Nomenclature of Organic Chemistry [13,14] and are intended to govern those aspects of the nomenclature of carbohydrates not covered by those rules. 

Since the early 1970s a panel convened by the International Union of Pure and Applied Chemistry and the International Union of Biochemistry and Molecular Biology has been working to formulate recommendations for carbohydrate nomenclature that meet developing needs of research and electronic data handling, while retaining links to the established literature base on carbohydrates. The realization of these endeavors is presented here in the final document Nomenclature of Carbohydrates, which provides a definitive reference for current researchers, both in the text version and in the version accessible on the World Wide Web (http //www.chem.qmw.ac.uk/iupac/2carb/), where amendments and revisions are maintained. 

The regulations prescribe the energy values to be used as in Table 3. There are agreed values for some other materials. The synthetic dextrose polymer poly dextrose is accepted to be only 1 kcal g 1 (or 4 kJ g 1) even though it would otherwise fall within the definition of a carbohydrate. The accepted value for gum acacia, a polysaccharide obtained from trees of the species Acacia Senegal and closely related species, is 2 kcal g 1 (or 8 kJ g-1). 

Average dissolved fractions of carbohydrates and proteins are shown in Table 3.4. Protein only exists in a dissolved form after transport in a sewer network, whereas lipids, per definition, are nondissolved. 

Alcohol consumption is very difficult to assess. There is widespread belief that individuals underreport their intake and there are no reliable laboratory tests available for definitive diagnosis of alcohol abuse. A combination of abnormalities in the plasma activity of gamma-glutamyl transferase (GGT or yGT), AST and reduction in erythrocyte mean cell volume (MCV) maybe useful and all are routine lab. tests. A potential marker of interest is carbohydrate-deficient transferrin (CDT) which is an abnormal isoform of serum transferrin arising due to defects in the attachment of carbohydrate chains to the protein core. Unfortunately, CDT is a somewhat specialized test, not performed by most laboratories. Other markers which have attracted some research interest are ethyl sulphate and ethyl glucuronide. Excretion in the urine of these metabolites occurs for up to 50 hours after binge drinking so they offer a useful index of recent heavy alcohol intake. 

R. E. Ireland and J. P. Vevert, A chiral total synthesis of (—) and (+) nonactic acids from carbohydrate precursors and the definition of the transition for the enolate Claisen rearrangement in heterocyclic systems, J. Org. Chem. 45 4259 (1980). 

Substitute milk products may not be equivalent to cow s milk in terms of the quantity and in some cases the quality of fat, carbohydrate, vitamins, and minerals. Fat, carbohydrate, sodium, fiber, and energy, as well as the nutrients for which no U.S. RDA has been established, were not considered by FDA in its proposed definition of nutritional equivalency. In terms of quality, coconut oil, the primary and in most instances the sole fat used in substitute as well as imitation milk products, is a more saturated fat than milk fat and lacks linoleic acid, an essential fatty acid. Thus, a substitute dairy product formulated with hydrogenated coconut oil and sucrose and containing more so-... 

In this biographical notice, we shall maintain, in English translation, some of the nomenclature employed by Emil Fischer. The names used by Fischer sufficed to meet the needs of the structures as then known, and have served as a solid basis for modem carbohydrate nomenclature, which, however, requires the definition of structural features unknown to Fischer. 

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