Carbohydrates/sugar fructose

The melting points of carbohydrates (sugars) are not usually sharp and they are perhaps best expressed as decomposition points, t The small capital letter prefix refers to configuration, relat to D- lyceraldehyde, and not to the direction of optical rotation. The sign of optical rotation is expressed as (+) and (—) or as d and I or by the words dtxtro and loevo. Thus we have d-(—)-fructose and ,-(+).arabinose. 

The food fiavorist also must be aware of metal complexes, which carbohydrates are capable of forming, Iron salts not only form complexes with dietary fiber, but with nearly all of the known natural sugars. Fructose, maltitol. sorbitol, and xylitol can easily form complexes with the ferric... 

The aldehyde and ketone units appear in some biologically important systems. The ketone unit appears in many carbohydrates (sugars), including ribulose (85), fructose (86), and sorbose (87). d-Ribulose is an intermediate in the fungal pathway for d-arabitol production as the l,5-6is(phosphate), d-ribulose combines with carbon dioxide at the start of the photosynthetic process in green... 

The materials used for ORT are simple mixtures of water, salts, and carbohydrates. These materials are regulated by the FDA as a medical food and are available in most grocery and drug stores. A list of ingredients from the label of the liquid form of a popular ORT product includes water the two carbohydrate sugars dextrose and fructose citric acid and the salts potassium citrate, sodium citrate, and sodium chloride. This material is available in an unflavored form and in several flavors, such as berry and bubblegum, to appeal to children. The product also comes in the form of a powder that has to be dissolved in water before use. A third form consists of liquid... 

Molisch s test A general test for carbohydrates. The carbohydrate is dissolved in water, alcoholic 1-naphthol added, and concentrated sulphuric acid poured down the side of the tube. A deep violet ring is formed at the junction of the liquids. A modification, the rapid furfural test , is used to distinguish between glucose and fructose. A mixture of the sugar, 1-naphthol, and concentrated hydrochloric acid is boiled. With fructose and saccharides containing fructose a violet colour is produced immediately the solution boils. With glucose the appearance of the colour is slower. 

The most familiar of all the carbohydrates is sucrose—common table sugar. Sucrose is a disacchar ide in which D-glucose and D-fructose are joined at then anomeric carbons by a glycosidic bond (Figure 25.7). Its chemical composition is the same ine-spective of its source sucrose from cane and sucrose from sugar beets are chemically identical. Because sucrose does not have a free anomeric hydroxyl group, it does not undergo mutarotation. 

Combined electrolyte solutions are available for oral and IV administration. The IV solutions contain various electrolytes and dextrose. The amount of electrolytes, given as milliequivalents per liter (mEq/L), also varies. The IV solutions are used to replace fluid and electrolytes that have been lost and to provide calories by means of their carbohydrate content. Examples of IV electrolyte solutions are dextrose 5% with 0.9% NaCl, lactated Ringer s injection, Plasma-Lyte, and 10% Travert (invert sugar—a combination of equal parts of fructose and dextrose) and Electrolyte No. 2. 

D-Fructose is the sweetest sugar known in naturally occurring carbohydrates, and its intense sweetness is produced only by ) -D-fructopyranose. "... 

Cellulose and starch are macromolecules with empirical formulas that resemble hydrated carbon, CX (H2 0)y, where x and y are integers. The monomers from which these macromolecules are consfructed are sugars such as glucose and fructose. These monomers and macromolecules are the carbohydrates. Structurally, carbohydrates are very different from simple combinations of carbon and water. Even the smallest carbohydrates contain carbon chains with hydrogen atoms, OH groups, and occasional ether linkages. 

HMF is an important versatile sugar derivative and is a key intermediate between bio-based carbohydrate chemistry and petroleum based industrial organic chemistry (1, 2). The most coimnon feedstock for HMF is fructose and reactions are carried out in water-based solvent systems using acid catalysis (3,4). HMF is unstable in water at low pH and breaks down to form levulinic acid and formic acid, resulting in an expensive HMF recovery process. In strongly polar organic co-solvents, such as dimethylsulfoxide (DMSO), levuhnic acid formation is reduced and HMF yields are improved (5). 

Carbohydrates are classified based upon the products formed when they are hydrolyzed. Monosaccharides are simple sugars that cannot be broken down into simpler sugars upon hydrolysis. Examples of monosaccharides are glucose, ribose, deoxyribose, and fructose. Disaccharides contain two monosaccharide units and yield two monosaccharides upon hydrolysis. Examples of disaccharides are lactose, maltose, and sucrose. Polysaccharides are polymers of monosaccharide units and yield many individual monosaccharides upon hydrolysis. Examples of polysaccharides are starch, glycogen, and cellulose. 

---