Sweeteners fructose

Another name for glucitol obtained by reduction of d glucose is sorbitol it is used as a sweetener especially in special diets required to be low in sugar Reduction of D fructose yields a mixture of glucitol and mannitol corresponding to the two possi ble configurations at the newly generated chirality center at C 2... 

Fructose—Dextrose Separation. Emctose—dextrose separation is an example of the appHcation of adsorption to nonhydrocarbon systems. An aqueous solution of the isomeric monosaccharide sugars, C H 2Dg, fmctose and dextrose (glucose), accompanied by minor quantities of polysaccharides, is produced commercially under the designation of "high" fmctose com symp by the enzymatic conversion of cornstarch. Because fmctose has about double the sweetness index of dextrose, the separation of fmctose from this mixture and the recycling of dextrose for further enzymatic conversion to fmctose is of commercial interest (see Sugar Sweeteners). 

Early applications of crystalline fructose focused on foods for special dietary applications, primarily calorie reduction and diabetes control. The latter application sought to capitalize on a signiftcandy lower serum glucose level and insulin response in subjects with noninsulin-dependent diabetes melUtus (21,22) and insulin-dependent diabetes (23). However, because fmctose is a nutritive sweetener and because dietary fmctose conversion to glucose in the hver requires insulin in the same way as dietary glucose or sucrose, recommendations for its use are the same as for other nutritive sugars (24). Review of the health effects of dietary fmctose is available (25). 

In 1993, the di-D-fructose dianhydrides were summarized as being of little, if any, commercial importance. 73 However, a search of the literature reveals an appreciable number of patents issued since 1989 for the manufacture of these compounds. These include enzymic methods for the production of individual dianhydrides (Ref. 130) or methods of production of mixtures using anhydrous HF or pyridinium poly(hydrogen fluoride) (see Ref. 131). Most cite the di-D-fructose dianhydrides as low-calorie sweetening agents (Ref. 132), and some claim anti-cariogenic properties (Refs. 132 and 133). 

High fructose corn syrups (HFCS), 10 253, 290 23 484 26 288-289 High fructose corn sweetener (HFCS),... 

Fructose has a much sweeter taste than glucose, hence the transformation of glucose derived from enzymatic hydrolysis of starch from com, provides an alternative sweetener to sucrose (a disaccharide of glucose and fructose). This replaced the use of sugar cane by the US soft drinks and candy industry (and effectively destroyed the economy of Cuba in the process). 

The substantial amounts of this ketohexose are mainly prepared by base-catalyzed isomerization of starch-derived glucose, yet may also are generated by hydrolysis of inulin, a fructooligosaccharide. An aqueous solution of fructose—consisting of a mixture of all four cyclic tautomers (Figure 2.5), of which only the (3-D-pyranose ((3-p) form present to about 73% at room temperature is sweet — about 1.5 times sweeter than an equimolar solution of sucrose hence, it is widely used as a sweetener for beverages ( high fructose syrup ). 

Like D-glucose and D-fructose, however, D-xylose can be utilized chemic ly or microbially—to generate a variety of interesting five-ca n c emica s o er than furfural (vide supra) or xylitol, a noncaloric sweetener, both being duectly produced from xylan hydrolysates, that is, without the actual isolation of the sugar. Other readily accessible intermediate products of high preparative utiUty (Scheme 2.14) are the open-chain fixed dithioacetal, the D-xylal, and D-hydroxy-xylal esters, or pyrazol or imidazol A -heterocycles with a hydrophilic trihydroxypropyl side chain. 

On Ca +-form columns, some separation of monosaccharides is possible and, for the separation of galactose and glucose in dairy products, this is the column of choice. The separation of several disaccharides, such as sucrose plus maltose plus lactose, in sweetened dairy products cannot be accomplished on single-resin columns, however, and separation on amine-modified silica gel or on dual-resin columns " is recommended. These columns are capable of separating the five major food sugars, namely, D-glucose, D-fructose, sucrose, maltose, and lactose, but are subject to rapid degradation if proper precautions are not used (see Section II,2,a). 

The high sweetness of fructose combined with that of glucose means invert sugar is sweeter than sucrose, so it provides a cheaper, less calorific sweetener than sucrose. The relative sweetness figures for sucrose, glucose and fructose are 1.0, 0.7 and 1.7 respectively. Honey is also composed mainly of invert sugar. 

On the other hand, borohydride reduction of the ketose o-fructose will give a mixture of o-glucitol and its epimer, D-mannitol. A better approach to D-mannitol would be reduction of the aldose D-mannose. o-Glucitol (sorbitol) is found naturally in the ripe berries of the mountain ash (Sorbus aucuparia), but is prepared semi-synthetically from glucose. It is half as sweet as sucrose, is not absorbed orally, and is not readily metabolized in the body. It finds particular use as a sweetener for diabetic products. o-Mannitol also occurs naturally in manna, the exudate of the manna ash Fraxinus ornus. This material has similar characteristics to sorbitol, but is used principally as a diuretic. It is injected intravenously, is eliminated rapidly into the urine, and removes fluid by an osmotic effect. 

High fructose corn syrup (MFCS) has emerged In recent years as an alternative nutritional sweetener to sucrose. However, the use of HFCS has been confined to those applications suited to liquid syrups, In particular the beverage and canning sectors of the market. The manufacture of fructose as a crystalline product would open up further market opportunities for the sweetener. One company In the USA Is producing crystalline fructose In commodity quantities (1), but at a higher price than sucrose. 

Rare or unnatural monosaccharides have many useful applications as nonnutritive sweeteners, glycosidase inhibitors and so on. For example, L-glucose and L-fructose are known to be low-calorie sweeteners. In addition, rare or unnatural monosaccharides are potentially useful as chiral building blocks for the synthesis of biologically active compounds. Therefore, these compounds have been important targets for the development of enzymatic synthesis based in the use of DHAP-dependent aldolases alone or in combination with isomerases. Fessner et al. showed that rare ketose-1-phosphates could be reached not only by aldol addition catalyzed by DHAP-dependent aldolases, but by enzymatic isomerization/ phosphorylation of aldoses [35]. Thus, for example, L-fructose can be prepared... 

Hereditary fructose intolerance is due to aldolase B deficiency and is often diagnosed when babies are switched from formula or mother s milk to a diet containing fructose-based sweetening, such as sucrose or honey. 

In the production of the sweetener high fructose com symp (HFCS), glucose isomerase is used to convert glucose into fmctose (equilibrium mixture appr. 50 50) since fmctose is nearly three times as sweet as glucose. The enzyme belongs to the subclass intramolecular oxidoreductases interconverting aldoses and ketoses (EC 5.3.1). About 8 million tonnes pr. year of glucose is treated in this way. For further details, see Chapter 4. 

Fructose, another common monosaccharide found in fruits and honey, is more soluble in water than glucose and is also sweeter than glucose. It is used as a sweetener for diabetic patients, and in infusion for parenteral nutrition. 

Fructose is sweeter than sucrose at low temperatures ( 5° C) at higher temperatures, the reverse is true. At 40°C, they have equal sweetness, the result of a temperature-induced shift in the percentages of a- and p-fructose anomers. The taste of sucrose is syneigistic with high intensity sweeteners (eg, sucralose and aspartame) and can be enhanced or prolonged by substances like glycerol monostearate, lecithin, and maltol (19). 

Sucrose occupies a unique position in the sweetener market (Table 3). The total market share of sucrose as a sweetener is 85%, compared to other sweeteners such as high fructose com syrup (HFCS) at 7%, alditols at 4%, and synthetic sweeteners (aspartame, acesulfame-K, saccharin, and cyclamate) at 4%. The world consumption of sugar has kept pace with the production. The rapid rise in the synthetic sweetener market during 1975—1995 appears to have reached a maximum. 

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