Sucrose natural sources

Sucrose is the most abundant disaccharide isolated from natural sources. All aspects of its chemistry were recently comprehensively reviewed.77 In this paper the new applications of sucrose as synthons in the preparation of fine chemicals will be reported. 

Fig. 25.1 The three pathways for the preparation of natural flavours. The first two involve the extraction of the flavour or precursors from natural sources. The precursors can then be converted to the natural flavour by enzymes extracted from plants or microorganisms. The last method is the de novo synthesis of the flavour by microorganisms growing on simple substrates such as glucose and sucrose...

Monosaccharides (e.g., glucose), disaccharides (e.g., sucrose), and oligosaccharides can be obtained readily from natural sources, either directly or by hydrolysis of natural carbohydrate polymers. These can be used to either modify synthetic adhesive resins or to replace them altogether. In addition, reactive derivatives could be synthesized from these compounds and used to formulate adhesive polymers. 

Several solid polyols can be used as direct compression diluents, usually after some physical modification. Most such polyols can be obtained from natural sources, but are usually manufactured by hydrogenation of the parent sugar molecule. Some properties of polyols, together with comparative data for lactose and sucrose, are shown in Table 6. 

MBR have also found use in the production of polysaccharides. MBR provide a simplified method for producing these materials, which are, typically, obtained in small quantities from natural sources by elaborate procedures. Hicke et al. [4.64] reported the synthesis of inulin (poly-j8-(2,l)-frutan) in a MBR with the aid of fructosyltransferase immobilized in the membrane s porous structure. Inulin, with a high molecular weight and low polydispersity, was continuously synthesized from sucrose, as the substrate passed through the MF membrane. 

Draw the structures of sucrose, lactose, and maltose. Give the natural sources of these common disaccharides. 

Vibrio species are difficult to isolate from natural sources as they tend to be present with coliforms, which outgrow them on many media. Several selective media are available, including DCLS Agar which contains sodium desoxycholate, lactose, sucrose, and the indicator Neutral Red, the desoxycholate suppressing the growth of coliforms. Cholera medium works in a similar manner, in that high levels of ox bile are used to suppress the growth of the normal gut flora. 

State the natural sources of sucrose, maltose, lactose, and starch. 

In addition, sucrose is widely available in very large quantities, being obtained from ecologically attractive natural sources, sugar cane and sugar beets. Its price, in pure form, however, is relatively high and subject to rather severe fluctations due to environmental, economic and political influences. 

Description. The common aspect among the surfactants grouped in this class and the sorbitan esters and alkyl carbohydrates esters classes is that they all derive from the condensation reaction of a polyhydroxyl compound (glycol, glycerol, sorbitol, sucrose, etc.) with a fatty acid. Some of them can be directly extracted from natural sources. 

Isolation from Natural Sources.- The very bitter tasting constituents of certain stone-fruit have been shown to be l,6,2, 6 -tetra- and l,6,2, 4, 6 -penta-0-acetyl-3-0-coumaroyl-sucrose. Six derivatives of octyl 4-0-acetyl-a-a-L-rhamnopyranosyl-(l->3)-2,4-di-( -acetyl-a-L-rhamnopyranosyl-(l->3)-4-0-hexanoyl-a-L-rhamnopyranoside, extracted from the bark of Mezettia leptopoda, have been characterized by n.m.r. and m.s. methods. ... 

In more detail the nutrient medium used may contain sources of carbon such as starch, hydrolyzed starch, sugars such as lactose, maltose, dextrose, sucrose, or sugar sources such as molasses alcohols, such as glycerol and mannitol organic acids, such as citric acid and acetic acid and various natural products which may contain other nutrient materials in addition to carbonaceous substances. 

Extrafloral nectaries include a wide range of nectar-excreting structures, which are distinguished from their floral counterparts by the fact that they are not involved in pollination. Extrafloral nectar is typically dominated by sucrose and its hexose components glucose and fructose. The fact that these common sugars are acceptable to the majority of insects, combined with the exposed nature of extrafloral nectaries, makes them suitable food sources for abroad range of insects. Compared with floral nectar, extrafloral nectar often has increased fructose and glucose levels (Tanowitz... 

Xylitol is as sweet as sucrose and has been used as a food additive. Because it does not induce formation of dental plaque, it is used as a replacement for sucrose in chewing gum. It appeared to be an ideal sugar substitute for diabetics. However, despite the fact that it is already naturally present in the body, ingestion of large amounts of xylitol causes bladder tumors as well as oxalate stones in rats and mice. Its use has, therefore, been largely discontinued. A possible source of the problem may lie in the conversion by fructokinase of some of the xylitol to D-xylulose 1 -P, which can be cleaved by the xylulose 1-P aldolase to dihydroxy acetone P and glycolaldehyde. 

The second category of adulteration is by far the most common. For example, apple juice will normally contain around 11% by weight of solids. At least 90% of these solids are carbohydrates - sucrose, dextrose and fructose predominating. Considerably cheaper sources of carbohydrates can be found, and the simple addition of a mixture of carbohydrates in roughly the same proportion as those found naturally in apple juice can be used to stretch apple juice by a considerable proportion. In more sophisticated forms of adulteration the added components can be made to cany a similar signature to the juice. 

The procedure towards an environmentally benign process starts with the selection of raw materials in addition to conventional raw materials from the petrochemical industry based on low- to medium-boiling aliphatic and aromatic hydrocarbons, replenishable raw materials from nature are increasingly available nowadays. In the simplest cases, these can be carbon sources, such as glucose and sucrose for fermentation, but also more complex molecules, frequently obtained from the chiral pool or through inexpensive fermentation from carbon sources, such as glutamic acid or citric acid. Table 20.2 lists a selection of raw materials from the chiral pool, with their estimated costs per kilogram. 

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