5- , sucrose conversion

The telomerization of sucrose with butadiene was catalyzed in aqueous solution by palladium acetate and tppts (102). The sucrose conversion was about 96%, but octadienyl ethers of different degrees of alkylation were also formed. 

Pennequin et al. [89, 106] observed a much-improved selectivity towards the mono- and di-telomers by using the TPPTS ligand in an aqueous phase with added isopropanol and NaOH. At a Pd loading of 0.40 mol% (relative to sucrose) with TPPTS (P/Pd = 3), a sucrose conversion of 73% was observed after 30 min, with a selectivity of 66% to the mono-telomer and 32% to the di-telomer. The group of Pinel also used Pd/TPPTS for the telomerization with sucrose in water, obtaining differently substituted sucrose telomers depending on the chosen reaction parameters [ 107]. 

Forccd flow mode. Invertase, an enzyme, can be chemically immobilized to the surfaces of ceramic membrane pores by the technique of covalent bonding of silane-glutaraldehyde [Nakajima et al., 1989b]. The substrate (reactant), during the sucrose conversion process, enters the membrane reactor in a crossflow mode. Under suction from the other side of the membrane, the substrate flows into the enzyme-immobilized membrane pores where the bioconversion takes place. Both the product and the unreacted substrate indiscriminately pass through the membrane pores. Thus, no permselective properties are utilized in this case. The primary purpose of the membrane is to provide a well-engineered catalytic path for the reactant, sucrose. 

Krastanov A, Blazheva D, Stanchev V (2007), Sucrose conversion into palati-nose with immobilized Serratia plymuthica cells in a hoUow-flber bioreactor , Proc. Biochem., 42,1655-1659. 

The telomerization of sucrose has been studied more in depth. Using water alone as solvent, sucrose conversion was only 65% after 5 hours with 36% of mono and 48% of dioctadienyl compounds. The use of basic conditions (sodium hydroxide 1 M) resulted in a large increase of the catalytic activity for example, after only 26 minutes, 87% of sucrose was very selectively converted into octadienyl ethers with a higher average degree of substitution (DS = 2.4) (Scheme 11). Under these conditions, a turnover frequency of 5400 h could be observed after 20 min, at the maximum conversion rate. ... 

Reaction with Organic Compounds. Many organic reactions are catalyzed by acids such as HCl. Typical examples of the use of HCl in these processes include conversion of HgnoceUulose to hexose and pentose, sucrose to inverted sugar, esterification of aromatic acids, transformation of acetaminochlorobenzene to chloroaruHdes, and inversion of methone [1074-95-9]. 

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). 

Alitame (trade name Adame) is a water-soluble, crystalline powder of high sweetness potency (2000X, 10% sucrose solution sweetness equivalence). The sweet taste is clean, and the time—intensity profile is similar to that of aspartame. Because it is a stericaHy hindered amide rather than an ester, ahtame is expected to be more stable than aspartame. At pH 2 to 4, the half-life of aUtame in solution is reported to be twice that of aspartame. The main decomposition pathways (Fig. 6) include conversion to the unsweet P-aspartic isomer (17) and hydrolysis to aspartic acid and alanine amide (96). No cyclization to diketopiperazine or hydrolysis of the alanine amide bond has been reported. AUtame-sweetened beverages, particularly colas, that have a pH below 4.0 can develop an off-flavor which can be avoided or minimized by the addition of edetic acid (EDTA) [60-00-4] (97). 

Enhancers and Inducers. A sweetness enhancer is defined as a compound that imparts no taste per se, but when combined with a sweetener in small quantities, increases sweetness intensity. A tme sweetness enhancer has yet to be found. However, a good sweetness inducer, miraculin [143403-94-5] or [125267-18-7] (124), is known. Miraculin is a glycoprotein found in the fmit (called Miracle Fmit) of a West African shmb, chardella dulcifica. By itself, miraculin imparts no sweetness. When activated in the mouth by acidic substances, however, a sucrose-like sweetness is perceived. Thus, sour lemon, lime, grapefmit, rhubarb, and strawberry taste sweet when combined with miraculin. The taste conversion effect can last an hour or longer. 

In the confectionery industry, com symps are used extensively in nearly every type of confection, ranging from hard candy to marshmallows. In hard candies, which are essentially soHd solutions of nearly pure carbohydrates, com symp contributes resistance to heat discoloration, prevents sucrose crystallization, and controls hygroscopicity, viscosity, texture, and sweetness. Maltose symps, high conversion symps, and acid-converted symps (36 and 42 DE) are used for this appHcation. 

In the canning and preserving industries, com symps are used to prevent crystallization of sucrose, provide body, accentuate tme fmit flavors, and improve color and texture. In the beverage industry, the predominant use is in the beer and malt-Hquor areas. High conversion symps are used to replace dry cereal adjuncts, provide fermentable sugars, enhance flavor, and provide body. These symps contain controlled amounts of dextrose and maltose for proper fermentation. 

Acarbose and Miglitol These agents are specific inhibitors of intestinal glucosidases and reduce the conversion of sucrose and starch to glucose. Their main effect is a delay, not a complete inhibition, of the absorption of carbohydrates. Postprandial blood sugar excursions are effectively reduced. Because a small portion of the carbohydrates enters the colon, their microbial degradation frequently causes flatulence or... 

Sucrose caramels have been produced under anhydrous thermal conditions that are designed to maximize the content of fructose-rich oligosaccharides.100-102 These sucrose thermal oligosaccharide caramels (STOC) have been tested in animals as a nutritional supplement. Improved weight gains and feed conversion, and increased levels of bifidobacteria (see section VIII) were observed in broiler chickens that were fed this supplement.103... 

Cf Conversion fector of sucrose to acetate (g-acetate/g-sucrose) 1.05... 

Lager, I., Looger, L. L., Hilpert, M., Lalonde, S. and Frommer, W. B. (2006). Conversion of a putative Agrobacterium sugar-binding protein into a FRET sensor with high selectivity for sucrose. J. Biol. Chem. 281, 30875-83. 

No rate enhancement was observed when the reaction was performed under microwave irradiation at the same temperature as in conventional heating [47]. Similar reaction kinetics were found in both experiments, presumably because mass and heat effects were eliminated by intense stirring [47]. The model developed enabled accurate description of microwave heating in the continuous-flow reactor equipped with specific regulation of microwave power [47, 48]. Calculated conversions and yields of sucrose based on predicted temperature profiles agreed with experimental data. 

There are certain reactions, e.g. inversions of sucrose and methane etc. in which the rate of reactions were found to be proportional to the concentration of H+ ions. Similarly, there are reactions which are catalyzed by OH ions, e.g. conversion of acetone into diacetone alcohol or decomposition of nitroso-triacetoneamine. These are known as specific hydrogen ion catalyzed or specific hydroxyl-ion catalyzed reactions. Also there are some reactions in which both H+ and OFF ions act as catalysts probably along with water. The undissociated acid or base have negligible effect on the rate of reaction. The hydrolysis of ester is an example in which both H+ and OH ions act as catalyst... 

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