Hydrolysis sucrose

High alkalinities of limed juice serve several functions. Foremost is to retard sucrose hydrolysis, one of the oldest reactions in the Uterature of chemical kinetics (6). Sucrose hydrolysis proceeds much more slowly at a moderately high pH than at an even slightly acidic pH. 

Enzymes. Invertase (P-fmctofuranosidase) is commercially produced from S. cerevisiae or S. uvarum. The enzyme, a glycoproteia, is not excreted but transported to the cell wall. It is, therefore, isolated by subjecting the cells to autolysis followed by filtration and precipitation with either ethanol or isopropanol. The commercial product is available dry or ia the form of a solutioa containing 50% glycerol as a stabilizer. The maia uses are ia sucrose hydrolysis ia high-test molasses and ia the productioa of cream-ceatered candies. 

FIG. 7-2 Linear analysis of catalytic rate equations, a), (h) Sucrose hydrolysis with an enzyme, r = 1curve-fitted with a fourth-degree polynomial and differentiated for r — (—dC/dt). Integrated equation,... 

Early reports on levan are obscured by incomplete descriptions of impure products.2 96 Greig-Smith found that Bacillus levaniformans(1) produced levan from sucrose96" in suitable nutrient solutions, but not from D-glucose, D-fructose, lactose or maltose.966 He therefore assumed that levan could only be formed from the nascent D-fructose and D-glucose resulting from the inversion of sucrose. Hydrolysis of levan yielded D-fructose only, and analysis of levan agreed with the empirical formula (C HiriOi) it was noted that levan was closely related to inulin but was not identical with it. 

Sucrose hydrolysis is catalyzed by an enzyme. Time- concentration data are given in the first two columns. The applicability of the M-M equation, r = kC/(M+C), is to be checked. 

Chen, Y.H., Aull, J.L., and Bell, L.N. 1999. Invertase storage stability and sucrose hydrolysis in solids as affected by water activity and glass transition. J. Agric. Food Chem. 47, 504-509. 

Sucrose acrylate derivatives, 23 480 Sucrose concentration, polarimetric determination of, 23 473 Sucrose derivatives, 23 480 Sucrose esters, 23 480 Sucrose hydrolysis, 23 462 Sucrose monoesters (SMEs), 23 480, 481 Sucrose polyester, 23 481 Sucrose separation... 

After sucrose hydrolysis by the invertase enzyme in solution, perform all measurements at a constant applied potential of +0.60 Y in order to oxidase the hydrogen peroxide produced by the enzyme reaction of glucose oxidase biosensors (Scheme 20.1). 

Commercial yeast invertase (Bioinvert ) was immobilized by adsorption on anion-exchange resins, collectively named Dowex (1x8 50-400,1x4 50-400, and 1x2 100-400). Optimal binding was obtained at pH 5.5 and 32°C. Among different polystyrene beads, the complex Dowex-1x4-200/invertase showed a yield coupling and an immobilization coefficient equal to 100%. The thermodynamic and kinetic parameters for sucrose hydrolysis for both soluble and insoluble enzyme were evaluated. The complex Dowex/inver-tase was stable without any desorption of enzyme from the support during the reaction, and it had thermodynamic parameters equal to the soluble form. The stability against pH presented by the soluble invertase was between 4.0 and 5.0, whereas for insoluble enzyme it was between 5.0 and 6.0. In both cases, the optimal pH values were found in the range of the stability interval. The Km and Vmax for the immobilized invertase were 38.2 mM and 0.0489 U/mL, and for the soluble enzyme were 40.3 mM and 0.0320 U/mL. 

Table 1 shows that some Dowex/invertase complexes, in which the resins used were 1x2-200, 1x4-50, 1x4-100, 1x4-200, 1x8-50, and 1x8-200, retained 100% of protein molecules during sucrose hydrolysis. The absence of enzyme desorption from the support enhances the half-life of the immobilized complex when employed in repeated-batch or continuous processes (18). 

In the presence of a H-Y zeolite with a Si/Al ratio of 15, we have performed the hydrolysis of other fructose and glucose precursors under operating conditions quite close to those used for sucrose hydrolysis. It was found that aqueous solutions of inulin, maltose, cellobiose and starch (50-l20gL L) were hydrolysed into the corresponding monosaccharides within 30-150 min at temperatures between 90 °C and 150 °C in the presence of 0.5-2.5 g of catalyst in 50 ml of starting solution, with yields of monosaccharides from 92 to 98%.[12]... 

Both fructooligosaccharide synthesis and sucrose hydrolysis are catalyzed by most of the fructosyltransferases and 3-fmctofuranosidases (invertases) in the presence of sucrose. The transferase hydrolase raho, which determines the maximum yield of fructooligosaccharide, depends basically on two parameters the concentra-hon of sucrose and the intrinsic enzyme properties, that is its ability to bind the nucleophile (to which a fructose is transferred) and to exclude H2O from the acceptor binding site [11]. 

Stefuca et al. (1990) proposed an ET method offering a rapid, convenient, and general approach to determine kinetic constants of immobilized biocatalysts. Here, a differential reactor (DR) was used for the measurement of the initial reaction rate of sucrose hydrolysis (Vallat et al. 1986). The enzyme column of the ET has been considered as a differential packed-bed reactor, and with a mathematical model, intrinsic kinetic constants of immobilized invertase were calculated from experimental DR and ET data. 

The method was confirmed experimentally with sucrose hydrolysis catalyzed by invertase, that had been immobilized by biospecific binding on concanavalin A-bead cellulose. Figure 6B shows good agreement between the substrate concentration determined by the conversion of thermometric signals of Fig. 6A and those obtained by spectrophotometric analysis. From the data shown in Fig. 6B, the initial rate was determined to be v0 = 0.775 mM min1. Introducing this value into Eq. (23), vobs was calculated and the value of the transformation parameter a was determined from Eq. (24). 

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