Inversion of sucrose

Candy. Citric acid is added in candy for tartness (54,55). To suppress the inversion of sucrose, it should be added after the cook, at levels from 0.5 to 2.0%. The pH of pectin gel candies is adjusted with citric acid for maximum gel strength. 

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. 

Enzyme catalysis. Enzymes are proteins, polymers of amino acids, which catalyze reactions in living organisms-biochemical and biological reactions. The systems involved may be colloidal-that is, between homogeneous and heterogeneous. Some enzymes are very specific in catalyzing a particular reaction (e.g., the enzyme sucrase catalyzes the inversion of sucrose). Enzyme catalysis is usually molecular catalysis. Since enzyme catalysis is involved in many biochemical reactions, we treat it separately in Chapter 10. 

For the inversion of sucrose in the presence of HCI the tabulated polarimeter readings, a, were obtained at the times shown. Find the specific rate. 

Applying physiological conditions regarding substrate concentration, solvent and temperature, the enzymatic inversion of sucrose is practically irreversible. 

Thus, if optically active substance is involved in the reaction, the change in optical rotation can be used directly to follow the progress of reaction. The inversion of sucrose in presence of HC1 giving rise to fructose and glucose can, thus, be monitored polarimetrically. 

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... 

Both acid- and base-promoted reactions may be affected by acidic surfaces and, hence, by the factors which influence the surface acidity. Kinetic evidence for increased Br nsted acidity at clay surfaces has been presented by McAuliffe and Coleman (80) who studied the hydrolysis of ethylacetate and the inversion of sucrose. They noted that potentionmetrie pH measurements did not explain the catalytically effective H+-concentration at the clay surface. 

For different feed compositions, a maximum value of PR was found for a feed ratio of 40/60. This demonstrates the existence of an optimum. The results obtained in this study were compared with the simulation of an SMB bioreactor for the inversion of sucrose to fructose and glucose and found to be consistent [160]. 

The same group also performed experiments with a continuous chromatographic reactor of the SMBR type [133,174]. The system used consisted of 12 columns with inner diameters of 5.4 cm and a length of 75 cm. Approximately 12 cycles were necessary for stabilization of the system. Complete inversion of sucrose even at feed concentrations of up to 55% w/v was achieved, while the product purity was over 90%. After prolonged usage, the system efficiency decreases due to the loss of the calcium ions from the matrix and a consequent decreased selectivity of the resin. However, this problem could be overcome by regeneration of the resin with calcium nitrate. 

Several papers investigating the inversion of sucrose into glucose and fructose appeared a decade ago [133,174, 175]. The reaction is performed using the enzyme invertase according to the following reaction ... 

Several types of reaction may be carried out in a chromatographic reactor. The reaction can be chemical or biochemical, taking place on the stationary phase, in the mobile phase, or both. The stationary phase must be chosen to have a good retention (affinity) for at least one component of the reaction system, and in some cases it has to act as a catalyst or catalyst support. Chromatographic reactors are particularly suited to enzyme-catalysed reactions such as the inversion of sucrose and biosynthesis of dextran, to various... 

The idea that an activated complex or transition state controls the progress of a chemical reaction between the reactant state and the product state goes back to the study of the inversion of sucrose by S. Arrhenius, who found that the temperature dependence of the rate of reaction could be expressed as k = A exp (—AE /RT), a form now referred to as the Arrhenius equation. In the Arrhenius equation k is the forward rate constant, AE is an energy parameter, and A is a constant specific to the particular reaction under study. Arrhenius postulated thermal equilibrium between inert and active molecules and reasoned that only active molecules (i.e. those of energy Eo + AE ) could react. For the full development of the theory which is only sketched here, the reader is referred to the classic work by Glasstone, Laidler and Eyring cited at the end of this chapter. It was Eyring who carried out many of the... 

Hydrolysis of sucrose yields glucose and fructose with specific rotations [q ]d + 52.5° and —92°, respectively, and makes the resulting mixture laevorotatory (—). This phenomenon of sucrose is called the inversion of sucrose, and the resulting mixture is known as invert sugar, which is the main component of honey, and is sweeter than sucrose itself. 

Inversion of sucrose High temperature and low Work at room temperature, and... 

Shalaev et al. (37) examined the influence of citric acid on the acid-catalyzed inversion of sucrose in the freeze-dried solid state. Even with less than 0.1% residual moisture, the colyophilization of sucrose with acidic substances can produce reducing sugars capable of further reaction with other formulation components that are susceptible to such reactions. 

Shalaev EY, Lu Q, Shalaeva M, Zografi G. Acid catalyzed inversion of sucrose in the amorphous state at very low levels of residual water. Pharm Res 2000 17 366-370. 

Sol. The inversion of sucrose will be a first order reaction if the above data conforms to the equation,... 

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