Inversion sucrose

Acidic Cation-Exchange Resins. Brmnsted acid catalytic activity is responsible for the successful use of acidic cation-exchange resins, which are also soHd acids. Cation-exchange catalysts are used in esterification, acetal synthesis, ester alcoholysis, acetal alcoholysis, alcohol dehydration, ester hydrolysis, and sucrose inversion. The soHd acid type permits simplified procedures when high boiling and viscous compounds are involved because the catalyst can be separated from the products by simple filtration. Unsaturated acids and alcohols that can polymerise in the presence of proton acids can thus be esterified directiy and without polymerisation. 

Polarimetric determination of the sucrose concentration of a solution is vaUd when sucrose is the only optically active constituent of the sample. In practice, sugar solutions are almost never pure, but contain other optically active substances, most notably the products of sucrose inversion, fmctose and glucose, and sometimes also the microbial polysaccharide dextran, which is dextrorotatory. Corrections can be made for the presence of impurities, such as invert, moisture, and ash. The advantage of polarization is that it is rapid, easy, and very reproducible, having a precision of 0.001°. 

Viberg, U. and Sjoholm, I. 1998. Sucrose inversion during osmotic pre-treatment of strawberries. Lebensmittel-Wissenschaft Technol. 31, 546-551. 

Sucrose inversion, a typical proton-catalysed irreversible reaction... 

Effect of degree of crosslinking of the polymer catalyst on the rate coefficient (k) of sucrose inversion at 50°C [505]... 

Other results also confirm the important role of internal diffusion. Experimental activation energies (67—75 kJ mol"1) of the sucrose inversion catalysed by ion exchangers [506—509] were considerably lower than those of a homogeneously catalysed reaction (105—121 kJ mol"1) [505, 506,508] and were close to the arithmetic average of the activation energy for the chemical reaction and for the diffusion in pores. The dependence of the rate coefficient on the concentration in the resin of functional groups in the H+-form was found to be of an order lower than unity. A theoretical analysis based on the Wheeler—Thiele model for a reaction coupled with intraparticle diffusion in a spherical bead revealed [510,511] that the dependence of the experimental rate coefficient on acid group concentration should be close to those found experimentally (orders, 0.65 and 0.53 for neutralisation with Na+ and K+ ions respectively [511] or 0.5 with Na+ ions [510]). 

Intrinsic rate coefficients, feintr, of sucrose inversion catalysed by Dowex 50W-X8 were evaluated [506] by correcting the experimentally observed coefficients, feobs, using the relation... 

The mineral constituents of the raw cane juice persist in the final molasses. The principal difference in relative amounts of these substances in molasses arises from the use of lime in defecation which causes an increase in calcium. Egyptian cane molasses solids contained 0.66% of titanium.181 The cations are believed to complex with the sugars and to thus inhibit the crystallization of sucrose, which latter is known to form compounds with inorganic salts, such as its well known compound with sodium chloride. Decationization of cane juice with ion exchange resins greatly reduces molasses formation but sucrose inversion is a concomitant problem.182... 

Kouassi, K., Roos, Y.H. Glass transition and water effects on sucrose inversion by invertase in a lactose-sucrose system./. Agric. Food Chem. 48, 2461-2466, 2000... 

A particular confectionery industry problem is the long product life. A long-established product, initially made by a batch process, must retain the same qualities when prepared by a more modern continuous plant process, and a great deal of work can go into making the two products exactly the same. In general, however, the continuous plants are more effective at heating the product and produce less sucrose inversion, although, even after the recipe has been adjusted to account for this, textural differences sometimes persist. 

The basic mechanism for enzyme-catalyzed reactions was first proposed by Michaelis and Menten and confirmed by a study of the kinetics of the sucrose inversion. A simple reaction mechanism by which an enzyme converts a reactant S, usually called a substrate, into products P is... 

Acid-Catalyzed Reaction. A number of enzyme-catalyzed reactions, including the sucrose inversion to be studied in this experiment, can also be carried out under non-physiological conditions by using H ions as a less efficient catalyst. In the present case, the acid-catalyzed reaction rate has the form... 

Crystallization. The filtered thick juice is now sent to the vacuum-pan for boiling. It is essential to use low temperatures (65 to 80°C) in this process to avoid sucrose inversion and caramelization. Pan boiling and crystallization practices are very similar to the same unit process in the sugarcane refinery described earlier for cane sugar. Crystallization is continued until the crystals have reached the required size. This mixture of crystals and mother liquor, known as massecuite, is discharged into a mixer tank and from there it is sent to centrifugal separators. In... 

A special case arises when the "skin" (membrane) layer of a normal composite membrane element is immobilized with a catalyst and not intended for separating reaction species. Consider the example of an enzyme, invertase, for the reaction of sucrose inversion. Enzyme is immobilized within a two<layer alumina membrane element by filtering an invertase solution from the porous support side. After enzyme immobilization, the sucrose solution is pumped to the skin or the support side of the membrane element in a crossflow fashion. By the action of an applied pressure difference across the element, the sucrose solution is forced to flow through the composite porous structure. Nakajima et al. [1988] found that the permeate direction of the sucrose solution has pronounced effects on the reaction rate and the degree of conversion. Higher reaction rates and conversions occur when the sucrose solution is supplied from the skin side. The effect on the reaction rate is consistently shown in Figure 11.6 for two different membrane elements membrane A is immobilized by filtering the enzyme solution from the support layer side while membrane B from the skin layer side. 

Figure 11.6 Effect of permeate direction on reaction rate of sucrose Inversion (circles refer to membrane A and triangles to membrane B open symbols are associated with permeate flow from skin layer side and filled symbols from support layer side) [Nakajimactal., 1988]...

P8C-3 In an article on the kinetics of sucrose inversion by invertase with multiple steady sates in a CSTR [Chem. Eng. Common., 6, 151 (1980)], consider the following challenges Are the equations for Jf and K correct If not, what are the correct equations for these variables Can an analysis be applied to this. system to deduce regions of multiple steady statra ... 

The sucrose inversion has been extensively studied from the viewpoint of electrolyte effects (Guggenheim and Wiseman, 2), the application of the Arrhenius equation to the reaction (Leininger and Kilpatrick, 3), and the catalytic effects of acid molecules (Hammett and Paul, 4). It is probable that, in aqueous solution, we are dealing with a case of specific hydrogen ion catalysis and can postulate the equilibrium (Gross, Steiner, and Suess, 5)... 

Chromatographic batch reactors are employed to prepare instable reagents on the laboratory scale (Coca et al., 1993) and for the production of fine chemicals. These applications include the racemic resolution of amino acid esters (Kalbe et al., 1989), acid-catalyzed sucrose inversion (Lauer, 1980), production of dextran (Zafar and Barker, 1988) and saccharification of starch to maltose (Sarmidi and Barker, 1993a). Sardin et al. (1993) employed batch chromatographic reactors for different esterification reactions such as the esterification of acetic acid with ethanol and the transesterification of methylacetate. Falk and Seidel-Morgenstern (2002) have investigated the hydrolysis of methyl formate. 

The chromatographic SMB reactor has been examined for various reaction systems, with the main focus on reactions of the type A + B C + D. Examples are esterifications of acetic acid with methanol (Lode et al., 2003b), ethanol (Mazotti et al., 1996a) and (5-phenethyl alcohol (Kawase et al., 1996) as well as the production of bisphenol A (Kawase et al., 1999). The same reaction type can also be found for various hydrocarbons, such as the transfer reaction of sucrose with lactose to lactosuc-rose (Kawase et al., 2001) and the hydrolysis of lactose (Shieh and Barker, 1996). Barker et al. (1992) focused on reactions of the type A B + C, such as enzyme-catalyzed sucrose inversion and the production of dextran. Also, reactions of the type A tB have been investigated, e.g. isomerization of glucose to fructose by Fricke (2005) as well as Tuomi and Engell (2004). Michel et al. (2003) have examined the application of electrochemical SMB reactors for consecutive reactions and used as an example the production of arabinose. 

CACR - equilibrium dispersive A + B 2C + D Linear Validated for sucrose inversion Sarmidi and Barker (1993b)... 

It has been known for many years that ultrasound can be employed as a method of inhibiting enzyme activity. Nearly 60 years ago Chambers reported that pure pepsin was inactivated by sonication probably as a result of cavitation [14]. Enzyme inactivation through sonication is also considered to be responsible for the inhibition of sucrose inversion [15]. 

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