Specific Mass Growth Rate of Sugar Crystals: Probabilistic Modeling

Introduction. The present research featured industrial sugar crystallization. The article introduces a generalized mathematical model of specific growth rate of sugar crystals depending on temperature, solids, and the purity of solution, as well as on the concentration and average size of crystals. The model includes the probabilistic component of growth rate of monocrystals and the reduced adjustment of the constrained crystal growth depending on the abovementioned as-pects. Study objects and methods. The research focused on mass crystallization of sucrose, including the growth rate of monocrystals and the number of crystals in the fill mass. The obtained experimental data were processed using nonlinear programming. Results and discussion. 421 experiments made it possible to develop a probabilistic mathematical model of specific mass growth rate of sugar monocrystals and its dependence on the solution temperature, purity, and solids content. Model error: ± 11.3%. The model covers the temperature range, concentration of solids, and purity of the solution. The proximity of crystals was calculated according to the dependence of the growth rate on their concentration and the average size (error: ± 1.3%). The adjustment range: concentration of crystals = 5–60%, average size = 0.25–1.50 mm. Conclusion. The present generalized mathematical model of crystallization considered the temperature, as well as the purity and solids content in the fill mass, the concentration of sucrose crystals and their average size. The research compared the effect of linear size and concentration of sugar monocrystals on the calculated and experimental sizes of specific mass growth rate and the dimensionless adjustment of growth rate. The calculated sizes proved to be close to the ex-perimental data, which showed adequacy to the developed crystallization model. The research results can be used to optimize the process of mass sugar crystallization.

Effect of dextran and enzymatically decomposed dextran on the sucrose crystal shape

The effect of dextran’s molecular mass distribution on the sucrose crystal shape was key to this study. Therefore, sucrose crystals were produced by evaporating crystallization experiments using synthetic thick juices in the form of pure sugar syrups containing high (T2000) and low (T40) molecular mass dextran fractions as well as enzymatically decomposed dextran. The combined analysis of molecular mass distributions by size exclusion chromatography and sucrose crystal shapes by static image analysis were used to identify the least harmful reaction products resulting from the enzymatic decomposition of dextran. The combined evaluation of two shape parameters, circularity and width-to-length ratio, has shown that three different shape modifications can be related to the presence of dextran, namely cube-shaped crystals, elongated needle-shaped crystals and agglomerates. In the main, the data indicated that high T2000 contents and generally all T40 dextran contents led to an increased occurrence of agglomerated and occasionally elongated crystals. The latter was especially found for high T2000 dextran contents. In contrast, low T2000 dextran contents predominantly increased the amount of cube-like crystals. The enzymatic decomposition of dextran resulted in a gradual reduction of the molecular mass. It was shown that an insufficient decomposition to broadly distributed low molecular mass dextran fragments, which are realistic to assume for technical cane and beet juices, still dramatically affected the sucrose crystal shape. Once dextran was decomposed to molecules with molecular masses of less than 5 kDa, no dextran-related effects on the sucrose crystal shape were found.

Physico-Chemical Characteristics of White Sugar Fractions Separated by Crystal Sizes

According to the EU Council Directive 2001/111/EC, related to certain sugars intended for human consumption, a great attention is paid to color in sugar. On the other hand, the non-sucrose compounds having intensive color tend to build into the sucrose crystals. Since Serbia has to work on the new rules concerned sugar quality and harmonization with EU standards, some investigations on sugar crystals are carried out at the request of some sugar factories. Investigations are carried out on sugar crystal size dependence on sugar color and on dissolution rate of different sugar crystal size fractions with the aim to create new sugar products. In this study, sugar samples with different sugar color are divided into 5 fractions by crystal size, defining size distributions. In each fraction the color in solution and the type of color are measured, as well as other relevant physico-chemical parameters. The conclusion is that the sugar color type depends on the crystal size, but sugar crystal solution is not dependent on crystal size except a fraction smaller than 200 mm, which has 30-75% higher sugar color in solution than the other crystal size fractions.

Corrosion Properties of Ti Scaffolds Prepared with Sucrose as a Space Holder

In this work we shows procedure for new biomaterial - void metal composite (VMC) formation. We used a quasi-spherical sucrose crystals as a space holder material. In the process, titanium powder (different particle sizes) and sucrose were mixed together and uniaxially pressed to make a green compacts. In the next step the sucrose crystals were dissolved in water, leaving open spaces surrounded by metallic scaffold with different porosity (50 – 70%). Such prepared titanium scaffold was dried and sintered in vacuum. The foams morphology was investigated by SEM and CT. The corrosion tests of the as prepared materials were performed in Ringer`s solution using cyclic polarization measurements. We shows that Ti scaffolds prepared by using sucrose as a space holder have corrosion resistance comparable to bulk microcrystalline titanium.