Diffusion Coefficient Of Sucrose Research Articles

Simulation of mass transfer during sucrose extraction from sugar beet using a combined analytical and semi-empirical model

In this study, the leaching of sucrose from sugar beet was investigated in a batch process using distilled water solvent. Extraction kinetics was explored at low and high solutions/solid mass ratios. The experimental data were examined by a mathematical model based on Fick’s second law and the Azuara model as a semi-empirical model to determine diffusion coefficients, equilibrium concentrations, and dissociation coefficient K (the ratio of the concentration at the sample to concentration in solution). Diffusion coefficients were calculated by nonlinear regression of the experimental findings. The diffusion coefficients of sucrose (ranging from 2.4831 × 10−10 to 3.2023 × 10−10 m2/s) were higher in the high solution/solid mass ratios compared to the low ratios (ranging from 0.5231 × 10−10 to 0.8728 × 10−10 m2/s) due to higher mass transfer driving force. Also, the proposed empirical Azuara model could properly describe equilibrium concentrations by predicting results (squared mean square error less than 0.0082) close to experimental data at different operating conditions.

Hydrolysis of Sucrose over Sulfonic Acid Resins

AbstractSucrose hydrolysis on acidic ion‐exchange resins is a long‐established process in the sugar industry, but the formation of side products is less understood. A resin typically used in the industrial process (C124SH, Purolite) was investigated in a broad range of sucrose concentration (7 to 75 % w/w) and temperatures from 25 to 80 °C. Fructose is converted to 5‐hydroxymethylfurfural (HMF) due to a 1/2 order reaction. This is explained by the formation of a fructose disaccharide (monoanhydride) as an intermediate decomposing to HMF and fructose. Difructose dianhydrides (DFAs) are separately formed as prevailing by‐products. The color of the product mixture is correlated to HMF and found to be reduced by size exclusion inside the resins. Diffusional limitations of the total reaction are investigated by comparison of the entire resin bead with its size‐reduced forms obtained by milling. Without diffusion limitation the catalytic activity increases with the sugar concentration while the diffusion control leads to a maximal activity around 40 % w/w sugar. Diffusion coefficients of sucrose are calculated.

Preserving Melons by Osmotic Dehydration in a Ternary System Followed by Air-Drying

In this study, the effect of different osmotic solution concentrations (20–60% w/w of sucrose with 10% w/w NaCl salt), fruit to solution ratios (1:9–1:3), immersion times (0.5–4 h), and temperatures (15–55°C) on the mass transfer kinetics during osmotic dehydration of melons (Curcumis melo L.) in ternary solution namely sucrose–salt–water followed by air-drying were investigated. The effective diffusion coefficients for sucrose and water during osmotic dehydration were determined, assuming osmotic dehydration to be governed by Fickian diffusion. The estimated parameters allowed optimizing the system to reduce total processing time. The optimum treatments were with 50% sucrose and 10% NaCl salt concentration, fruit to solution ratio of 1:4 for 1 h at 45°C. Samples non-treated and pre-treated in optimized conditions were dried in a hot-air dryer at 60°C until equilibrium was achieved after 2.5 h. Pre-treatment reduced the air-drying period in up to 6.8 h.

Mass Transfer Modeling During Osmotic Dehydration of Hexahedral Pineapple Slices in Limited Volume Solutions

The study of mass transfer during osmotic dehydration process in limited volume solutions was carried out to evaluate the diffusion coefficients of sucrose and water in the osmotic treatment of hexahedral pineapple slices. The experimental osmotic dehydration kinetics for pineapple slices of two different sizes were conducted at 25 °C using a 1:1 solution to fruit weight ratio. The analytical solution of a 3D mass transfer model considering a limited volume of osmotic solution (i.e., an osmotic media of variable solute concentration) was used for describing the mass transfer in osmotic dehydration of pineapple slices. This model was fitted to the experimental kinetics by means of nonlinear regression to obtain the diffusion coefficients. Additionally, the diffusion coefficients were evaluated considering an infinite volume of osmotic solution (i.e., an osmotic media of constant solute concentration). Results showed that the proposed model may be fitted accurately to the experimental osmotic dehydration kinetics and allows the estimation of diffusion coefficients when solute concentration in the osmotic media varies along the process.

Mass transfer in osmotically dehydrated apple stored at temperatures above zero

Material dehydrated in sucrose solution by osmosis for 3 h at 30 °C and for 1 h at 70 °C was stored for 24, 72 and 144 h at 5, 9, 15 and 20 °C. Internal gradients of dry matter and sucrose concentration caused mass transfer in the material. Dry matter content in the surface layers was close to 40%, while sucrose concentration was between 20% and 23%. At the distance of 10 mm from the mass transfer surface dry matter content was still higher than that in raw apple, but sucrose concentration was that of raw apple. Concentration profiles of sucrose changed with time and storage temperature. The higher was the temperature the faster was the diffusion of sucrose. In material osmosed at 30 °C for 3 h and stored for 72 h at 5, 9 and 15 °C sucrose concentration gradients were still present. However, after 144 h at 9 °C the concentration of sucrose became independent on the distance from the mass exchange surface. Diffusion of sucrose in material osmosed at 70 °C for 1 h was much faster than that observed in samples osmosed at lower temperature. The effective diffusion coefficient of sucrose was dependent on temperature and time of storage, and distance from the mass transfer surface as well. Since distance was related to concentration a relationship between sucrose concentration and effective diffusion coefficient was found. The effective diffusion coefficient was of the order of 10 −9–10 −12 m 2/s.

Mass Tansfer Characteristics of a Microchannel Device of Split‐Flow Type

AbstractA solute was transferred from an aqueous solution to deionized water in a microchannel device with a rectangular channel of 200 μm × 200 μm. The two liquid layers flowed in parallel within the rectangular channel. After making contact in the channel, the layers were split into two streams through a knife‐edge. The amount of solute transferred was determined by analyzing liquid samples taken from the outlet. Thus, conventional analytical instruments were readily available for obtaining the total concentration. Mass tansfer characteristics were examined through the measurement of diffusion coefficients for several solutes. Although the two liquids were carefully supplied at the same velocity, equal flow splitting was difficult to obtain. The unequal splitting led to scattering of the observed solute concentrations at a fixed supply flow rate. This could be a serious drawback as a mass tansfer device; however, a method was proposed to choose an appropriate value for equal splitting. The ratio of effluent flow rate of one liquid to another was changed intentionally. The solute concentration in the receiving liquid for the flow rate ratio of unity corresponds to the data for equal flow splitting. On the basis of the solute concentrations defined, the diffusion of benzoic acid was successfully analyzed using a conventional penetration model with a correction parameter. Furthermore, diffusion coefficients for sucrose and glycine were determined using the basic equation obtained with benzoic acid. The observed values compared fairly well with reported ones. The correction parameter expresses characteristics of the microchannel device; however, the physical picture is still unclear.

Water Diffusion and Desorption Behavior during Low-Temperature Drying of Foods

The water diffusion and the water desorption behavior of sugars and pasta-like foods for temperatures between 283 K and 323 K were investigated by isothermal drying experiments and desorption isotherm measurement. The equilibrium water content in low water activity increased with a decrease in temperature for sucrose and maltodextrin whereas the values did not change significantly with temperature for pasta-like foods. The water diffusion coefficient of sucrose was much lower than those of pasta-like foods. Because of these two factors, the drying rates at low temperatures for pasta-like foods were higher than those for sucrose.

Concentration profiles and effective diffusion coefficients of sucrose and water in osmo-dehydrated apples

The spatial distribution of water and sugars in half-fresh apples dehydrated in sucrose solutions (30% and 50% w/w, 27 °C) for 2, 4 and 8 h, was determined. Each half was sliced as from the exposed surface. The density, water and sugar contents were determined for each piece. A mathematical model was fitted to the experimental data of the water and sucrose contents considering the overall flux and tissue shrinkage. A numerical method of finite differences permitted the calculation of the effective diffusion coefficients as a function of concentration, using material coordinates and integrating the two differential equations (for water and sucrose) simultaneously. The coefficients obtained were one or even two orders of magnitude lower than those for pure solutions and presented unusual concentration dependence. The behaviour of the apple tissue was also studied using light microscopy techniques to obtain images of the osmotically treated pieces (20%, 30% and 50% w/w sucrose solutions for 2, 4 and 8 h).

Modeling of Sucrose Permeation through a Pectin Gel During Ultrafiltration of Depectinized Mosambi [Citrus sinensis (L.) Osbeck] Juice

ABSTRACTUltrafiltration of synthetic juice (mixture of sucrose and pectin with varying composition) as well as enzymatically treated mosambi [Citrus sinensis (L.) Osbeck] juice is performed in a batch, unstirred membrane cell. Thin‐film composite polyamide membrane of molecular weight cutoff 50000 was used. The flux decline mechanism is found to be controlled by the growth of a gel layer of pectin over the membrane surface. Using standard cake filtration theory, the flux decline and the growth of gel layer is quantified. The gel layer is characterized in terms of specific gel layer resistance, gel porosity, and gel density. A transient model is proposed and solved numerically to quantify the transport of sucrose through the pectin gel for the synthetic juice and enzymatically treated juice. The hindered diffusion coefficient of sucrose through the gel is calculated by comparing the results with the experimentally obtained permeate concentration profile of sucrose. The calculated permeate concentration profile agrees well with the experimental data.

Evaluation of water and sucrose diffusion coefficients during osmotic dehydration of jenipapo ( Genipa americana L.)

The apparent diffusion coefficients for sucrose and water during osmotic dehydration of jenipapos were determined. Long time experiments (up to 60 h) were carried out in order to determine equilibrium concentrations inside jenipapos, whereas short time experiments (up to 4 h) were performed to provide detailed information on kinetics of water loss and solids gain at the beginning of osmotic treatment. According to the results, mass transfer rates for water and solutes, as well as the apparent diffusion coefficients for sucrose showed to be dependent on sucrose concentration in osmotic solution. The immersion time did not have significant effect ( p > 0.05) over the diffusion coefficients for sucrose and water.

Diffusion coefficients during osmotic dehydration of tomatoes in ternary solutions

The apparent diffusion coefficients for sucrose, NaCl and water during osmotic dehydration of tomatoes in ternary solutions were determined. Long time experiments (up to 60 h) were carried out in order to determine equilibrium concentrations inside tomatoes, whereas short time experiments (up to 4 h) were performed to provide detailed information on kinetics of water loss and solids gain at the beginning of osmotic treatment. The mass transfer rates for water and solutes showed to be dependent of NaCl and sucrose concentrations in osmotic solution and simple regression models as functions of solutes concentration were determined for diffusion coefficients. Salt and sucrose diffusivities showed to be interdependent, with increasing NaCl concentration causing the enhancement of water loss, at the same time that higher sucrose contents hindered the excessive salt penetration.

Diffusion of Sucrose and α,α-Trehalose in Aqueous Solutions

Diffusion coefficients for sucrose and trehalose in aqueous solutions were measured using pulsed-gradient-spin-echo NMR and calculated using molecular dynamics simulations. The diffusion coefficients of sucrose and trehalose are comparable at low disaccharide concentrations but differ from each other with increasing concentration and decreasing temperature. At 400 K and the highest disaccharide concentration considered in this work (80 wt %), the simulated trehalose diffusion coefficient is a factor of 3.5 smaller than that of sucrose (2.6 × 10-8 cm2/s and 9.3 × 10-8 cm2/s, respectively). In a 74 wt % disaccharide solution, the experimental diffusion coefficient for trehalose is a factor of 3 smaller than that of sucrose at 358 K. The diffusion coefficients of water are at least 1 order of magnitude larger than those of the disaccharides. This difference increases to 2 orders of magnitude at the highest disaccharide solutions considered here. The decoupling of the water and disaccharide motion is attribut...

Mass Transfer During Sucrose Infusion into Potatoes under High Pressure

ABSTRACT: The diffusion coefficient of sucrose in potato cylinders was determinted at the various pressures (200 to 600 MPa) and temperatures (20, 40, and 60 °C). Application of pressure opened up the tissue structure and facilitated diffusion. However, higher pressures above 400 MPa also induced starch gelatinization and hindered diffusion. The maximum diffusion coefficient was therefore, dependent on which of the 2 effects dominated. In this study, the maximum value of diffusion coefficient observed represented an 8‐fold increase over ambient values. Thus, application of appropriate levels of pressure (100 to 400 MPa), can be used to accelerate mass transfer during ingredient infusion into foods.

Pseudo-streaming potentials in Necturus gallbladder epithelium. I. Paracellular origin of the transepithelial voltage changes.

Apparent streaming potentials were elicited across Necturus gallbladder epithelium by addition or removal of sucrose from the apical bathing solution. In NaCl Ringer's solution, the transepithelial voltage (Vms) change (reference, basolateral solution) was positive with sucrose addition and negative with sucrose removal. Bilateral Cl- removal (cyclamate replacement) had no effect on the polarity or magnitude of the Vms change elicited by addition of 100 mM sucrose. In contrast, bilateral Na+ removal (tetramethylammonium [TMA+] replacement) inverted the Vms change (from 2.7 +/- 0.3 to -3.2 +/- 0.2 mV). Replacement of Na+ and Cl- with TMA+ and cyclamate, respectively, abolished the change in Vms. Measurements of cell membrane voltages and relative resistances during osmotic challenges indicate that changes in cell membrane parameters do not explain the transepithelial voltage changes. The initial changes in Vms were slower than expected from concomitant estimates of the time course of sucrose concentration (and hence osmolality) at the membrane surface. Paired recordings of the time courses of paracellular bi-ionic potentials (partial substitution of apical Na+ with tetrabutylammonium [TBA+]) revealed much faster time courses than those produced by sucrose addition, although the diffusion coefficients of sucrose and TBACl are similar. Hyperosmotic and hypoosmotic challenges yielded initial Vms changes at the same rate; thereafter, the voltage increased with hypoosmotic solution and decreased with hyperosmotic solution. These late voltage changes appear to result from changes in width of the lateral intercellular spaces. The early time courses of the Vms changes produced by osmotic challenge are inconsistent with the expectations for water-ion flux coupling in the junctions. We propose that they are pseudo-streaming potentials, i.e., junctional diffusion potentials caused by salt concentration changes in the lateral intercellular spaces secondary to osmotic water flow.

Effective diffusion coefficient of sucrose in calcium alginate gel

The effective diffusion coefficient of sucrose in 5% calcium alginate gel containing 41.6 g.d.c. l −1 Saccharomyces cerevisiae was investigated. Both free and immobilized S. cerevisiae in 0.175 cm and 0.3 cm diameter particles were used and the reactions were achieved in a medium containing 100 g l −1 sucrose and 0.05 m CaCl 2. With the assumption that the microorganisms did not grow or die in this medium, the results were analyzed according to Michaelis-Menten kinetics and the values of the parameters were determined as: V m = 0.256 g ml −1 gel h −1, K m 0 = 0.097 g ml −1, K m 1 = 0.125 g ml −1, and K m 2 = 0.165 g ml −1. Using these values, effectiveness factors were calculated as η 1 = 0.89 and η 2 = 0.76, and effective diffusion coefficients for sucrose in calcium alginate gel were determined as D e 1 = 4.1 × 10 −6 cm 2 s −1 and D e 2 = 4.0 × 10 −6 cm 2 s −1, for the particle size involved.

Diffusion of sucrose in xanthan gum solutions

Molecular diffusion of solutes, like sucrose in the xanthan gum fermentation, is important in order to understand the complex behavior of mass transfer mechanisms during the process. This work was focused to determine the diffusion coefficient of sucrose, a carbon source for xanthan production, using similar sucrose and xanthan concentrations to those occurring in a typical fermentation. The diaphragm cell method was used in experimental determinations. The data showed that diffusion coefficient of sucrose significantly decreases when xanthan gum concentration increases. Theoretical and semiempirical models were used to predict sucrose diffusivity in xanthan solutions. Molecular properties and rheological behavior of the system were considered in the modeling. The models tested fitted well the behavior of experimental data and that reported for oxygen in the same system.

Diffusion of sugars and acids in human dental plaque in vitro

Using a clearance technique, diffusion coefficients, D, were measured in plaque samples in which metabolic activity was eliminated by fixation with glutaraldehyde. Diffusion coefficients for sucrose, sodium acetate and sodium lactate at 37 °C were 3.0, 5.0 and 4.8 × 10 −6 cm 2s −1, respectively. Diffusion rate in plaque was between 2- and 5-fold slower than in water with uncharged species retarded less than charged species. However, diffusion in thin layers of plaque (100 μm) was rapid with clearance-halving times, T 1 2 , of about 6 s for acetate and lactate and 9 s for sucrose. Acetic and lactic acids diffuse faster than sucrose in plaque. Thus, the prolonged lowering of plaque pH following exposure to dietary carbohydrate is due to continued acid production in the plaque rather than to a restriction of diffusion of acid.

The diffusion coefficient of sucrose in water. A physical chemistry experiment

In this paper, the authors present an experiment that focuses on the diffusion of a solute in a liquid solution is governed by the same basic laws as gaseous diffusion.

Diffusion of sucrose, sodium, and water in ventricular myocardium

Fundamental to the analysis of capillary-tissue exchanges is a knowledge of tissue transfer rates by diffusion outside the capillaries (2, 30). The purpose of this work was to determine the apparent tissue diffusion coefficients for sucrose, sodium, and water at body temperature in the cat myocardium. The studies were made in a diffusion cell (32) on a sheet of cat myocardium by a method modified from that described by Page and Bernstein (26). These authors found at 23°C that sodium did not enter the cells and that the steady-state diffusion of water, sodium, and sucrose could be accounted for by fluxes occurring only in the extracellular space. Since cell membrane permeability to water is so high that restriction of water diffusion to the extracellular space seemed unlikely, we felt that a study of the three tracers simultaneously at 37°C was needed.

Diffusion studies of bile acids, fatty acids and sucrose-NaCl-water systems at 37 °C by a modified capillary cell apparatus and their application to membrane transport studies

A capillary cell apparatus is described that allows accurate measurement of solute tracer diffusion coefficients in biological solutions at 37 °C. The apparatus has a unique stirring mechanism to provide a uniform flow pattern over the capillaries with only 18 ml of the bulk solution. Four capillaries of 2 cm length are used. With this apparatus measurement can be made at relatively short time periods so that bacterial overgrowth in the solutions is minimized. Using this apparatus tracer diffusion coefficients of three bile acids, cholic, taurochollic and taurodeoxycholic acids, and four fatty acids, acetic, pentanoic, octanoic and decanoic acids, were measured in an isotonic phosphate buffer, pH 7.1, at 37 °C. Viscosity, density and diffusion coefficients of sucrose in physiological saline solutions were also measured.