Viscosities of aqueous solutions of sucrose and sodium chloride of interest in osmotic dehydration processes

doi:10.1016/S0260-8774(01)00221-7

Journal of Food Engineering

Volume 54, Issue 4, October 2002, Pages 347-352

https://doi.org/10.1016/S0260-8774(01)00221-7 Get rights and content

Abstract

Osmotic dehydration of food involves the utilization of solutions with one or several solutes that increase considerably the viscosity of the liquid phase. As commercial sugar and sodium chloride are the common solutes employed in this type of processes, kinematic viscosities of binary and ternary aqueous solutions of these solutes were measured at various concentrations (from 0 up to 4.5 $mol kg^{−1}$ at 0.5 $mol kg^{−1}$ intervals) and temperatures (from 20 up to 50 °C). Additionally, densities of each solution at 25 °C are reported. Experimental data were simultaneously correlated with concentration and temperature for binary and ternary solutions with a satisfactory accuracy.

Introduction

Osmotic dehydration of food (mainly fruits and vegetables) is a convenient method of improving the quality of a product since nutritional, organoleptic and physical aspects are preserved better than when using other dehydration methods (Raoult-Wack, 1994). Also, the economics of the process were positive compared to other dehydration methods (Lazarides, Gekas, & Mavroudis, 1997). During osmotic treatment several flows occur simultaneously: loss of water from the product to the hypertonic solution, solute impregnation from the solution to the product surface and, additionally, loss of other compounds (mainly soluble solids) from the product to the solution. The mass flow rates depend on several factors such as solution concentration (and, associated physical properties such as density and viscosity), temperature, contact time, level of agitation, sample size and geometry, solution to solid volume ratio and operating pressure. Certainly, the viscosity is an important physical property that influences the required agitation power (economic aspect), and the mass transfer rate. When the osmotic media is highly viscous the global mass transport must be studied as transport in two phases (liquid and solid phase). For this reason, the common assumption that the external resistance to mass transfer is negligible is not always valid.

The two most common solutes in these processes are sugars (mainly sucrose) and salts (mainly sodium chloride) used as binary or as ternary solutions. Sodium chloride solutions present lower water activity and higher osmotic pressure than sucrose solutions. Unfortunately, sodium chloride penetrates into the bulk of the solid whereas sucrose, due to the molecular size, doesn't exhibit this behaviour. Aqueous solutions with sucrose and sodium chloride are interesting because they improve the water loss with low solid gain; that means there is an advantage of using both osmotic agents (Bohuon, Collignan, Rios, & Raoult-Wack, 1998; Lerici, Pinnavaia, Dalla Rosa, & Bartolucci, 1985; Sereno, Moreira, & Martı́nez, 2001). The physical properties (density and viscosity) of aqueous solutions of sucrose and sodium chloride at 20 °C are available in handbooks (Lide, 1992; Weast, 1987) and for other temperatures scarce data can be found for sucrose (Misra & Varshni, 1961; Nabetani, Nakajima, Watanabe, Nakao, & Kimura, 1992) and for sodium chloride (Korosi & Fabuss, 1968; Sawamura, Yoshimura, Kutamura, & Taniguchi, 1992). Nevertheless, little data exists on the physical properties of the ternary aqueous solutions with both solutes in the range of interest (Bohuon, Le Maguer, & Raoult-Wack, 1997; Mulcahy & Steel, 1985). In addition, the correlation equations existing in the literature are in the polynomial form involving a great number of parameters (Brush, 1962; Hai-Lang & Shi-Jun, 1996).

The aim of this work is to report the kinematic viscosities and densities data of binary and ternary solutions of sodium chloride and sucrose at various concentrations and temperatures applicable to osmotic processing. A second aim is to propose a single equation to correlate density data and viscosity data with sugar and salt concentrations at various temperatures involving minimum number of parameters.

Section snippets

Materials and methods

Solutions were prepared using degassed distilled water and “commercial sugar” and “common salt” with purities >98% in saccharose and sodium chloride, respectively; both solutes were dried to constant mass at 105 °C. The solutions were prepared by mass using a Mettler AJ 150 balance with a precision of ±0.0001 g and were filtered before use.

Kinematic viscosities were determined in a Schott Geräte AVS 350 automatic Ubbelohde viscosimeter, using the experimental protocol described elsewhere (

Binary solutions

Table 1 shows experimental density values, $ρ (kg m^{−3})$ , of aqueous solutions of a single solute at 25 °C. These values were correlated with molal concentration of the solute, m, using the equation obtained by simplification of bibliographic polynomial equations (Bettin, Emmerich, Spieweck, & Toth, 1998) $ρ ρ_{W} =(1+am)^{b} =φ,$ where ρ_W is the water density at the same temperature, 997.2 $kg m^{−3}$ , and the values obtained of the fitting parameters a and b are listed in Table 2 for aqueous solutions with a single

Conclusions

Experimental data of kinematic viscosity and density, no available in the literature, were obtained and correlated with simple equations involving concentration and temperature for a wide range of experimental conditions. The results were successfully fitted and, in this way, the fittings allow to calculate the physical properties of these solutions of interest with a higher precision necessary for the study of osmotic processes. In this way, maximum deviations of ±0.5% using 4 parameters for

Acknowledgements

The authors acknowledge the partial support from the project PX120905PR of the Xunta de Galicia (Spain).

References (20)

P Bohuon et al.
Soaking process in ternary liquids: Experimental study of mass transport under natural and forced convection
Journal of Food Engineering
(1998)
H.N Lazarides et al.
Apparent mass diffusivities in fruits and vegetables tissues undergoing osmotic processing
Journal of Food Engineering
(1997)
A.M Sereno et al.
Mass transfer coefficients during osmotic dehydration of apple in single and combined aqueous solutions of sugar and salt
Journal of Food Engineering
(2001)
T.I Torok et al.
Viscosities, electrolytic conductivities, and volumetric properties of HCl–MCl_x–H₂O as a function of temperature up to high molal ionic strengths
Fluid Phase Equilibria
(1993)
H Bettin et al.
Density data for aqueous solutions of glucose, fructose and invert sugars
Zuckerindustrie
(1998)
P Bohuon et al.
Densities and viscosities of ternary systems of NaCl–sucrose–water from 283 to 303.15 K
Journal of Chemical Engineering Data
(1997)
S.G Brush
Theories of liquid viscosity
Chemical Reviews
(1962)
F Chenlo et al.
Viscosities of solutions of K₂SO₄, Na₂SO₄, KCl, NaCl, KNO₃, and NaNO₃ in (K₂CO₃+KHCO₃) and (Na₂CO₃+NaHCO₃) buffers
Journal of Chemical Engineering Data
(1997)
F Chenlo et al.
Viscosities of aqueous solutions of Fe₂(SO₄)₃ containing NaNO₃, KNO₃, NaBr, or KBr from 293.1 to 323.1 K
Journal of Chemical Engineering Data
(1998)
Z Hai-Lang et al.
Viscosity and density of water+sodium chloride+potassium chloride solutions at 298.15
Journal of Chemical Engineering Data
(1996)

There are more references available in the full text version of this article.

Cited by (94)

Modeling and experimental validation of the time-temperature profile, pectin methylesterase inactivation, and ascorbic acid degradation during the continuous flow microwave-assisted pasteurization of orange juice
2024, Food and Bioproducts Processing
This work evaluated the effect of microwave-assisted pasteurization on pectin methylesterase (PME) and ascorbic acid (AA) in orange juice (OJ) and proposed a model to predict the time-temperature profile of the process and consequent effect on inactivation and quality. Fresh OJ was pasteurized in a pilot-scale unit at four processing temperatures (70, 80, 90 and 100) °C, five holding times, using two heating systems (conventional and microwave). The experimental overall heat transfer coefficient was determined from the heat loads and correlated with Reynolds and Prandtl numbers. The best-adjusted correlation was used to predict the time-temperature profile considering a unidimensional mathematical model for flow and heat transfer. Predicted and experimental temperatures showed differences below 0.9 °C for all conditions. The model was able to predict PME inactivation and AA retention, indicating that microwave pasteurization of OJ can be as efficient as conventional heating on PME inactivation with less impact on AA.
Molecular dynamics study of sucrose aqueous solutions: From solution structure to transport coefficients
2022, Journal of Molecular Liquids
In this work, we study the applicability of the equilibrium molecular dynamics methods for the prediction of solution structure, equation of state and transport properties of sucrose aqueous solution for various concentrations and temperatures. The OPLS-AA force field with 1.14*CM1A charge corrections is used to describe the interactions in the model. We analyze the prediction power of the model against the experimental data and simulation results, obtained previously in CHARMM, OPLS-AA, GLYCAM06 and their modifications. The glycosidic linkage conformations of sucrose in solution are found. Their independence from the sugar concentration and the appearance of the conformation region at temperatures from 283 K to 308 K are observed. Sucrose solution densities are calculated for different sugar concentrations and temperatures. The obtained viscosities and sucrose diffusion coefficients match the experimental data at low sucrose concentrations, and diverge within 41% from the experiment as the concentration increases. The change of boundary condition in Stokes–Einstein formula is observed with an increase of the sucrose concentration above 40%.
A reactor engineering approach to describe bacterial inactivation during continuous UV-C light processing
2021, Innovative Food Science and Emerging Technologies
A reactor engineering approach was used to mathematically describe microbial inactivation during continuous UV-C light processing of liquid foods. The method was followed to analyze the survival curves of Lactobacillus rhamnosus inoculated into sucrose model solutions prepared at different concentrations (8, 10 and 12 g sucrose per 100 g of solution) and pH values (pH 3, 4.5 and 6), and further processed at two different residence times (4.85 and 29.9 min). The inactivation process was considered as an irreversible elemental reaction of unknown order occurring in a continuous stirred tank reactor. The proposed model was expressed in terms of the logarithmic reduction in microbial population and its straight-line form allowed the easy estimation of the inactivation rate constant and reaction order. Results indicated that inactivation of L. rhamnosus followed a variable order kinetic, moving from a first-order rate during unsteady-state operation to a near zero-order inactivation when steady-state operation was reached. Steady-state was reached faster (0.48 ± 0.11 min⁻¹ vs. 0.37 ± 0.7 min⁻¹, p < 0.05) and with a higher steady-state log reduction (5.9 ± 0.2 vs. 5.4 ± 0.6 log CFU/mL, p < 0.05) in experiments conducted with the lowest residence time, UV-C dose and power density (4.85 min, 12.8 J/cm² and 6.6 J/cm³).
Progressive freeze concentration of whey protein–sucrose–salt mixtures
2021, Innovative Food Science and Emerging Technologies
Progressive freeze concentration of whey protein solutions is evaluated. Since solutions in industry are more complex, the effect of the addition of sodium chloride and sucrose on the inclusion behaviour is studied as well. Using a progressive freeze concentrator solutions of whey protein and mixtures of whey protein and/or sucrose and/or sodium chloride were freeze concentrated. At an initial concentration of 4%(w/w), whey proteins were not included in the ice fraction. At higher concentrations the inclusions are caused by the increase in viscosity in the boundary layer, impeding mass transfer. The addition of sucrose caused a similar effect. Presence of sodium chloride causes inclusions through the occurrence of a zone where the solution is locally super-cooled and leads to the formation of dendritic ice which encapsulates pockets of solution in the ice layer. Mixtures of both sucrose and sodium chloride gave no additive effect on solute inclusion but just a concurrent effect.
Approximation of dynamic membrane distillation processes applied to concentration of aqueous sucrose solutions
2021, Desalination
In this work, a method is presented for the approximation of dynamic processes. Dynamic inputs of membrane distillation can be approximated by a regression equation as several steady state steps after each other. A regression equation of the flux was developed based on a validated steady state model and a wide range of process parameters. The regression equation of the flux is then used to approximate a dynamic process. To test the approximation on a dynamic process, a new test setup was developed to provide quick changes to the temperatures or flow. It was found that the approximation corresponds well to the test results. While this paper only approximates the flux, the method presented in this paper can also be used to approximate other variables. The presented method is also applied to the concentration of aqueous sucrose solutions with an AGMD module with oleophobic and hydrophobic properties. Three semi batch tests were done. The approximation corresponds well to the test results. A maximum Brix concentration of 56.9 was reached in the tests.
Aqueous viscosity of carbohydrates: Experimental data, activity coefficient modeling, and prediction with artificial neural network-molecular descriptors
2021, Journal of Molecular Liquids
Food waste is a rich source of carbohydrates. This material can be reprocessed in order to produce purified compounds or other materials with high added value. The implementation of processes that enable this transformation depends on kinematic viscosity data and robust mathematical modeling. In order to meet part of this demand, the objective of this work was to study the kinematic viscosity of binary and ternary solutions involving sucrose, sorbitol, xylose and xylitol in the temperature range between 303.15 K and 363.15 K at concentrations of 0.5 mol‧kg⁻¹ to 3.0 mol‧kg⁻¹. In the correlation of experimental data, the Eyring equation was associated to the Margules, van Laar, Wilson and NRTL models. In the simulation, an artificial neural network associated with molecular descriptors was developed. The experimental results showed to be dependent on the number of OH groups present in the sugar. The mathematical modeling proved to be efficient in the treatment of the experimental data, with the NRTL model being the one with the best performance. Artificial neural networks were satisfactory in the simulation of the data, with the 7–7–5-1 architecture being the one with the best data prediction capacity.

View all citing articles on Scopus

View full text

Viscosities of aqueous solutions of sucrose and sodium chloride of interest in osmotic dehydration processes

Abstract

Introduction

Section snippets

Materials and methods

Binary solutions

Conclusions

Acknowledgements

Journal of Food Engineering

Journal of Food Engineering

Journal of Food Engineering

Fluid Phase Equilibria

Density data for aqueous solutions of glucose, fructose and invert sugars

Zuckerindustrie

Densities and viscosities of ternary systems of NaCl–sucrose–water from 283 to 303.15 K

Journal of Chemical Engineering Data

Theories of liquid viscosity

Chemical Reviews

Viscosities of solutions of K2SO4, Na2SO4, KCl, NaCl, KNO3, and NaNO3 in (K2CO3+KHCO3) and (Na2CO3+NaHCO3) buffers

Journal of Chemical Engineering Data

Viscosities of aqueous solutions of Fe2(SO4)3 containing NaNO3, KNO3, NaBr, or KBr from 293.1 to 323.1 K

Journal of Chemical Engineering Data

Viscosity and density of water+sodium chloride+potassium chloride solutions at 298.15

Journal of Chemical Engineering Data

Viscosities of solutions of K₂SO₄, Na₂SO₄, KCl, NaCl, KNO₃, and NaNO₃ in (K₂CO₃+KHCO₃) and (Na₂CO₃+NaHCO₃) buffers

Viscosities of aqueous solutions of Fe₂(SO₄)₃ containing NaNO₃, KNO₃, NaBr, or KBr from 293.1 to 323.1 K