Effective Diffusion Coefficients during Osmotic Dehydration of Vegetables with Different Initial Porosity

2006 ◽  
Vol 258-260 ◽  
pp. 575-585
Author(s):  
Luis Mayor ◽  
Ramón Moreira ◽  
Francisco Chenlo ◽  
Alberto M. Sereno
Keyword(s):  
Mass Transfer ◽  
Osmotic Dehydration ◽  
Effective Diffusion ◽  
Food Material ◽  
Transfer Rates ◽  
Sodium Chloride Solutions ◽  
Effective Coefficients ◽  
Sucrose Solutions ◽  
Diffusional Model ◽  
Transfer Mechanisms

Chesnut and pumpkin fruits were dehydrated with osmotic solutions of sucrose and NaCl at 25°C. These food materials have different structure, composition and porosity. Water loss and solids gain kinetics were experimentally determined and modeled using a diffusional model. In spite of the several mass transfer mechanisms taking place along with diffusion during osmotic dehydration, the modeling was satisfactory and involved effective coefficients of diffusion useful to quantify the different mass transfer fluxes. Water and sucrose transfer rates during osmotic dehydration with sucrose solutions are independent on the initial food material characteristics; however they seem to be related with the permeability of these components to a sucrose layer formed in the surface of the samples. In the case of osmotic dehydration with sodium chloride solutions, the coefficients of diffusion show a dependence on food material characteristic and higher values of these coefficients for pumpkin (more porous material) were found.

Mass Transfer Analysis during Osmotic Dehydration of Eggplant Using Binary Solutions of Sucrose and Sodium Chloride

2008 ◽  
Vol 273-276 ◽  
pp. 413-418
Author(s):  
Ramón Moreira ◽  
Francisco Chenlo ◽  
N. Vallejo ◽  
Lionel Gerbet
Keyword(s):  
Mass Transfer ◽  
Sodium Chloride ◽  
Water Loss ◽  
Osmotic Dehydration ◽  
Chloride Solutions ◽  
Binary Solutions ◽  
Sodium Chloride Solutions ◽  
Effective Coefficients ◽  
Diffusional Model

Osmotic dehydration of eggplant slices in sucrose and sodium chloride solutions at different solution concentrations, stirring levels and time of process is studied. Water loss and solids gain kinetics were experimentally determined and modelled using a diffusional model and equilibrium values were predicted by means of Azuara model. Modelling was satisfactory and involved effective coefficients of diffusion useful to quantify the different mass transfer fluxes.

Mass Transfer Analysis during Osmotic Dehydration of Pumpkin Fruits Using Binary and Ternary Aqueous Solutions of Sucrose and Sodium Chloride

2006 ◽  
Vol 258-260 ◽  
pp. 213-218
Author(s):  
Luis Mayor ◽  
Ramón Moreira ◽  
Francisco Chenlo ◽  
Alberto M. Sereno
Keyword(s):  
Mass Transfer ◽  
Sodium Chloride ◽  
Aqueous Solutions ◽  
Osmotic Dehydration ◽  
Effective Diffusion ◽  
Effective Diffusivity ◽  
Ternary Systems ◽  
Solute Concentration ◽  
Solute Acquisition ◽  
Diffusional Model

Osmotic dehydration experiments of pumpkin with binary aqueous solutions of sucrose, sodium chloride and ternary solutions with both solutes at 298 K were carried out. Weight reduction, water loss and solute acquisition kinetics were determined. Experimental data were fitted employing a diffusional model considering samples as spheres and the external resistance to the mass transfer negligible. The model gave as parameter of fitting an effective diffusion coefficient for each component transferred (water, sucrose and sodium chloride) for each experimental condition assayed. Correlations between the effective diffusivity and solute concentration were established for binary and ternary systems.

scholarly journals Mathematical modelling of the osmotic dehydration of physalis

2018 ◽  
Vol 21 (0) ◽  
Author(s):  
Fernanda Rosa Assis ◽  
Rui Manuel Santos Costa de Morais ◽  
Alcina Maria Miranda Bernardo de Morais
Keyword(s):  
Mass Transfer ◽  
Atmospheric Pressure ◽  
Osmotic Dehydration ◽  
Mass Ratio ◽  
Promising Alternative ◽  
Sucrose Solutions ◽  
Mass Transfer Kinetics ◽  
Osmotic Agent ◽  
Effective Diffusivities ◽  
Best Fit

Abstract Physalis was osmotically dehydrated with 60 °Bx sucrose or sorbitol solutions at 60 °C and with a mass ratio of sample to solution of 1:4, at atmospheric pressure or under vacuum at 150 mbar. The Crank’s, Peleg’s and Page’s models were tested to describe the mass transfer kinetics for water loss (WL) and solids gain (SG). The effective diffusivities of both water and solute were around 10-11 m2 s-1 under all conditions. Peleg’s model presented the best fit. The use of sorbitol as the osmotic agent resulted in an increase in the WL rate. In experiments with sucrose solutions, a higher WL was obtained under vacuum than at atmospheric pressure. The SG was particularly low during osmotic dehydration. Thus, the use of sorbitol as the osmotic agent was shown to be a promising alternative to sucrose.

Water Diffusion in Intermittent Solar Drying of Mangaba (Hancornia speciosa)

2020 ◽  
Vol 399 ◽  
pp. 196-201
Author(s):  
Acácia Lima Silva ◽  
Gabriel Francisco Silva ◽  
Luciano Fernandes Monteiro ◽  
Álvaro Silva Lima ◽  
Odelsia Leonor Sánchez Alsina
Keyword(s):  
Sucrose Solution ◽  
Osmotic Dehydration ◽  
Effective Diffusion ◽  
Spherical Geometry ◽  
Water Diffusion ◽  
Average Radius ◽  
Solar Drying ◽  
External Resistance ◽  
Diffusional Model ◽  
Hancornia Speciosa

The present work has the objective to study the water diffusion in the process of intermittent solar drying of mangabas. Osmotic dehydration (OD) pretreatment was performed in sucrose solution and the drying took place in a direct solar dryer with the fruits arranged in stainless steel screens, temperatures varying between 30 and 45°C along the day with peaks of 70°C. The period of intermittence was approximately 16 h reaching equilibrium after 6 days. The diffusional model based on the second Fick’s law was proposed for each of the daily drying periods of 360 minutes, considered that the process is controlled by internal diffusion, negligible external resistance, spherical geometry, shrinkage based on the average radius. The coefficients of effective diffusion (Def) obtained by using 4 terms of the infinite series, present values of Def ranging from 0.2 to 3.30x10-10 m2/s with R2≥ 0.868 and average relative deviations MRD≤10-2.

Effect of Temperature and Volume Changes on Effective Diffusivities of Sucrose and NaCl during Osmotic Dehydration of Vegetable Tissue

2008 ◽  
Vol 273-276 ◽  
pp. 138-143 ◽  
Author(s):  
Luis Mayor ◽  
João M.P.Q. Delgado ◽  
M. Vázquez da Silva ◽  
Alberto M. Sereno ◽  
Maria P. Gonçalves
Keyword(s):  
Cucurbita Pepo ◽  
Osmotic Dehydration ◽  
Effective Diffusion ◽  
Effect Of Temperature ◽  
Volume Changes ◽  
External Resistance ◽  
Effective Diffusion Coefficients ◽  
Different Temperatures ◽  
Effective Diffusivities ◽  
Diffusional Model

Osmotic dehydration of pumpkin (Cucurbita pepo, L.) fruits was carried out with binary solutions of sucrose and NaCl at different temperatures and solute concentrations. Water loss and solids gain kinetics were experimentally determined and fitted using a diffusional model. Pumpkins samples were considered as finite cylinders and the analytical solution of the unsteady diffusion equation was used considering the external resistance to the mass transfer negligible. The influence of shrinkage and temperature on the effective diffusion coefficients was also assessed in this work.

scholarly journals Numerical Calculation of the Diffusion Process in Multicomponent Hydrocarbon Gas Mixtures

2021 ◽  
Vol 15 ◽  
pp. 61-68
Author(s):  
Beketayeva Meruyert
Keyword(s):  
Mass Transfer ◽  
Diffusion Processes ◽  
Effective Diffusion ◽  
Mass Transfer Process ◽  
Multicomponent Diffusion ◽  
Gas Mixtures ◽  
Production Operation ◽  
Gaseous Fuels ◽  
Effective Coefficients ◽  
Hydrocarbon Gas

Knowledge of the laws of diffusion is necessary in the description, design and calculation of the mass transfer process in the production, operation and transportation of gaseous fuels. In this article, the calculation of diffusion processes for five natural hydrocarbon gas mixtures into the air was carried out. The effective diffusion coefficients and matrix coefficients of multicomponent diffusion were determined. Also the advantages of using effective coefficients in the description of mass transfer were shown.

Freeze/Thaw Effects on Mass Transfer Rates during Osmotic Dehydration

1995 ◽  
Vol 60 (4) ◽  
pp. 826-828 ◽  
Author(s):  
HARRIS N. LAZARIDES ◽  
NIKOLAOS E. MAVROUDIS
Keyword(s):  
Mass Transfer ◽  
Osmotic Dehydration ◽  
Transfer Rates ◽  
Freeze Thaw
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