Mass Transfer In Osmotic Dehydration Research Articles

Osmotic dehydration of berries: study of mass transfer parameters

Osmotic dehydration, due to its advantages related to energy and quality, is gaining popularity as an additional stage of processing in the chain of complex processing of products. As a rule, osmotic dehydration is a slow process, so there is a need for additional methods to increase mass transfer without adversely affecting the quality of the product. This has provided the necessary motivation for many recent achievements in the field. Minimal processing methods, such as osmodehydration, find a significant place in the processing industry to increase the shelf life of fruit and berry raw materials. The overall efficiency of the process is determined by the process parameters affecting the phenomenon of mass transfer. Therefore, in this work the parameters of mass transfer in osmotic dehydration of berry raw materials: strawberry, raspberry, blackcurrant, BlackBerry are studied. The process of mass transfer has been modeled effectively, as evidenced by the results obtained. Berries, previously dehydrated at 70°Brix solution of sucrose, have the cryoscopy temperature lower (-1.7°C)–(-4.8°C), dehydrated at 60°Brix solution of sucrose from (-1.1°C) to (-2,6°C).The number of crystallized water in berries, dehydrated in 60°Brix solution of sucrose made up from 8.6–10.1 %, and in 70°Brix solution from a 13.9–12.9 %.The amount of frozen water in berries, dehydrated 70 ° Brix sucrose solution from 7.5–40.4%, dehydrated 60°Brix sucrose solution from 2.3–10.1%. Reducing the activity of water in berries treated with 70°Brix solution was 2.8–0.8 %, 60°Brix sucrose solution from 1.4–0.3%. The obtained data show that due to osmotic dehydration of berries with a solution of sucrose, followed by freezing, the activity of water decreases, which allows extending the shelf life and limits the access of microorganisms to growth in the environment.

Mass Transfer in Osmotic Dehydration of Food Products: Comparison Between Mathematical Models

Osmotic dehydration (OD) is a method to partially reduce water of fruits, vegetables, meat or fish aiming to increase the shelf life or as a pre-treatment in the processing of dehydrated foods. The aim of this work is to present the models most used in mathematical modelling of experimental data obtained from the OD processes, correlating the water loss and solid gain of the food product with process variables, and to perform a comparative and critical analyses of the different models and ability to fit data. The osmotic solution concentration, the temperature, the level of agitation and the geometry of the product are some of the operating parameters that will be mainly focused. Azuara’s, Peleg’s, Page’s, the Penetration, Magee’s, Weibull’s, Toupin et al.’s, Marcotte et al.’s, the Hydrodynamic mechanism, Spiazzi and Mascheroni’s, Segui et al.’s, Crank’s, Hough et al.’s were the models approached. These were classified into empirical and semi-empirical, phenomenological and mechanistic, and the advantages and disadvantages were presented. An extensive list of applications of the different models to the osmotic dehydration, in variable ranges of operating conditions, of fruits, vegetables, meat and fish is provided in this work. Furthermore, equivalences between parameters of different models were established, based on the affinity of the functions used in the equations of the models, these equivalences allowing a better understanding of the adequacy of the different models to fit the same experimental data. A decision tree is provided in order to allow the selection of the most adequate model(s) to fit and predict experimental data from OD processes. All this information could assist and be helpful to researchers in the choice of the most adequate model(s) to fit experimental data, as well as to predict the water loss and solid gain of food products during OD processes.

Osmotic Dehydration Dynamic of Common Carp (Cyprinus carpio) Fillets Using Binary and Ternary Solutions

In this work, water activity (aw), moisture loss, and salt uptake as mass transfer in osmotic dehydration (OD) of Cyprinus carpio fillets were analyzed. Two highly concentrated solutions were used for the OD: binary (NaCl-water) and ternary (NaCl-sucrose-water) solutions at 20°C. Both solutions had the same NaCl concentration, but the second also had sucrose (2:1) which improved water loss and reduced NaCl gain. Among the OD models analyzed, Peleg's equation presented the best fit with the ternary solution (R2 > 0.900), while the Zugarramurdi and Lupín did so for the binary solution treatment (R2 > 0.950). Page's model presented good fit for water release in both cases (R2 > 0.950).

Osmotic dehydration of some agro-food tissue pre-treated by pulsed electric field: Impact of impeller’s Reynolds number on mass transfer and color

Tissues of apple, carrot and banana were pre-treated by pulsed electric field (PEF) and subsequently osmotically dehydrated in an agitated flask at ambient temperature using a 65% sucrose solution as osmotic medium. The effect of stirring intensity was investigated through water loss (WL) and solid gain (SG). Changes in product color were also considered to analyze the impact of the treatment. The impeller’s Reynolds number was used to quantify the agitation. The Reynolds number remained inferior to 300 thus displaying laminar flow regime. Water loss (WL) and solid gain (SG) increase with the increase of Reynolds number. Mass transfer in osmotic dehydration of all three test particles has been studied on the basis of a two-exponential kinetic model. Then, mass transfer coefficients were related to the agitation intensity. This paper shows that the proposed empirical model is able to describe mass transfer phenomena in osmotic dehydration of these tissues. It is also shown that a higher agitation intensity improves both the kinetics of water loss and solid gain.

Mathematical modeling of moisture and solute diffusion in the cylindrical green bean during osmotic dehydration in salt solution

In this study, mass transfer during osmotic dehydration of cylindrical cut green beans in salt solution was investigated. The osmotic solution concentrations used were 10%, 20% and 26.5% (w/w) NaCl, osmotic solution temperatures used were 30 °C, 40 °C and 50 °C, the solution-to-green bean mass ratio was more than 20:1 (w/w) and the process duration varied from 0 to 6 hr. A two-parameter mathematical model developed by Azuara et al. (1992) was used for describing the mass transfer in osmotic dehydration of green bean samples and estimation of the final equilibrium moisture loss and solid gain. Effective radial diffusivity of moisture as well as solute was estimated using the analytical solution of Fick's second law of diffusion in the cylindrical coordinates. For above conditions of osmotic dehydration, moisture and salt effective diffusivities were found to be in the range of 1.776 × 10 −10–2.707 × 10 −10 m 2/s and 1.126 × 10 −10–1.667 × 10 −10 m 2/s, respectively. Moisture and solute distributions as a function of time and location in the radial direction were plotted by using the estimated equilibrium moisture and solute concentrations and also moisture and solute diffusivities.

Modelling ofMass Transfer in Osmotic Dehydration ofAonla Slices

Modelling ofMass Transfer in Osmotic Dehydration ofAonla Slices

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.

A Comparison of Some Mathematical Models Used for the Prediction of Mass Transfer Kinetics in Osmotic Dehydration of Fruits

Mass transfer in osmotic dehydration of fruits at atmospheric pressure has been modeled either by a phenomenological approach using Crank's model (which is a Fick's law solution) or empirically, using models developed from polynomial equations, mass balances, or relations between process variables (i.e., Magee's, Azuara's, and Page's models). For all of these models, experimental data are required to determine the values of their adjustable parameters for specific processing conditions. From a wide variety of published data, the parameters for moisture loss (ML) and solid gain (SG) were calculated for the above-mentioned models, and a comparison of their correlation capability was made. Azuara's and Page's models yield better correlations (with mean absolute errors less than 1.26% for ML and 0.46% for SG) than Magee's and Crank's models (with mean absolute errors of up to 2.98 and 1.68% for ML and SG, respectively).

Mathematical modeling of mass transfer in osmotic dehydration of onion slices

The study on osmotic dehydration of onion slices was carried out in order to remove the moisture prior to the further mechanical drying. Three salt concentration levels (5%, 12.5% and 20%), three temperature levels of osmotic solution (28 °C, 43 °C and 58 °C) and the observations on weight loss and solid gain were taken at an interval of 5 min up to first half an hour followed by interval of 10 min for next 1 h. The sample to solution ratio of 1:5, agitation of 100 shakes per minute, sample thickness of 4 mm and 0.2% potassium metabisulphite mixed with osmotic solution were used for the study. A two-parameter mathematical model developed by Azuara et al. was used for describing the mass transfer in osmotic dehydration of onions slices. The effect of time on mass transfer kinetics was investigated and the constants of two-parameter model and final equilibrium points for moisture loss as well as solid gain were found. The effect of solution concentration and solution temperature was also studied and it was found that equilibrium moisture loss and solid gain are related to solution concentration and solution temperature logarithmically. The optimum conditions of osmotic dehydration for further drying were found to be 20% salt concentration, 28 °C solution temperature and 1-h of osmosis.

A study of the mass transfer in osmotic dehydration of coated potato cubes

This study investigated the coupling of edible coatings with osmotic dehydration of potato cubes under various process conditions. Solutions of 1% sodium alginate and 2% low methoxyl pectinate (LMP, degree of esterification: 31.5%) were chosen as the coating materials and NaCl was used as the osmotic agent to study the mass transfer behavior during osmotic dehydration of potato tissues. Potatoes were cut into cubes of 1 cm 3 and coated with the coating materials. Calcium chloride solution of 1% or 2% was used as the cross-linking agent. Salt concentration of 10%, 14% and 18% and temperature of 25, 40 and 55 °C were used as the process variables to investigate the kinetics of water loss and salt uptake. Modeling of the mass diffusion and its kinetics were carried out to better understand the mass transport phenomena in potatoes with coatings and to determine the efficacy of the coupled system. Mass transfer kinetics was modeled by using Peleg’s proposed equation and the effect of process variables on the model parameters was studied. Diffusivities of both water and solute were evaluated by using Crank’s analytical solution to Fick’s second law. These two models could well describe how the considered variables influenced the mass diffusion and kinetic rate constants during the osmotic dehydration of both non-coated and coated potatoes.

Development in the Combined Treatment of Coating and Osmotic Dehydration of Food - A Review

Osmotic dehydration is gaining considerable attention as a minimal processing method because of its advantages such as saving energy to compliment drying process, better control of flavor loss and tissue damage problems and improved retention of color and nutritional constituents. The problems of flavor loss, tissue damage, color degradation and nutritional loss are present in traditional hot air drying due to the high temperature involved. However, except for candied food, large penetration of solute into the food becomes a major problem in osmotic dehydration. The application of a coating on food prior to osmotic dehydration is a promising solution to alleviate the large solute intake problem. Edible coatings serve as a barrier to limit the penetration of solute without having an adverse effect on water removal. This paper focuses on this combined technology and its potentials. The effects of edible coatings on both water and solute mass transfer in osmotic dehydration are reviewed. Suitable coating materials and their applicable concentration range for osmotic dehydration of food are evaluated. Mathematical models describing the mass transfer in osmotically dehydrated food with coatings are also reviewed.

Osmotic dehydration of tilapia fillets in limited volume of ternary solutions

In this study, water activity, moisture content reduction and solute uptake kinetics as well as mass transfer in osmotic dehydration of tilapia (Oreochromis niloticus) fillets were studied, using limited volumes (solution/fillet ratio: 4/1) of ternary solutions (salt–sugar–water) at different initial sucrose (0–100 g in 100 g of water) and salt (0–35.14 g in 100 g of water) concentrations at 20 °C. The multicomponent effective diffusion coefficients were calculated by fitting the experimental values to analytical solution of mass transfer equations with a limited solution/fillet ratio. Previously, the effective diffusion coefficients of salt and sugar in tilapia muscle were calculated using a binary system. A very good fit between the mathematical model and experimental values was observed. The binary coefficients obtained were: for sodium chloride, D 11, 0.91×10 −9 m 2 s −1 and sucrose, D 22, 0.22×10 −9 m 2 s −1, and the calculated cross-term coefficients, D 12 and D 21, were −0.12×10 −9 and 0.06×10 −9 m 2 s −1, respectively.

POSSIBILITY OF USING PSEUDO-DIFFUSION APPROACH TO MODEL MASS TRANSFER IN OSMOTIC DEHYDRATION

The possibility of using a pseudo-diffusion approach to model mass transfer in osmotic dehydration wasinvestigated through the analysis of mass change and effective diffusivity. The mass change was obtained using a computer simulation model and then the effective diffusivity was calculated according to the mass change. It was shown that the mass transfer in osmotic dehydration was not a unique function of Fourier number for mass transfer as in pure diffusion, but depended on the diffusivity of solute and dimension of tissue. In addition, the effective diffusivity used in this pseudo-diffusion approach varied non-linearly with processing time. Therefore the model developed through this pseudo-diffusion approach had no predictive ability unless the variation of the effective diffusivity could be estimated.

ANALYSIS OF MASS TRANSFER IN OSMOTIC DEHYDRATION BASED ON PROFILES OF CONCENTRATION, SHRINKAGE, TRANSMEMBRANE FLUX AND BULK FLOW VELOCITY IN THE DOMAIN OF TIME AND SPACE

ABSTRACTAn analysis of mass transfer mechanisms in osmotic dehydration was carried out by examining the profiles of concentration, shrinkage, transmembrane flux and bulk flow velocity in the domain of time and space. The profiles were obtained through simulations using a computer simulation model that described mass transfer in osmotic dehydration based on cellular structure. It was shown that bulk flow was the main resistance for solute penetration, and the magnitude of bulk flow was affected not only by the transmembrane flux, but by internal cellular structure changes. Since bulk flow often played an important role in mass transfer during osmotic dehydration, precautions should be taken when interpreting mass transfer in osmotic dehydration using a simple pure diffusion theory.

Application of osmotic treatment in tomato processing—effect of skin treatments on mass transfer in osmotic dehydration of tomatoes

Osmotic dehydration can be a method to minimize negative modifications of fresh food components during processing. Cut tomatoes are poorly suited to osmotic dehydration because of their heterogeneous texture and potential excessive loss of liquid components. Moreover, the limiting stage of whole tomato fruit dehydration is water movement through the skin. Skin treatments followed by osmotic dehydration of whole tomatoes was tested. A NaOH solution mixed with ethyl oleate had less tomato fruit peel damage and higher water removal, than a NaOH solution by itself. The NaOH solution was more effective than a HCl solution in water removal. Chemical skin treatment of 7–8% NaOH solution resulted in undesirable tomato texture softening at room temperature. Physical skin puncturing treatment had higher water removal potential than chemical skin treatments. Physical treatment of tomato skin did not create waste material. A kinetic study was done to analyze the relationship between skin permeability and the mass transfer property.

Mathematical modelling and simulation of mass transfer in osmotic dehydration processes. Part II: Simulation and model verification

In Part I of the present communication, a mathematical model describing mass transfer in osmotic dehydration was proposed. This second part presents a computer simulation procedure used to solve the model equations to obtain concentration profiles in tissue subjected to osmotic dehydration. In the simulation, a one-dimensional finite element method was used as a numerical tool. The model was validated using experimental data obtained in osmotic dehydration of potato tubers and a good agreement was obtained. A sensitivity analysis and parametric study of the model will be presented in Part III of this series of communications.

Osmotic Dehydration: An Analysis of Fluxes and Shrinkage in Cellular Structure

A comprehensive analysis of fluxes and shrinkage in cellular structure immersed in osmotic solution was carried out. A relation between shrinking velocity and bulk flow velocity (volume average velocity) was developed for a shrinking body through volume change. Equations were derived to relate fluxes based on stationary frame and shrinking velocity frame, as well as based on the total interface area and true flow channel in cellular tissue. Computer simulations were carried out to show the trend and relative magnitude of diffusion, bulk flow and net fluxes of potato tissue slice immersed in 0.535 kmol/m3 mannitol solution. It was shown that the net volume flux ratio of water to mannitol was about 60 most of the time, but could be as high as 450 at the beginning of the process. In addition, the bulk flow transported about 90% of water removed in osmotic dehydration and washed back about 60% of mannitol penetrating by diffusion. Therefore the bulk flow should be considered in describing mass transfer in osmotic dehydration.

Mass Transfer in Mixed Solute Osmotic Dehydration of Apple Rings

Development and verification of a model for mass transfer in osmotic dehydration of apple rings in mixed solute osmotic media is described. ‘Red Delicious’ apple rings were osmotically dehydrated in sucrose-sodium chloride solutions of 50% total solids-50% water. The sodium chloride concentration was varied at 0, 2.5, 5 and 10% by weight. The temperatures used were 20, 30, and 50° C, and contact times were 0, 1, 2, 3, and 4 h. Moisture loss (Y) was calculated as a fraction of original moisture in apple rings, and the combined solute-gain was expressed as an “equivalent molality”, C, of sucrose and sodium chloride in the liquid phase of apple rings. Both Y and C were modeled as functions of osmotic solution composition, temperature and time of contact. An empirical equation was developed to establish a relationship between the instantaneous mass fractions of sucrose and sodium chloride in apple rings. The above three equations and a fourth equation derived from mass balance on total solids originally present in apple rings, were solved simultaneously to give the ratio of instantaneous to original total mass of apple rings (mq/m0) and instantaneous mass fractions of sucrose (w2), sodium chloride (w1), and water (w4) in the apple rings. Knowing mq/m0, w1, w2, and w4, and from the knowledge of total solids originally present in the material, one can calculate the moisture loss and individual solutes-gain during osmotic contacting.