Osmotic Dehydration Kinetics Research Articles

Modelling of mass transfer kinetics of sapota (<i>Achraszapota</i>) in ternary solutions of sugar and calcium salt during osmotic dehydration

The mass transfer kinetics of sapota in ternary solution was studied at an optimised condition derived using the Box-Behnken design of response surface methodology (RSM). The optimised conditions were found for minimising solid gain and water activity and maximising water loss, weight reduction and overall acceptability. The osmotic dehydration kinetics data were fitted in viz. the Magee model, Page's model and Azuara model. In a comparative study of mass transfer kinetics of sapota between three models viz. the Magee model, Page's model and Azuara model. Page's model was found to fit more effectively to Sapota, for the prediction of water loss and solid gain kinetics during the osmotic dehydration.The simplified solution of Fick's second law of diffusion for a slab geometry was used to calculate the average values of apparent diffusion coefficient (Deff), namely 4.49 × 10−08 m2/s for WL and 4.27 × 10−08 m2/s for SG.

Effects of liquid smoke infusion on osmotic dehydration kinetics and microstructural characteristics of apple cubes

The influence of the addition of Refined Liquid Smoke (RLS) (1% w/w) to a sugar-based Osmotic Solution (OS) (42 °Brix) on the osmotic dehydration (OD) kinetics and microstructure of apple cubes was evaluated. Cubes of 10 mm were cut from peeled apples and subjected to OD at the incubation temperature of 50 °C and over a range of OD duration (5–240 min). Influence of addition of RLS was evaluated for selected OD kinetic variables: solid gain (SG), water loss (WL), dry matter (DM), soluble solid content (SSC), and moisture content. Results showed that addition of RLS significantly increased SG, DM, and SSC in apple cubes compared to pure sugar solution-based OD. As a result of RLS addition, the sugar concentration in apple cubes increased from 9.90 °Brix to 33.8 °Brix whereas it was 31.02 °Brix for the pure sugar solution-based OD. Further kinetic analysis showed that the effective diffusion coefficient for SG was same (4.40 × 10−10 m2/s) irrespective of the addition of RLS; however, the effective diffusion coefficients for WL were different (2.94 × 10−10 m2/s for pure sugar-based OD and 4.40 × 10−10 m2/s for RLS-added OD). Microstructural visualization of the dried apples revealed that the addition of the RLS might have prevented the collapse of cell wall up to the first hour of OD.

Apple osmotic dehydration described by three-dimensional numerical solution of the diffusion equation

ABSTRACTIn the present study, experimental data of osmotic dehydration kinetics of apple, cut into slices with parallelepiped shape, were simulated using two types of diffusion models. Model 1 considers the constant values of mass diffusivities and volume of the slices. Model 2, on the other hand, considers variable mass diffusivities and also the shrinkage of the product. The numerical solution of the three-dimensional diffusion equation in Cartesian coordinates was obtained through the finite volume method, with a fully implicit formulation and boundary condition of the first kind. Process parameters were determined by optimization using the experimental data sets, through the minimization of an objective function, called χ2. The results of the osmotic dehydration kinetics were compatible with those of other studies found in the literature. Process temperature and osmotic solution concentration had influence on the phenomenon, but temperature was preponderant. A study was conducted on water and sucrose distribution during the osmotic dehydration. The results obtained through the mathematical model that considered the variable diffusivity and shrinkage showed greater adequacy to the experimental data.

Osmotic dehydration kinetics of oyster mushroom

This research was carried out to study the effect of osmotic dehydration behavior of oyster mushroom. The effect of solution concentration, immersion time and temperature on mass transfer parameters were observed during osmotic dehydration of oyster mushroom at three different temperatures −12, 27 and 45°C. A number of process parameters on osmotic dehydration such as water loss (WL), solid gain (SG), and normalized solid content (NSC) were investigated. Results showed that increase in salt concentration and immersion time resulted in %WL, %SG and NSC. The highest NSC (4.09 g solids/100g of initial weight of sample) was achieved for product osmosed in 25% salt solution for 6 hr immersion time. The pseudo diffusion coefficient, k was determined by using Fick’s First Law of diffusion equation. Plotting k values against inverse absolute temperature an Arrhenius type relationship was developed from which the calculated activation energy values of 1.8 and 3.64 kcal/gm-mole were obtained for 20% and 15% salt solution respectively.

Description of Osmotic Dehydration of Melon Cubes using a Three-dimensional Diffusion Model: An Algorithm to Determine the Effective Diffusivity

Abstract This paper aims to study the transient mass diffusion during the osmotic dehydration of melon cubes, using the analytical solution of the diffusion equation with boundary condition of the first kind. Two techniques are used to determine the effective mass diffusivity, using experimental data. In technique 1, available in the literature, the domain of the effective diffusivity is scanned from a value close to zero, until the minimum value of the objective function (Chi-square) is determined. Technique 2, proposed in this paper, uses an algorithm based on the optimal removal of experimental points, until obtaining the objective function with a minimum value, allowing to determine the optimal value for the effective mass diffusivity. The obtained values for diffusivity and statistical indicators revealed that both techniques generate equivalent results and allowed to satisfactorily describe the kinetics of osmotic dehydration of melon cubes. However, technique 2, proposed in this paper, is much faster than technique 1, in the determination of effective mass diffusivity, for all analyzed sets of experimental data.

Effect of microwave-vacuum, ultrasonication, and freezing on mass transfer kinetics and diffusivity during osmotic dehydration of cranberries

ABSTRACTThe objectives of this study were (i) to evaluate moisture loss (ML), solids gain (SG), moisture loss rate (d(ML)/dt), solids gain rate (d(SG)/dt), effective moisture diffusivity (DeM), and effective solids diffusivity (DeS) during osmotic dehydration (OD), ultrasound-assisted osmotic dehydration (UA-OD), and osmotic dehydration of whole cranberries, preceded by microwave-vacuum pretreatment (MV + OD) or freezing/thawing treatment (F + OD ) and (ii) to use a mathematical model to predict moisture content ML∞ and solids content SG∞ in equilibrium state and the distribution of moisture and sucrose in whole cranberries during dehydration. Microwave-vacuum and OD treatments produced cranberries with the highest values of ML and SG (39.7 and 8.4 g 100 g fresh fruit−1, respectively), d(ML)/dt and d(SG)/dt (76.9 and 8.5 h−1, respectively), DeM and DeS (6.1 and 3.7 × 10−10 m2 s−1, respectively). Azuara’s and Peleg’s models adequately described the OD kinetics of whole cranberries in terms of ML and SG. The results indicate that the equilibrium values of ML∞ and SG∞ were not reached under the conditions specified in the present study.

Combined osmotic dehydration and drying process of pirarucu (Arapaima gigas) fillets

The osmotic dehydration (OD) and complementary drying of pirarucu (Arapaima gigas) fillets were studied. Pieces of the dorsal portion of pirarucu (60mm×20mm×10mm) underwent OD in a binary solution (NaCl-water) with the application of vacuum pulse following a central rotatable composite design. The effect of the following process variables was assessed: temperature (20-40°C), osmotic solution concentration (15-25% NaCl), and vacuum pulse pressure (7-101kPa) on water loss (WL), solid gain (SG), and water activity (aw). OD kinetics was obtained and the Peleg model was fitted to WL and SG data. The osmotically dehydrated pirarucu was dried (40-70°C) in a fixed-bed dryer and mathematical models were fitted to the drying data. The optimal operational condition for the OD process was 35°C, solution with 25% NaCl, and atmospheric pressure, which yielded WL of 14.87±1.46%, SG of 8.56±0.45%, and aw of 0.87±0.02. The Peleg model efficiently predicted the WL and SG kinetics. The increase in the water loss in drying was more evident at low temperatures (40-50°C) with effective diffusivity ranging from 10.85×10-9 to 12.30×10-9 m2/s. The Midilli and Page models efficiently predicted the drying kinetics.

Effects of calcium lactate and ascorbic acid on osmotic dehydration kinetics and metabolic profile of apples

The influence of the addition of calcium lactate (CaLac) and ascorbic acid (AA) to sucrose (Suc) osmotic solutions on osmotic dehydration kinetics and endogenous metabolic heat production of apple tissue was evaluated. Our research goal was to characterize mass transfer and endogenous metabolic phenomena of the tissue to obtain minimally processed apples. The presence of CaLac and AA in solution affected the mass transfer of water and solutes, which was attributed to the changes in the cellular structure and thus to spaces available for solute transport. The metabolic heat production in samples treated in sucrose solutions was slightly lower than in untreated samples, and it was further reduced with CaLac addition. However, samples impregnated with AA exhibited a higher heat production due to a metabolic response of the tissue to AA treatment. When combined with CaLac, the heat production decreased to a level lower than untreated samples, except for those that were treated for 120 and 240min (higher impregnation), achieving the highest heat production values. These results confirm previous findings, suggesting that AA solution can promote a stress response on specific fresh-cut vegetable tissues, as well as an increase of their endogenous metabolic activity, as confirmed by the higher O2 consumption observed with the head space gas determination.

Hybrid Drying of Carrot Preliminary Processed with Ultrasonically Assisted Osmotic Dehydration.

In this paper the kinetics of osmotic dehydration of carrot and the influence of this pretreatment on the post-drying processes and the quality of obtained products are analysed. Osmotic dehydration was carried out in the aqueous fructose solution in two different ways: with and without ultrasound assistance. In the first part of the research, the kinetics of osmotic dehydration was analysed on the basis of osmotic dewatering rate, water loss and solid gain. Next, the effective time of dehydration was determined and in the second part of research samples were initially dehydrated for 30 min and dried. Five different procedures of drying were established on the grounds of convective method enhanced with microwave and infrared radiation. The influence of osmotic dehydration on the drying kinetics and final product quality was analysed. It was found that it did not influence the drying kinetics significantly but positively affected the final product quality. Negligible influence on the drying kinetics was attributed to solid uptake, which may block the pores, hindering heat and mass transfer. It was also concluded that the application of microwave and/or infrared radiation during convective drying significantly influenced the kinetics of the final stage of drying. A proper combination of aforementioned techniques of hybrid drying allows reducing the drying time. Differences between the particular dehydration methods and drying schedules were discussed.

Mass Transfer Kinetics of Osmotic Dehydration of Pineapple

Current study deals with the kinetics and mathematical modelling of osmotic dehydration of pineapple. Pineapple (Ananas comosus), 10 mm thick slices weighing 50 g each, was studied for the osmotic dehydration using hypertonic solutions of sucrose and fructose. The osmotic dehydration process was performed using three levels of temperature 40°C, 50°C and 60°C, three levels of osmotic solution concentration (40%, 50% and 60%) with sample to solution ratio maintained at 1:4, 1:5 and 1:6 respectively. After each interval of time, moisture loss and solid gain was recorded. It was found that moisture loss and solid gain increased with increase in osmotic temperature and osmotic solution concentration. The highest mass transfer was observed at concentration of 60% and temperature of 60°C. Three models (Handerson and Pabis model, Logarithmic model and Lewis model) were used to analyze osmotic dehydration data. Among the three models, Logarithmic model showed a best fit to the osmotic dehydration data with higher value of coefficient of determination (R2).

Mass transfer kinetics during osmotic processing of beef meat using ternary solutions

Osmotic dehydration of meat is usually accomplished by the use of NaCl, leading to increased salt uptake and making the final product less desirable. The effect of ternary solutions, containing maltodextrin and NaCl, on osmotic dehydration kinetics of beef meat was investigated. Beef meat slices were immersed in solutions containing (a) 5% NaCl plus 40, 50 or 60% maltodextrin, and (b) 20 or 25% NaCl for 3h at 5, 15 and 25°C. Water loss, solids gain and salt content were measured and their corresponding mass transfer coefficients were calculated applying Fick’s second law of diffusion, Peleg’s model, Azuara’s model and the simplification of Fick’s equation. The osmotic processing resulted in 7.2–19.6% water loss and 4.7–8.5% solids gain, depending on the concentration of the osmotic medium. The models used for the estimation of the diffusion coefficients demonstrated good model fit, with the simplification of Fick’s equation producing the best results. The diffusion coefficients obtained from Fick’s law were 1.15×10−9–2.67×10−9m2/s for maltodextrin and 1.24×10−9–2.10×10−9m2/s for NaCl. Substitution of NaCl, as an osmotic agent, by combinations of maltodextrin plus NaCl is feasible, attaining the desired moisture loss and lowering NaCl uptake levels.

Ultrasound-assisted osmotic dehydration and convective drying of apples: Process kinetics and quality issues

Abstract The aim of the present theme issue was to study the influence of ultrasound enhancement on the kinetics of osmotic dehydration and the effect of convective drying from the point of view of drying time and quality of dried products. Apple fruit was used as the experimental material. The kinetics of osmotic dehydration with (UAOD) and without (OD) ultrasound enhancement were examined for 40% fructose and sorbitol solutions. The effective dehydration time of osmotic process was determined. Preliminary dehydrated samples with OD and UAOD were next dried convectively with (CVUS) and without (CV) ultrasound assistance. The influence of OD and UAOD on the kinetics of CV and CVUS drying was analysed. The parameters of water activity and colour change were measured for the assessment of product quality after drying process.

Osmotic dehydration kinetics of banana slices considering variable diffusivities and shrinkage

ABSTRACTThis article studied the use of diffusion models to describe variation of water quantity and sucrose quantity during osmotic dehydration of bananas cut into cylindrical slices. Bananas with radius of 1.7 cm and 18 °Brix (on average) were cut into 1.0 cm of thickness. A solution was proposed for the diffusion equation in cylindrical coordinates using the finite volume method, with fully implicit formulation. The diffusion equation was discretized assuming diffusivities and dimensions with variable values for the banana slices. Boundary conditions of the third kind have also been considered. The osmotic dehydration experiments were conducted in binary solutions (water and sucrose) under conditions of 40 and 60 °Brix and temperatures of 40 and 70°C. Mathematical modeling was proposed to describe the processes presented good results for water quantity and sucrose quantity, with good statistical indicators for all fits.

Pulsed vacuum osmotic dehydration of tomatoes: Sodium incorporation reduction and kinetics modeling

Semi-dehydrated food is obtained via osmotic dehydration (OD). The influence of the osmotic agent (27.5% sucrose or maltodextrin combined with 10.0% of NaCl, 40 °C) with/without the application of a vacuum pulse (VP) (100 mbar, 20 min) on the NaCl incorporation and on the kinetics of water loss (WL), solid gain (SG), and water activity (aw) were studied in the OD of sliced tomatoes. The kinetics of the WL and SG were evaluated and fitted with diffusive and hydrodynamic models. The NaCl incorporation was 25% lower in the maltodextrin-NaCl solution (MN) compared to the sucrose-NaCl solution (SN). The MN reduced that incorporation compared to the SN. Moreover, the salt incorporation was significantly reduced (by approximately 50%) by using a VP in the osmotic process, which was independent of the ternary solution. The variable effective diffusivity improved the fitness of the OD kinetics with respect to the constant diffusivity or the modelling of the hydrodynamic mechanism. The large reduction of NaCl incorporation obtained in the present work, which was mainly due to the use of a VP, suggests that more attention is necessary in studies of OD with vacuum pulse involving the immersion of food in a ternary.

Studies on Mass Transfer and Diffusion Coefficients in Elephant Foot Yam (Amorphophallus spp.) during Osmotic Dehydration in Sodium Chloride Solution

The aim of this work was to study the osmotic dehydration kinetics of elephant foot yam (Amorphophallus spp.) cubes in different concentrations (5, 10 and 15% w/w) and temperatures (40, 50 and 60C) of sodium chloride solutions. Water loss and solid gain ranged from 16.69 to 33.97 and 6.65 to 12.95 g/100 g, respectively, for all the process parameters applied. The mass transfer rate was initially higher and becomes negligible after 150 min. The normalized moisture and normalized solid content vary from 0.74 to 0.88 and 1.38 to 1.72 g/g, respectively, at the end of osmotic dehydration. Azuara model was the best-fitted model among all the models applied for both water loss and solute gain and also used to predict equilibrium values. The effective diffusivity of water loss as well as solute gain was estimated for parallelepiped/slab geometry and varied from 7.380–8.564 × 10−09 and 6.780–7.921 × 10−09 m2/s, respectively, for the earlier conditions of osmotic dehydration. Practical Applications Elephant foot yam (EFY) is a medicinal and nutritional tuber crop mainly consumed as vegetable, pickles and Ayurvedic preparations. Because of its culinary properties, therapeutic values and medicinal utility, it is also referred to as “king of tuber crops.” In spite of its valuable properties, a large-scale production in any processed form is not carried out. It can be converted into a number of value-added products if processed properly and can effectively enhance the consumption by utilizing its functional benefits. For converting into value-added products or preserving it for a long time, drying is necessary as EFY contain high moisture content, but bioactive compounds significantly degrade. A good idea in this regard is osmotic dehydration, which minimizes nutritional losses of raw materials, without causing too much increase in process costs. For increasing shelf stability and processing on a commercial level, the primary step is to study mass transfer behavior and diffusion coefficients.

Osmotic dehydration tamarind pulp (Tamarindus indica L.): influence of temperature and concentration

Industrial osmotic food dehydration improves the quality of horticultural products and increases its stability. In this study the kinetics of osmotic dehydration of tamarind pulp (Tamarindus indica L.) was evaluated based on the index of effectiveness and the influence of temperature and solution concentration on the process was determined. The experimentally water loss and weight loss and the gain of solids during osmotic dehydration within hypertonic sucrose solutions of 30, 40 and 60°Brix, and temperatures of 29 and 50°C was studied. The results showed that the higher the solution concentration and temperature, a higher water loss (53.9%), weight (53.9%) and solid gain (0,008%) was produced.

Effect of calcium on the osmotic dehydration kinetics and quality of pineapple

The effects of the sucrose and calcium lactate concentrations on the osmotic dehydration kinetics of pineapple, and the diffusivity of each component were investigated. The color, water activity, texture and fruit composition were also evaluated. Osmotic dehydration was carried out using 40% and 50% sucrose solutions with added 0%, 2% or 4% calcium lactate for 1, 2, 4 and 6h of processing time. In general, the gain in calcium was greater in samples submitted to solutions with higher sucrose and calcium lactate concentrations. The greatest calcium contents (≈90mg/100g) were reached after 6h of impregnation in both 40% and 50% sucrose solutions containing 4% calcium lactate. The addition of calcium to the osmotic solution reduced the water content of the product and solute incorporation rate, inhibiting sucrose impregnation and increasing process efficiency. The addition of 4% calcium lactate to the solution increased all diffusivities in comparison to the addition of 2% but not in relation to treatments with no added calcium. Calcium impregnation did not influence the color of the product or the value for stress at rupture, as compared to raw pineapple. The diffusion coefficients presented in this work permitted the selection of the appropriate sucrose and calcium concentrations and the calculation of the processing time to give the desired product composition.

Effect of liquid nitrogen pretreatments on osmotic dehydration of blueberries

Fresh blueberries are highly perishable and must be preserved by either freezing or drying technologies. However, moisture impermeability of their skin is a barrier against the moisture diffusion slowing down the drying process. The aim of this study was to investigate the impact of liquid nitrogen pretreatments on osmotic dehydration kinetics of two blueberry species, Vaccinium corymbosum L. and Vaccinium angustifolium Ait, and on the physicochemical quality of dehydrated fruits.The number of immersions in liquid nitrogen was a determinant factor that accelerated water loss. Depending on the blueberry species, a reduction of dehydration time from 45% to 65% was obtained for liquid nitrogen treated samples when compared to control blueberries. Microscopic observations of the blueberry skin before and after the liquid nitrogen pretreatment revealed a decrease of the cuticle thickness, dewaxing of the skin surface and the presence of micro-fissures facilitating moisture and sugar transfer during the osmotic process. The dewaxing of the blueberry skin due to liquid nitrogen immersions was confirmed by wax quantification before and after the cryogenic pretreatments. Osmotic dehydration and liquid nitrogen pretreatments showed a slight decrease in the levels of phenolic compounds and anthocyanins compared to the fresh blueberries.

Osmotic Dehydration of Nectarines: Influence of the Operating Conditions and Determination of the Effective Diffusion Coefficients

The aim of the present work is to study the kinetics of osmotic dehydration of Caldesi nectarines (Prunus persica var. nectarina) evaluating the effect of osmotic solution concentration, type of solute, temperature, fruit/solute ratio and process time on moisture content, water loss, soluble solids content and solids gain. The process analysis was carried out experimentally and numerically through the mathematical modelling of mass transfer. Hypertonic solutions of glucose syrup and sorbitol (40 and 60 % w/w) were used for dehydration, during 2 h of process at temperatures of 25 and 40 °C, with fruit/osmotic agent ratio of 1:4 and 1:10. Water loss and solids gain showed significant differences depending on the type and concentration of the osmotic agent, process time and fruit/solution ratio. The concentration interacted significantly with all variables; in addition, there was an interaction between the type of osmotic agent and the relationship between fruit and the osmotic agent. The effective diffusion coefficients were obtained from the analytical solution of Fick’s second law applied to flat-plate geometry and by solving the mass transfer microscopic balances by finite element method, taking into account the real geometry of the nectarine pieces. The values obtained from Fick’s law varied between 1.27 × 10−10 and 1.37 × 10−08 m2 s−1 for water and from 1.14 × 10−10 to 1.08 × 10−08 m2 s−1 for soluble solids, while the values calculated by finite elements method ranges were between 0.70 × 10−09 and 4.80 × 10−09 m2 s−1 for water and between 0.26 × 10−09 and 1.70 × 10−09 m2 s−1 for soluble solids. The diffusion coefficients values obtained from the numerical solution are consistent with those published in literature.

Desidratação osmótica de fatias de jaca

O presente trabalho foi realizado com o objetivo de estudar a cinética e modelagem do processo de desidratação osmótica de fatias de jaca em geometria plana. O tratamento osmótico foi conduzido a 43 ºC, com agitação, utilizando-se de soluções de sacarose, nas concentrações de 40 e 50 ºBrix. O estudo da cinética de desidratação osmótica mostrou que na solução de sacarose a 50 ºBrix o valor da perda de água (WL) foi maior ao final de 28,5 horas de processo (68,5% b.u para 40,2% b.u.), ligeiramente superior ao encontrado para a solução de sacarose a 40 ºBrix, (68,5% b.u para 43% b.u.). Comportamento contrário ocorreu para o ganho de sólidos (SG). O ajuste dos dados experimentais foi realizado através dos modelos de Page e Fick. Pela análise da equação de Fick, verificou-se que os coeficientes de difusividade efetiva foram 0,5837 e 0,6677 mm² min-1 para 40 e 50 ºBrix, respectivamente.