Azuara Model Research Articles

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.

Influence of the process parameters on osmotic dehydration of mapara (Hypophthalmus edentatus) fillet.

The effects of temperature, time, pressure and brine concentration were assessed during osmotic dehydration (OD) of H. edentatus fillet. The response surface methodology (RSM) showed that using vacuum during the OD process did not cause a statistically significant change (p > 0.05) on the water loss (WL), solid gain (SG) and water activity (aw). The other factors showed a statistically significant effect (p ≤ 0.05) on at least one of these responses. Through RSM, the following condition could be defined for the OD process: brine concentration at 25% NaCl, 25°C, 120min and atmospheric pressure. The Azuara model was shown to be effective in predicting the WL and SG kinetics during the OD process. 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 4.73 × 10(-10)m(2)/s for WL and 1.33 × 10(-9)m(2)/s for SG.

Elephant Foot Yam (Amorphophallus paeoniifolius): Osmotic Dehydration and Modelling

Osmotic dehydration of elephant foot yam was done in different concentration of sucrose solution at different temperature for regular interval of time. The osmotic solution concentrations used were 40, 50, 60°Bx, osmotic solution temperatures were 35, 45, 55°C and the process duration varied from 0 to 240 min. The fruit to solution ratio was kept constant i.e. 1:5 (w/w) during all the experiments. The experimental data of water loss and solute gain was fitted to different empirical kinetic models viz. Peleg, Penetration, Magee, and Azuara to know the best fitted model to the experimental data. Out of all the applied models, Magee model and Azuara model were the best fitted as compared to other models for water loss and solute gain of elephant foot yam, respectively.

Kinetic Modeling and Mass Diffusivities during Osmotic Treatment of Red Abalone (H aliotis rufescens ) Slices

Osmotic dehydration of abalone slices was carried out in order to look into the influence of osmotic concentration (15, 20 and 25% NaCl w/v) and solution temperature (25, 45 and 65C) on mass transfer kinetics and diffusion coefficients. Moisture and solid diffusivities values were 2.70–10.76 × 10−10 and 1.31–2.41 × 10−10 m2/s, respectively. Activation energy values from 23.56 to 80.24 kJ/mol for both diffusivities were estimated. Moisture and solid diffusion coefficients were influenced by both factors. A multiple linear regression test was performed on the combined effect of osmotic concentration and solution temperature during osmotic treatment. Modeling of mass transfer kinetics for moisture loss and solid gain were performed according to three mathematical models: Penetration, Magee and Azuara. Thus, based upon statistical tests (R2, sum squared error, root mean square error and χ2), the Azuara model was the most suitable to describe the mass transfer phenomena during osmotic process of abalone slices. Practical Applications The abalone has a great demand in international markets, even when it is pretty expensive, thus the need to increase its shelf life is relevant from an economic point of view as well as quality product. Therefore, osmotic dehydration is an excellent alternative, as the abalone is cooked and simultaneously preserved under a salt solution. Furthermore, this osmotic treatment could also act further on as a pretreatment for any other drying method either by convective, freeze-drying, microwave, etc. That is why, this work proposes to research the effects of osmotic concentration and solution temperature on the kinetics of mass transfer during osmotic dehydration of abalone slices samples by different mathematical models. Thereby, osmotic treatment modeling of abalone slices, under conditions stated earlier, could be very helpful in predicting moisture/salt final content and process times as well as anticipating and dealing any problem during processing.

Mass Transfer During Osmotic Dehydration of Chub Mackerel Cylinders in Ternary Solution

<p>In the analysis, design and optimization of an osmotic dehydration process is important to know the kinetic of water loss and solutes gain. In this study, the mass transfer during osmotic dehydration of chub mackerel (<em>Scomber japonicus</em>) cylinders in ternary solution glycerol/salt/water was analyzed. The models of Zugarramurdi & Lupín and Azuara were used to describe mass transfer and to estimate equilibrium values. The radial effective diffusion coefficient was estimated using the analytical solution of Fick's second law. Diffusion coefficients were determined for a finite cylinder, for an infinite cylinder considering only the first term of the series and considering higher order terms of the series. The profiles of water and solutes during the osmotic dehydration were calculated by using the estimated water and solutes diffusivities. According to the results obtained, using three terms in the analytical solution of the Fick's second law is appropriate to determine the diffusion coefficients. The diffusion coefficient for infinite cylinder were 2.63×10<sup>-6</sup>, 4.11×10<sup>-6</sup> and 4.25×10<sup>-6</sup> cm<sup>2</sup>/s for water loss, salt and glycerol gain respectively. For a finite cylinder these values were 2.30×10<sup>-6</sup>, 3.67×10<sup>-6</sup> and 3.78×10<sup>-6</sup> cm<sup>2</sup>/s respectively. All the models proposed were in agreement with experimental data for solutes gain ((0.967<R<sup>2</sup><sub>adj</sub><0.986); (0.0016<<em>RMSE</em><0.039) and (4.17<<em>P</em><10.0)). The model based on the solution of Fick’s Law for an infinite cylinder with higher order terms was the best fit for water loss and solutes gain. The equilibrium values estimated with Azuara model agree with the experimental (0<relative error<9.8). Water and solute distributions as a function of time and location in the radial direction were plotted.</p>

Modeling and Optimization of Microwave Osmotic Dehydration of Apple Cylinders Under Continuous-Flow Spray Mode Processing Conditions

The objective of this study was to model and optimize the mass transfer behavior during microwave osmotic dehydration of apple cylinders under continuous-flow spray mode processing conditions. Data needed for the model development and optimization were obtained using a central composite rotatable experimental design involving sucrose concentration (33.3–66.8°B), temperature (33.3–66.8 °C), flow rate (2,120–3,480 ml/min), and contact times (5–55 min); and the response variables were moisture loss, solids gain, and weight loss. Mass transfer kinetics was evaluated based on the empirical Azuara model and the conventional diffusion model. Diffusivities of both moisture loss (Dm) and solids gain (Ds) obtained from the diffusion model were related to sucrose concentration, temperature, and flow rate. Optimization was evaluated using a desirability function model which could be used with several imposed constraints. The optimum conditions obtained depended on the imposed constraints. A set of constraints involving maximizing moisture loss and weight reduction while keeping the solids gain below 3.5% gave the following optimal conditions: a 30-min osmotic treatment at 65°B, 60 °C, and 2,800 ml/min flow rate yielding a moisture loss of 40.9%, weight reduction of 37.7%, with a solids gain of 3.32%.

Mass Transfer Kinetics during Osmotic Dehydration of Pomegranate Arils

The mass transfer kinetics during osmotic dehydration of pomegranate arils in osmotic solution of sucrose was studied to increase palatability and shelf life of arils. The freezing of the whole pomegranate at -18 °C was carried out prior to osmotic dehydration to increase the permeability of the outer cellular layer of the arils. The osmotic solution concentrations used were 40, 50, 60°Bx, osmotic solution temperatures were 35, 45, 55 °C. The fruit to solution ratio was kept 1:4 (w/w) during all the experiments and the process duration varied from 0 to 240 min. Azuara model and Peleg model were the best fitted as compared to other models for water loss and solute gain of pomegranate arils, respectively. Generalized Exponential Model had an excellent fit for water loss ratio and solute gain ratio of pomegranate arils. Effective moisture diffusivity of water as well as solute was estimated using the analytical solution of Fick's law of diffusion. For above conditions of osmotic dehydration, average effective diffusivity of water loss and solute gain varied from 2.718 × 10(-10) to 5.124 × 10(-10) m(2)/s and 1.471 × 10(-10) to 5.147 × 10(-10) m(2)/s, respectively. The final product was successfully utilized in some nutritional formulations such as ice cream and bakery products.

Evaluation of Diffusion and Azuara Models for Mass Transfer Kinetics during Microwave-Osmotic Dehydration of Apples under Continuous Flow Medium-Spray Conditions

Azuara and diffusion models were evaluated for describing the mass transfer kinetics of apple (Red Gala) cylinders during microwave-osmotic dehydration under continuous-flow medium-immersion (MWODI) and medium-spray (MWODS) conditions as well as immersion (CODI) and spray (CODS) conditions without the microwave heating. Two different sets of experiments were carried out with all four methods. In the first set, osmotic treatments were given at 50°C/50°Brix and 40°C/40°Brix with a solution flow rate of 2800 mL/min and fruit-to-solution ratio of 1:30. The treatment times ranged from 0 to 120 min. In the second set, the MWODS was extended to other conditions (40°C–50°Brix and 50°C–40°Brix). The equilibrium moisture loss and equilibrium solid gains required for the diffusion model were predicted using the Azuara model. Both models well fitted the experimental data for mass transfer kinetics (R2 > 0.92). Higher equilibrium moisture loss and lower solid gain were observed in samples treated with MWODS compared with other methods. The equilibrium moisture loss and solid gain under MWODS were related to solution concentration and solution temperature. The diffusion coefficients representing moisture loss (Dm) and solid gain (Ds) were computed from the diffusion model. The Dm values for were higher and Ds values were lower with MWODS as compared to the other methods. Dm and Ds were dependent on temperature and concentration of the osmotic solution. Half-drying time for moisture loss and solids gain were also computed to compare the different methods. These were inversely related to diffusivity values. Overall, the highest moisture loss and the lowest solids gain were observed in MWODS.

Effect of Blanching by Ohmic Heating on the Osmotic Dehydration Behavior of Apple Cubes

The effect of blanching by ohmic heating (OH) on the damage to apple tissues and subsequent osmotic dehydration kinetics was investigated. Apple cubes were heated ohmically to various blanching scales. Heating temperature and duration were, respectively, 60–95 ± 2°C and 0–6 min. After cooling, the treated samples were put into sucrose solutions (70 °B) for the osmotic dehydration (OD). The equilibrium state of osmotic dehydration was estimated using the Azuara model. Ohmic heating leads, even for short treatments, to significant changes in the cellular structure of apples and to the enhancement of mass transfer during osmotic dehydration.

Osmotic dehydration kinetics of carrot cubes in sodium chloride solution

SummaryOsmotic dehydration kinetics of carrot cubes in sodium chloride solution having concentrations 5%, 10% and 15% (w/v), solution temperature 35, 45 and 55 °C, sample to solution ratio (STSR) 1:4, 1:5 and 1:6 were studied up to 240 min duration. During the experimentation, effect of solution temperature and process duration was significant and that of solution concentration and STSR were non‐significant on water loss. Among the different models applied (Penetration model, Magee Model, and Azuara model), Azuara model best fitted to the experimental data for water loss and solute gain during osmotic dehydration. Effective diffusivities of water and solute were calculated by using the analytical solution of Fick’s unsteady state law of diffusion by iterative technique with a computer program. For the above conditions, the effective diffusivity of water was found to be in the range between 2.6323 × 10−9 and 6.2397 × 10−9 m2/s and that of solute between 3.1522 × 10−9 and 4.6400 × 10−9 m2/s.

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

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.

Study of mass transfer kinetics and effective diffusivity during osmotic dehydration of carrot cubes

The mass transfer kinetics during osmotic dehydration of carrot cubes in ternary solution of sucrose, NaCl salt and water were studied. The osmotic solution concentrations used were 50 °B + 5% salt (w/v), 50 °B + 10% salt (w/v) and 50 °B + 15% salt (w/v), osmotic solution temperature used were 35, 45 and 55°C, fruit to solution ratios 1:4, 1:5 and 1:6 and the process duration varied from 0 to 240 min. Among the models applied, Azuara model well represented the experimental data for water loss; whereas solute gain was well represented by the Magee model. Effective diffusivity of water as well as solute was estimated using the analytical solution of Fick’s law of diffusion and iterative technique, which was conducted by a simple computer program, was used to solve the equation with first six terms. For above conditions of osmotic dehydration, the effective diffusivity of water was found to be in the ranged between 1.594 × 10 −9 and 2.078 × 10 −9 m 2/s and that of solute between 1.175 × 10 −9 and 1.645 × 10 −9 m 2/s.