Effect of Blanching and Vacuum Pulse Application on Osmotic Dehydration of Pear

2003 ◽  
Vol 9 (5) ◽  
pp. 321-328 ◽  
Author(s):  
M. Chafer ◽  
C. Gonzalez-Martinez ◽  
B. Fernandez ◽  
L. Perez ◽  
A. Chiralt
Keyword(s):  
Water Loss ◽  
Atmospheric Pressure ◽  
Transfer Rate ◽  
Osmotic Dehydration ◽  
Mass Transfer Rate ◽  
Structural Response ◽  
External Solution ◽  
Gas Release ◽  
Volume Compression ◽  
Pre Treatment

Osmotic dehydration of pear cylinders (var. blanquilla) was studied by analysing the effect of blanching pre-treatment and the application of a vacuum pulse on the kinetics and yield of the process and on product quality (colour and mechanical behaviour). Fresh and stem-blanched samples were treated with 65 Brix sucrose at atmospheric pressure and by applying a vacuum pulse (50 mbar for 5 min). The influence of the sugar gain and water loss fluxes, and the tissue structural response to the vacuum pulse, on the total mass and volume losses of the samples has been discussed. Blanching implied an increase in the mass transfer rate in pear tissue. Vacuum pulse in blanched samples resulted in more volume compression than sample impregnation with the external solution due to the sample softening by thermal effect and to the partial gas release during its thermal expansion. This provoked the greatest volume losses and a reductionof the ratio of sugar gain to water loss, where the highest values reached were for non-blanched samples submitted to vacuum pulse. Mechanical changes induced by treatments were similar inall cases, but colour hue and chrome were better preserved in samples treated by PVOD. Nevertheless, this treatment implied a transparency gain due to the sample gas release and so, samples become darker.

scholarly journals Vacuum-Assisted Osmotic Dehydration of Autumn Olive Berries: Modeling of Mass Transfer Kinetics and Quality Assessment

Foods ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2286
Author(s):  
Mohamed Ghellam ◽  
Oscar Zannou ◽  
Charis M. Galanakis ◽  
Turki M. S. Aldawoud ◽  
Salam A. Ibrahim ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Water Loss ◽  
Atmospheric Pressure ◽  
Sucrose Solution ◽  
Osmotic Dehydration ◽  
Vacuum System ◽  
Pressure System ◽  
Solid Gain ◽  
Autumn Olive ◽  
Mass Transfer Kinetics

Autumn olive fruits were osmo-dehydrated in sucrose solution at 70 °C under vacuum and atmospheric pressure. The mass transfer kinetics data were applied to the models of Azuara, Crank, Page, and Peleg. The Peleg model was the best-fitted model to predict the water loss and solid gain of both treatments. The vacuum application decreased the effective diffusivities from 2.19 × 10−10 to 1.55 × 10−10 m2·s−1 for water loss and from 0.72 × 10−10 to 0.62 × 10−10 m2·s−1 for sugar gain. During the osmotic dehydration processes, the water activity decreased and stabilized after 5 h, while the bulk densities increased from 1.04 × 103 to 1.26 × 103 kg/m3. Titratable acidity gradually reduced from 1.14 to 0.31% in the atmospheric pressure system and from 1.14 to 0.51% in the vacuum system. pH increased significantly in both systems. Good retention of lycopene was observed even after 10 h of treatments. For the color parameters, the lightness decreased and stabilized after 30 min. In comparison, the redness and yellowness increased in the first 30 min and gradually decreased towards the initial levels in the fresh fruit.

scholarly journals Effect of air drying on quality characteristics and mass transfer kinetics of osmotically dehydrated sea buckthorn by stevia

Food Research ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 1140-1150
Author(s):  
G. Lentzou ◽  
Ch. Templalexis ◽  
G. Xanthopoulos
Keyword(s):  
Ascorbic Acid ◽  
Water Loss ◽  
Dry Matter ◽  
Osmotic Dehydration ◽  
Sea Buckthorn ◽  
Air Drying ◽  
Solid Gain ◽  
Steviol Glycoside ◽  
Water Diffusivity ◽  
Pre Treatment

Sea buckthorn is ranked among the most significant super foods worldwide. Its fruits and leaves are used as fresh or dried in food, pharmaceutical and cosmetic industry. As super food any pre-treatment should sustain this property and hence this research was focused on osmotic dehydration of sea buckthorn by stevia also a super food. Therefore, water loss, sugar gain, acidity, ascorbic acid and water diffusivity were evaluated during osmotic dehydration of sea buckthorn by two stevia solutions, 15ο and 30οBrix and following were air-dried at 50οC by comparing the effect of steam blanching per case. Steam blanched samples exhibited increased water loss at the end of the process, 55% at 30οBrix and 48% at 15οBrix, compared to untreated samples where losses were 43% (30οBrix) and 28% (15οBrix) respectively. Ascorbic acid was significantly reduced, exceeding 50% in steam blanched samples and 23% in untreated samples. Steam blanched samples dehydrated at 15oBrix exhibited 82% dry matter increase and only 39% the untreated samples. Similarly, samples dehydrated at 30oBrix exhibited 84% dry matter increase and 53% when no steam blanching was applied. Solid gain was seven times less compared to water loss which is attributed to high molecular weight of steviol glycoside. The osmotic dehydration and airdrying curves were described effectively by Peleg and Fick models, and Logarithmic and Fick models respectively, having in all cases R2 adj>99% and SEE<0.2. The water diffusivity of steam blanched samples was 3.2-5.57×10-11 m 2 /s for water loss and 1.27- 2.03×10-11 m 2 /s for solid gain at 30oBrix and 2.12-4.27×10-11 m 2 /s and 0.91-1.98×10-11 m 2 /s at 15oBrix. Finally, the water diffusivity of steam blanched samples during air-drying was 2.11-2.29×10-11 m 2 /s and 1.56-1.66×10-11 m 2 /s in the case of untreated samples.

Transport Mechanisms in Osmotic Dehydration: The Role of the Structure

2003 ◽  
Vol 9 (3) ◽  
pp. 179-186 ◽  
Author(s):  
A. Chiralt ◽  
P. Fito
Keyword(s):  
Mass Transfer ◽  
Mass Transport ◽  
Atmospheric Pressure ◽  
Osmotic Dehydration ◽  
External Solution ◽  
Bulk Flow ◽  
Solute Diffusion ◽  
Structural Level ◽  
Intercellular Spaces ◽  
Water Release

Osmotic dehydration promotes water release from a cellular material immersed in a concentrated solution, while a simultaneous external solute uptake happens. Mass transfer occurs during this operation through different mechanisms to a different extent depending on process variables. The action of the different mechanisms, balanced by controlling those variables, makes possible to achieve a specific dewateringsolute uptake ratio in the final product. Mechanisms involved in mass transfer during osmodehydration of cellular tissues depend on the structural level of the tissue. The external broken cells can be easily impregnated by the external solution, and in the intercellular spaces, bulk flow of solution, water and solute diffusion occur. The bulk flow is promoted due to capillary pressure in processes carried out at atmospheric pressure. Nevertheless, when vacuum is applied to the system, capillary impregnation is promoted and when the atmospheric pressure is restored, pores are extensively flooded with the external solution and depending on the applied compression ratio. Mass transport in the intercellular spaces is mainly responsible for solute gain. At cellular level, cell wall and membranes act as non-selective and selective barriers respectively to mass transport and the transmembrane flux is responsible for most of the cell-to-cell water transport during osmotic dehydration of tissues.

scholarly journals Osmotic Dehydration of Apples Under Reduced Pressure Conditions

2016 ◽  
Vol 20 (3) ◽  
pp. 135-143 ◽  
Author(s):  
Siemowit Muszyński ◽  
Krzysztof Kornarzyński ◽  
Bożena Gładyszewska
Keyword(s):  
Weight Loss ◽  
Weight Gain ◽  
Water Loss ◽  
Atmospheric Pressure ◽  
Sucrose Solution ◽  
Osmotic Dehydration ◽  
Total Weight Loss ◽  
Reduced Pressure ◽  
Pressure Application ◽  
Osmotic Solution

AbstractThe aim of the study was to determine the effect of reduced pressure on the osmotic dehydration of apples. Tests were performed under vacuum of 8 kPa, 67 kPa, 80 kPa and under the atmospheric pressure (100 kPa). The samples were dehydrated in a sucrose solution with a concentration of 30°Bx, 50°Bx and 70°Bx. It has been shown that the effect of low pressure application depends significantly to the concentration of the osmotic solution. It has been found that the overall weight change significantly depend on the concentration of the solution, and after 3 hours of dehydration at a pressure of 80 kPa at solutions of 30°Bx, 50°Bx and 70°Bx total weight loss increased by 65%, 12% and 25% respectively, when compared to samples dehydrated at atmospheric pressure. From the studied variants of reduced pressure, the pressure of 80 kPa seems to be the optimal one, as evidenced by the lowest values of weight gain to water loss ratios for apples dehydrated in solutions of 50°Bx and 70°Bx.

Free Convective Mass Transfer at Isosceles Triangular Surfaces of Varying Inclination

2003 ◽  
Vol 68 (11) ◽  
pp. 2080-2092 ◽  
Author(s):  
Martin Keppert ◽  
Josef Krýsa ◽  
Anthony A. Wragg
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Mass Transfer Process ◽  
Sulfate Solution ◽  
Convective Mass Transfer ◽  
Varying Length ◽  
Inclined Surface ◽  
Vertical Case ◽  
Limiting Diffusion Current

The limiting diffusion current technique was used for investigation of free convective mass transfer at down-pointing up-facing isosceles triangular surfaces of varying length and inclination. As the mass transfer process, copper deposition from acidified copper(II) sulfate solution was used. It was found that the mass transfer rate increases with inclination from the vertical to the horizontal position and decreases with length of inclined surface. Correlation equations for 7 angles from 0 to 90° were found. The exponent in the ShL-RaL correlation ranged from 0.247 for the vertical case, indicating laminar flow, to 0.32 for inclinations of 60 to 90°, indicating mixed or turbulent flow. The general correlation ShL = 0.358(RaL sin θ)0.30 for the RaL sin θ range from 7 × 106 to 2 × 1011 and inclination range from 15 to 90° was obtained.

Thermal analysis of higher-order chemical reactive viscoelastic nanofluids flow in porous media via stretching surface

2021 ◽  
pp. 095440622110084
Author(s):  
Mohamed R Eid ◽  
F Mabood
Keyword(s):  
Brownian Motion ◽  
Transfer Rate ◽  
Fluid Velocity ◽  
Mass Transfer Rate ◽  
Higher Order ◽  
Flow In Porous Media ◽  
Viscoelastic Parameter ◽  
Suction Parameter ◽  
And Brownian Motion ◽  
Magnetic Strength

The essence of the present investigation is to reveal the hydrothermal variations of viscoelastic nanofluid flow in a porous medium over a stretchable surface. A higher-order chemical reaction is incorporated with thermophoresis and Brownian motion. Similarity conversions reduce the resulting equations into their dimensionless form and then solved using Runge-Kutta-Fehlberg (RKF) based shooting procedure. The effects of underlying factors on the flow are discussed through various graphs and tables. Computational results for noteworthy skin friction and heat and mass transport are presented and reviewed with sensible judgment. The study reveals that the fluid velocity reduces with incremental values of the viscoelastic parameter [Formula: see text] and magnetic strength. The temperature reduces for the suction parameter with the existence of stretchable but enhances with thermophoresis and Brownian motion effects. Heat transfer rate amplifies for [Formula: see text] but declines for [Formula: see text]. Mass transfer rate increases with the increase in Brownian parameter and Schmidt number. A comparative analysis shows a better agreement with previous results in limiting scenarios.

scholarly journals Impact of double-diffusive convection and motile gyrotactic microorganisms on magnetohydrodynamics bioconvection tangent hyperbolic nanofluid

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 74-88 ◽  
Author(s):  
Tanveer Sajid ◽  
Muhammad Sagheer ◽  
Shafqat Hussain ◽  
Faisal Shahzad
Keyword(s):  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Physical Nature ◽  
Working Fluid ◽  
Nonlinear Ordinary Differential Equations ◽  
Gyrotactic Microorganisms ◽  
Motile Gyrotactic Microorganisms ◽  
Double Diffusive

AbstractThe double-diffusive tangent hyperbolic nanofluid containing motile gyrotactic microorganisms and magnetohydrodynamics past a stretching sheet is examined. By adopting the scaling group of transformation, the governing equations of motion are transformed into a system of nonlinear ordinary differential equations. The Keller box scheme, a finite difference method, has been employed for the solution of the nonlinear ordinary differential equations. The behaviour of the working fluid against various parameters of physical nature has been analyzed through graphs and tables. The behaviour of different physical quantities of interest such as heat transfer rate, density of the motile gyrotactic microorganisms and mass transfer rate is also discussed in the form of tables and graphs. It is found that the modified Dufour parameter has an increasing effect on the temperature profile. The solute profile is observed to decay as a result of an augmentation in the nanofluid Lewis number.

Distributed mass transfer rate for modelling the leaching of porous granular materials containing soluble pollutants

2000 ◽  
Vol 55 (7) ◽  
pp. 1257-1267 ◽  
Author(s):  
Tiruta-Barna Ligia ◽  
Barna Radu ◽  
Moszkowicz Pierre ◽  
Bae Hae-Ryong
Keyword(s):  
Mass Transfer ◽  
Granular Materials ◽  
Transfer Rate ◽  
Mass Transfer Rate
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