scholarly journals Development of a Controlled-Ventilation Box for Modified-Atmosphere Storage of Fresh Produce

Foods ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2965
Author(s):  
Nandita Keshri ◽  
Ingo Truppel ◽  
Manfred Linke ◽  
Martin Geyer ◽  
Cornelia Weltzien ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Supply Chain ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Fresh Produce ◽  
Storage Conditions ◽  
Modified Atmosphere ◽  
Modified Atmosphere Storage ◽  
Atmosphere Storage ◽  
Wall Openings

Adjusting beneficial gas concentrations in real time in response to changing storage conditions is important for fresh produce, especially throughout the supply chain when temperature abuse occurs frequently. In this study, a controlled-ventilated box for bulk transportation of fresh produce was demonstrated and tested under variable temperatures. The presented system comprised a rigid container with a miniature blower installed in the opening of its wall for facilitating the gas exchange and an additional wall opening with a metal tube protruding into the inner container’s space. The in-package atmosphere was formed by the balance between the respiratory activity of the produce and the influx of fresh air through the wall openings, regulated by switching the blower ON or OFF. The mass transfer coefficient for metal tubes of different dimensions was measured under modified atmosphere featuring 15% CO2 and 5% O2 at 10 °C. The addition of an air blower increased the mass transfer coefficient by at least 100 times. A further storage trial with cherries was successfully performed at 10 °C and 20 °C. The demonstrated trial featured some significant inputs to increase the knowledge about better storage of fresh produce throughout the supply chain and storage.

scholarly journals Effect of modified atmosphere storage on the shelf life and quality of black pepper and turmeric

1970 ◽  
pp. 20-26
Author(s):  
T J Zachariah, E Jayashree, K N Shiva
Keyword(s):  
Essential Oil ◽  
Modified Atmosphere Packaging ◽  
Dry Weight ◽  
Storage Conditions ◽  
Black Pepper ◽  
Modified Atmosphere ◽  
Ambient Storage ◽  
Modified Atmosphere Storage ◽  
Atmosphere Storage ◽  
Control Samples

Modified atmosphere packaging and storage of black pepper (var. Panniyur I) and turmeric (var. Prathiba) were studied for a period of 16 months under ambient storage conditions. Whole dry samples of black pepper and turmeric were packaged in three layered metalized polyester covers (12 μ polyester + 12 μ metalized polyester + 80 μ LDPE) under three modified storage atmospheres viz. 100% vacuum, 100% N2, 90% N2 + 10% CO2 and the control samples were stored in small size jute gunny bags. Results indicated that maximum retention of quality in terms of its essential oil and oleoresin contents of black pepper and turmeric was obtained when stored under nitrogen packaging (100% N2), followed by vacuum packaged (100% vacuum) and modified atmosphere storage of 90% N2 + 10% CO2. The essential oil content of stored black pepper reduced from 2.42% to 2.22% (dry weight basis, dwb) in all the three modified atmosphere storage with a loss of 8.26% while control recorded a loss of 16.53% during storage. The oleoresin content decreased from 7.79% to 7.44%, 7.38% and 7.32% in case of black pepper stored in 100% N2 packaged, 100% vacuum packaged and 90% N2 + 10% CO2 packaged storage atmospheres. The quality loss for turmeric in terms of essential oil, oleoresin and curcumin content at the end of storage, when packaged in 100% N2 atmosphere were 36.60%, 16.12% and 9.48%, respectively while the corresponding reduction in control samples were 40.49%, 20.27% and 19.39%.

Absorption of oxygen into solutions of polymers

1986 ◽  
Vol 51 (10) ◽  
pp. 2127-2134 ◽  
Author(s):  
František Potůček ◽  
Jiří Stejskal
Keyword(s):  
Mass Transfer ◽  
Aqueous Solutions ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Liquid Flow ◽  
Flow Curve ◽  
Liquid Flow Rate ◽  
Polymer Concentration ◽  
Newtonian Liquids

Absorption of oxygen into water and aqueous solutions of poly(acrylamides) was studied in an absorber with a wetted sphere. The effects of changes in the liquid flow rate and the polymer concentration on the liquid side mass transfer coefficient were examined. The results are expressed by correlations between dimensionless criteria modified for non-Newtonian liquids whose flow curve can be described by the Ostwald-de Waele model.

scholarly journals Development of mass and heat transfer coupled model of hollow fiber membrane for salt recovery from brine via osmotic membrane distillation

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Sher Ahmad ◽  
Gabriela Vollet Marson ◽  
Waheed Ur Rehman ◽  
Mohammad Younas ◽  
Sarah Farrukh ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Heat And Mass Transfer ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Membrane Distillation ◽  
Fiber Membrane ◽  
Salt Recovery ◽  
Osmotic Solution

Abstract Background In this research work, a coupled heat and mass transfer model was developed for salt recovery from concentrated brine water through an osmotic membrane distillation (OMD) process in a hollow fiber membrane contactor (HFMC).The model was built based on the resistance-in-series concept for water transport across the hydrophobic membrane. The model was adopted to incorporate the effects of polarization layers such as temperature and concentration polarization, as well as viscosity changes during concentration. Results The modeling equations were numerically simulated in MATLAB® and were successfully validated with experimental data from literature with a deviation within the range of 1–5%. The model was then applied to study the effects of key process parameters like feed concentrations, osmotic solution concentration, feed, and osmotic solution flow rates and feed temperature on the overall heat and mass transfer coefficient as well as on water transport flux to improve the process efficiency. The mass balance modeling was applied to calculate the membrane area based on the simulated mass transfer coefficient. Finally, a scale-up for the MD process for salt recovery on an industrial scale was proposed. Conclusions This study highlights the effect of key parameters for salt recovery from wastewater using the membrane distillation process. Further, the applicability of the OMD process for salt recovery on large scale was investigated. Sensitivity analysis was performed to identify the key parameters. From the results of this study, it is concluded that the OMD process can be promising in salt recovery from wastewater.

scholarly journals Hydrodynamics and Mass Transfer in a Concentric Internal Jet-Loop Airlift Bioreactor Equipped with a Deflector

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4329
Author(s):  
Radek Šulc ◽  
Jan Dymák
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Liquid System ◽  
Gas Holdup ◽  
Gas Velocity ◽  
Liquid Phase Mass Transfer ◽  
Homogenization Time ◽  
Standard Design ◽  
Superficial Gas Velocity

The gas–liquid hydrodynamics and mass transfer were studied in a concentric tube internal jet-loop airlift reactor with a conical bottom. Comparing with a standard design, the gas separator was equipped with an adjustable deflector placed above the riser. The effect of riser superficial gas velocity uSGR on the total gas holdup εGT, homogenization time tH, and overall volumetric liquid-phase mass transfer coefficient kLa was investigated in a laboratory bioreactor, of 300 mm in inner diameter, in a two-phase air–water system and three-phase air–water–PVC–particle system with the volumetric solid fraction of 1% for various deflector clearances. The airlift was operated in the range of riser superficial gas velocity from 0.011 to 0.045 m/s. For the gas–liquid system, when reducing the deflector clearance, the total gas holdup decreased, the homogenization time increased twice compared to the highest deflector clearance tested, and the overall volumetric mass transfer coefficient slightly increased by 10–17%. The presence of a solid phase shortened the homogenization time, especially for lower uSGR and deflector clearance, and reduced the mass transfer coefficient by 15–35%. Compared to the gas–liquid system, the noticeable effect of deflector clearance was found for the kLa coefficient, which was found approx. 20–29% higher for the lowest tested deflector clearance.

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