scholarly journals Effects of Drying Parameters on Dehydration of Green Banana (Musa sepientum) and its Use in Potato (Solanum tuberosum) Chips Formulation

2012 ◽  
Vol 10 (1) ◽  
pp. 87-97 ◽  
Author(s):  
M. S. Islam ◽  
M. A. Haque ◽  
M. N. Islam
Keyword(s):  
Mass Transfer ◽  
Rate Constant ◽  
Moisture Diffusivity ◽  
Drying Rate ◽  
Drying Time ◽  
Transfer Resistance ◽  
Air Temperatures ◽  
Model Mixing ◽  
Two Parameters ◽  
Green Banana

The present study quantifies the drying kinetics of green banana during mechanical dehydration. The effect of loading density (sample thickness) and the temperature on the drying rate constant and drying time were investigated and quantified. Drying rate increased with increasing temperature but decreased with increase in loading density. The values of exponent ‘n’ of the two parameters power law model describing the drying rate constant (as a function of thickness) were less than 2 which indicated the presence of significant external resistance to mass transfer despite the dominance of internal mass transfer resistance.  Investigation with three drying air temperatures (55, 60 and 65oC) at constant air velocity (0.6 m/sec) resulted that the increase in drying air temperature increased the drying process.  The moisture diffusivity values were 1.25×10-10, 1.67×10-10 and 2.19×10-10 m2/sec at 55, 60 and 65oC respectively. The activation energy (Ea) indicating the temperature dependence of the diffusivity was 51.21 KJ/mole obtained using Arrhenius model. Mixing of green banana flour in the potato chips formulation enhanced the fiber and mineral content in the product.DOI: http://dx.doi.org/10.3329/agric.v10i1.11069The Agriculturists 2012; 10(1): 87-97

scholarly journals Kinetics of Dehydration of Aroids and Developed Dehydrated Aroids Products

2010 ◽  
pp. 19-24
Author(s):  
M Kamruzzaman ◽  
MN Islam
Keyword(s):  
Mass Transfer ◽  
Rate Constant ◽  
Chemical Engineering ◽  
Raw Materials ◽  
Drying Rate ◽  
Chemical Compositions ◽  
Air Velocity ◽  
Transfer Resistance ◽  
Power Law Equation ◽  
Kinetics Of

The study was concerned with the dehydration kinetics of aroids in mechanical dryer at different dryingcondition such as variable air dry bulb temperature and air velocity. Fresh aroids with 3, 5 mm slice and 8mm cube were used as raw materials for drying. The experimental results showed that drying rate constantand thickness can be expressed as power law equation. The exponent of the equation for aroids was 1.15indicating presence of significance external mass transfer resistance. Increasing loading density gavedecreased drying rate constant and when air velocity of dryer was increased, drying rate constant was alsoincreased, as higher air velocity reduces the external resistance to mass transfer and also highertemperature gave faster drying rate. The activation energy of diffusion of water from aroids during dryingas per Arrhenius equation was found to be 5.12 k cal/g-mole. The chemical compositions of fresh and driedaroids were determined and it was observed that all the constituent remained almost constant, only fatdecreased slightly possibly due to oxidation. Organoleptic taste testing showed that “chapatti” preparedfrom aroids powder (aroids powder: wheat flour = 1:4) were adjudged to be the best by the panelists using1-9 hedonic scale and ranked as like moderately securing score 7.3.Journal of Chemical Engineering Vol.ChE 24 2006 19-24

Drying Kinetics, Rehydration Behavior and Morphological Properties of Pre-blanched Thai Basil Leaves

2021 ◽  
Author(s):  
Nhu Bich Ma ◽  
Thanh Thi Ha Le ◽  
Ngoc Lieu Le
Keyword(s):  
Elevated Temperatures ◽  
Microstructural Analysis ◽  
Moisture Diffusivity ◽  
Morphological Properties ◽  
Drying Rate ◽  
Drying Time ◽  
Hot Air ◽  
Air Temperatures ◽  
Best Fitting ◽  
Pre Treatment

Drying characteristics of Thai basil (Ocimum basilicum var. thyrsiflorum) leaves during hot-air drying process at different air temperatures with and without blanching pre-treatment were in-depth investigated. The increase in drying rate and decrease in drying time were observed at elevated temperatures. Blanching further reduced the drying time by approximately 19–45%, indicating to potentially reduce energy consumption of drying. The Midilli et al’s model demonstrated the best fitting to describe the process. The effective moisture diffusivity was computed as 0.21–1.55×10–10 m2s–1. The lower activation energy of water removal during drying for blanched leaves indicated that blanching had more energy efficiency at lower temperatures. Blanching also improved rehydration capacity of dried leaves. Microstructural analysis revealed that blanching caused the collapse of the cellular structure and shrinkage and hence reduced the resistance of moisture removal leading to a higher drying rate. The findings in this work prove that blanching can be a potential approach to save consumed energy, reduce drying time, and hence potentially preserve beneficial properties of bioactive compounds in agricultural plants.

scholarly journals Freeze-Drying of Blueberries: Effects of Carbon Dioxide (CO2) Laser Perforation as Skin Pretreatment to Improve Mass Transfer, Primary Drying Time, and Quality

Foods ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 211 ◽  
Author(s):  
Pablo Munzenmayer ◽  
Jaime Ulloa ◽  
Marlene Pinto ◽  
Cristian Ramirez ◽  
Pedro Valencia ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Co2 Laser ◽  
Freeze Drying ◽  
Sharp Decrease ◽  
Linear Increase ◽  
Vapor Flow ◽  
Drying Time ◽  
Transfer Resistance ◽  
Freeze Dried ◽  
Phenomenological Perspective

Freeze-dried berry fruits are generally consumed as they are, whole and without peeling or cutting, as the conservation of their original shape and appearance is often desired for the final product. However, usually, berries are naturally wrapped by an outer skin that imparts a barrier to vapor flow during freeze-drying, causing berry busting. Photo-sequence, experimental, and theoretical methodologies were applied to evaluate the application of CO2 laser microperforations to blueberry skin. Under the same set of freeze-drying conditions, blueberries with and without perforations were processed. The results showed that the primary drying time was significantly reduced from 17 ± 0.9 h for nontreated berries to 13 ± 2.0 h when nine microperforations per berry fruit were made. Concomitantly, the quality was also significantly improved, as the percentage of nonbusted blueberries at the end of the process increased from an average of 47% to 86%. From a phenomenological perspective, the analysis of the mass transfer resistance of nontreated fruits, in agreement with reported studies, showed a Type II curvature, with a sharp decrease at low time, followed by a linear increase. In contrast, blueberries with nine perforations depicted a Type III regime, with a saturation curvature toward the time axis. It was demonstrated that CO2-laser microperforation has high potential as a skin pretreatment for the freeze-drying of blueberries.

scholarly journals Effect of pretreatments on drying behavior of eggplant

2019 ◽  
Vol 17 (1) ◽  
pp. 105-109
Author(s):  
Md Junaeid Khan ◽  
Farjana Yeasmin ◽  
Md Nazrul Islam ◽  
Raju Ahmmed ◽  
Pabitra Chandra Das ◽  
...  
Keyword(s):  
Constant Temperature ◽  
Rate Constant ◽  
Hot Water ◽  
Effect Of Temperature ◽  
Constant Thickness ◽  
Drying Rate ◽  
Fresh Sample ◽  
Drying Time ◽  
Preservation Method ◽  
Drying Behavior

Eggplant is a familiar and admired vegetable in Bangladesh. It is a highly perishable vegetable and cannot be preserved long. Drying is an ancient preservation method used to extend shelf-life of fruits and vegetables. Different Pretreatments may affect the drying kinetics of foods. A study was conducted to evaluate how pretreatments affect the drying behavior of eggplant. Proximate composition of fresh eggplant was analyzed. The samples of constant thickness (8 mm) were dried at 50°C, 55°C and 60°C to determine the effect of temperature on drying rate constant, while for determining the effect of thickness on rate constant, eggplant slices of 4, 6 and 8 mm thicknesses were dried at a constant temperature of 55°C. It was observed that, drying rate decreased with the increase in thickness and the index ‘n’ was found to be 0.89 at 55°C. Under similar drying condition at constant thickness (8 mm), drying time showed an inverse relationship with temperature. The activation energy (Ea) was calculated as 3.242 Kcal/g-mole. Eggplant slices having the highest thickness (8 mm) were blanched at 70°C, 75°C and 80°C for 1, 2 and 2.5 minutes, respectively using hot water bath to determine the effective blanching time and temperature. It was observed that the samples blanched at 75°C and 80°C for 2 minute were enough to inactivate the enzymes. Pretreated (blanched, sulphited and blanched plus sulphited) eggplant slices having constant thickness (8 mm) were dried at constant temperature of 55°C. The drying time was influenced by pretreatments. The highest drying rate was observed for eggplant slices with blanched plus sulphited (5% KMS solution) samples while eggplant slices with 5%KMS solution dipped for 10 minutes showed the lowest drying rate. In case of fresh slices, drying time was lower than blanched and sulphited samples but higher than blanched plus sulphited samples. Pretreatment was also found effective on the color changes (preservation or degradation). Blanching gave a bright color compared to fresh sample but less bright compared to sulphited samples. In case of SO2 retention, blanched plus sulphited sample showed higher retention than sulphited sample. Sulphited sample retains 44.8 ppm SO2/100g of sulphited sample, while the blanched plus sulphited sample retains 280 ppm SO2/100 g of blanched plus sulphited sample. J. Bangladesh Agril. Univ. 17(1): 105–109, March 2019

Effect of Air Velocity and Temperature on the Drying Kinetics of Drumstick Leaves (Moringa Oleifera)

2012 ◽  
Vol 8 (4) ◽  
Author(s):  
Monica Premi ◽  
Harish Sharma ◽  
Ashutosh Upadhyay
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Moringa Oleifera ◽  
Moisture Diffusivity ◽  
Drying Kinetics ◽  
Drying Rate ◽  
Air Velocity ◽  
Drying Time ◽  
Effective Moisture ◽  
Kinetics Of

Abstract The present study examines the effect of air velocity on drying kinetics of the drumstick leaves in a forced convective dryer. The drumstick leaves were dried in the temperature range of 50–800 C, at different air velocity (Dv) of 0.5 and 1.3 m/s. The results indicated that drying temperature and air velocity are the factors in controlling the drying rate. Experimental data obtained for the samples for color, drying rate and drying time proved that air velocity of 1.3 m/s yielded the product superior in terms of both quality and energy efficiency as compared to the samples at 0.5 m/s. Activation energy for drumstick leaves dried with air velocity, 0.5 and 1.3 m/s was 12.50 and 32.74 kJ/mol respectively. The activation energy relates similarly with the effective moisture diffusivity which also increased with increase in air velocity and temperature.

Effects of Blanching Methods on Drying Kinetics of Oyster Mushroom

2009 ◽  
Vol 5 (4) ◽  
Author(s):  
Brijesh Srivastava ◽  
K. Padmeshore Singh ◽  
Wungshim Zimik
Keyword(s):  
Moisture Diffusivity ◽  
Exponential Model ◽  
Hot Water ◽  
Effective Moisture Diffusivity ◽  
Oyster Mushroom ◽  
Model Parameters ◽  
Drying Rate ◽  
Drying Time ◽  
Effective Moisture ◽  
Different Temperatures

Oyster mushroom was treated with hot water and steam blanching prior to drying in cabinet dryer. A hot air cabinet dryer was used for drying mushroom at 40, 50, 60, 70 and 80°C temperatures. Solid loss was observed to be 25.46% and 3.32% (wb) during hot water and steam blanching, respectively. Highest drying rate was observed for hot water blanched mushroom followed by unblanched and steam blanched mushroom. This leads to more drying time for the steam blanched mushroom followed by the unblanched and hot water blanched mushroom for the same level of drying. The drying data was modeled for exponential and Page's drying model. Page's model was found to be better than the exponential model for the prediction of drying rate. The value of the model parameters of the exponential model was found to be higher than that of Page's model. The effective moisture diffusivity (De) was determined at different temperatures and found to be maximum for the hot water blanched mushroom and minimum for the steam blanched mushroom. The effective moisture diffusivity (De) increased with increase in temperature. The activation energy of hot water blanched, unblanched and steam blanched mushroom was estimated to be 25.324, 17.113 and 21.165 kJ/mol, respectively.

Application of moisture transfer models to solids drying

2005 ◽  
Vol 219 (3) ◽  
pp. 235-244 ◽  
Author(s):  
E Kavak Akpinar ◽  
I Dincer
Keyword(s):  
Moisture Content ◽  
Moisture Transfer ◽  
Moisture Diffusivity ◽  
Drying Process ◽  
Drying Time ◽  
Air Temperatures ◽  
Moisture Transfer Coefficient ◽  
Drying Models ◽  
Good Agreement ◽  
Flow Velocities

In this paper, a comprehensive experimental investigation is conducted to measure the moisture content distributions within slab cut potato pieces during drying at temperatures of 60, 70, and 80°C and flow velocities of 1.0 and 1.5 m/s. Four drying models are employed to determine the drying process parameters (drying coefficient, lag factor, and half-drying time) and moisture transfer parameters (moisture diffusivity and moisture transfer coefficient), and to calculate moisture content distributions and compare them with extensive sets of experimental moisture data measured during the drying of slab cut potato slices at different drying air temperatures and flow velocities. Good agreement is obtained between the calculations and experimental measurements for the cases. In addition, experimental drying times are determined and compared with those obtained by the four different drying models. The results show that all four models are well able to determine the drying parameters and moisture content distributions. The experimental data and model findings are expected to be useful to the drying industry.

scholarly journals Effects of pretreatments on drying of Turkey berry in fluidized bed dryer

2021 ◽  
pp. 28-28
Author(s):  
R. Barathiraja ◽  
P. Thirumal ◽  
G. Saraswathy ◽  
I. Rahamathullah
Keyword(s):  
Fluidized Bed ◽  
Moisture Diffusivity ◽  
Drying Rate ◽  
Drying Time ◽  
Shrinkage Ratio ◽  
Fluidized Bed Dryer ◽  
Maximum Change ◽  
Physical Chemical ◽  
Pre Treatment ◽  
Berry Fruits

The influence of pre-treatment methods like physical, chemical, combined physical, and hybrid treatments on the Turkey berry fruits to enhance the water diffusion during drying was assessed due to the removal of a waxy layer on the peel. Pre-treated and untreated samples were dried at 70?C and 4 m/s of air flow in a fluidized bed dryer. Fruits pre-treated with combined abrasion and blanching have the lowest drying time, and favorable Vitamin-C content retention of 36%. The highest drying rate of 0.396 kg water/kg db min?1, maximum effective moisture diffusivity of 6.002 x 10-10 m2/s, and volumetric shrinkage ratio of 0.68 were obtained for fruits which undergone combined physical pre-treatment along with drying. The maximum change in color ?E = 14.75 and Chroma ?C = - 10.53 were obtained for the un-treated samples.

Drying kinetics and mechanical properties of low temperature microwave dried cashmere fibers

2020 ◽  
Vol 90 (23-24) ◽  
pp. 2745-2754
Author(s):  
Liuxiang Zhan ◽  
Yang Yang ◽  
Wan Li ◽  
Gaojun Wang ◽  
Yuling Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Moisture Diffusivity ◽  
Drying Rate ◽  
Drying Time ◽  
Microwave Vacuum Drying ◽  
Initial Stage ◽  
Drying Behavior ◽  
Drying Conditions ◽  
Drying Efficiency

Drying behavior of low temperature microwave vacuum–dried cashmere fibers and the drying rate at different times were investigated with different microwave powers, vacuum degrees and maximum drying temperatures to specify the optimum drying conditions in consideration of performance and drying efficiency in this study. The results show that higher microwave power can reduce the total drying time and significantly increase the drying rate in the initial stage. The degree of vacuum has a negligible effect on the drying behavior, and the influence of the three factors on effective moisture diffusivity is consistent with the drying behavior. Compared with hot-air-dried fibers, the mechanical properties of low temperature microwave-dried cashmere fibers could be significantly improved. In addition, excessive drying as delayed or overheated treatment will damage the fiber. The Page model is the most appropriate to describe the microwave vacuum drying of cashmere fibers.

scholarly journals Study on drying kinetics of summer onion

2015 ◽  
Vol 39 (4) ◽  
pp. 661-673 ◽  
Author(s):  
Md Masud Alam ◽  
Md Nurul Islam ◽  
Md Nazrul Islam
Keyword(s):  
Activation Energy ◽  
Mass Transfer ◽  
Rate Constant ◽  
Variable Temperature ◽  
Air Flow ◽  
Drying Kinetics ◽  
Effect Of Temperature ◽  
Drying Rate ◽  
External Resistance ◽  
Kinetics Of

The present study was concerned with the kinetics of drying of summer onion. Drying was done in a mechanical dryer at constant air flow using blanched and unblanched onion with variable temperature (52, 60 and 680C) and thickness (3, 5 and 7 mm). Drying rate was increased with increase of temperature and decreased with the increase in thickness in blanched and unblanched onion. Blanched onion showed higher drying rate than unblanched onion. Drying rate constant and thickness can be expressed as power low equations. The value of index “n” were found to be 1.277 and 0.845 for onion indicating that the external resistance to mass transfer was highly significant. The effect of temperature on diffusion co-efficient follows an Arrhenius type relationship. The activation energy (Ea) for diffusion of water was found 5.781 Kcal/g-mole for unblanched and 2.46 Kcal/g-mole for blanched onion when onions were dried in mechanical dryer. DOI: http://dx.doi.org/10.3329/bjar.v39i4.22545 Bangladesh J. Agril. Res. 39(4): 661-673, December 2014

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