Study of the Drying Rate and Colour Kinetics during Stepwise Air-Drying of Apricot Halves

2019 ◽  
Vol 15 (5-6) ◽  
Author(s):  
G. Xanthopoulos ◽  
A. Athanasiou ◽  
A. Sempou ◽  
D. Lentzou ◽  
Ch. Templalexis ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Drying Rate ◽  
Temperature Profiles ◽  
Air Drying ◽  
Browning Index ◽  
Colour Kinetics ◽  
Levenberg Marquardt ◽  
Rate Period ◽  
Step Down ◽  
Kinetics Of

AbstractThe drying rate and colour kinetics of apricot halves were studied during stepwise air-drying compared to continuous drying. The tested stepwise temperature profiles exhibited two successive falling rate periods, which differed from the drying rate period of the constant drying temperature profile. Three chromatic indices, namely browning index, chroma and hue were analysed. The analysis showed that treatment with ascorbic acid was more effective during the step up temperature profile, whilst its antioxidant activity was lost during the step down temperature profile due to the initially used high drying temperatures. The chromatic indices were described by a modified kinetic model, the parameters of which were estimated by the Levenberg–Marquardt optimization algorithm and in all cases was derived R2adj≥ 0.88 and MRD < 4.88%.

Effect of Pre-Treatment on the Drying Characteristics and Kinetics of Okra (Abelmoschus esculetus (L.) Moench) Slices

2009 ◽  
Vol 5 (2) ◽  
Author(s):  
Olajide Sobukola
Keyword(s):  
Air Temperature ◽  
Sample Thickness ◽  
Hot Water ◽  
Drying Rate ◽  
Diffusivity Coefficient ◽  
Drying Characteristics ◽  
Rate Period ◽  
Pretreatment Conditions ◽  
Air Dryer ◽  
Kinetics Of

The effects of air temperature (50, 60 and 70°C), sample thickness (2, 4 and 6mm) and pretreatment conditions (hot water blanching, 1 and 3% sodium metabisulphite solutions) on the drying characteristics and kinetics of okra were investigated using a convective hot air dryer at a flow rate of 1.5m/s. It was observed that pretreatment conditions, sample thickness and drying air temperature significantly (P<0.05) affected drying rate. Drying rate increases as temperature of drying air increases from 50 to 70°C. The drying curve for all experiments occurred in the falling rate period with no constant rate period. Three thin layer drying models (Page, modified Page I and Wang and Singh) were evaluated using coefficient of determination (R2), root mean square error (RMSE) and the reduced chi square (?2). The three models can appropriately describe the drying kinetics of okra slices considering the different experimental conditions. The effective diffusivity was determined using the Fick’s model and was observed to vary between 1.125x10-8 – 9.93x10-9m2/s and 1.165x10-8 – 7.131x10-9 m2/s for treated and untreated samples. The Arrhenius-type relationship describes the temperature dependence of diffusivity coefficient and was determined to be 16.749kJ/mol and 22.437kJ/mol for treated and untreated samples respectively.

scholarly journals The effect of drying on the mechanical properties and structure of biodegradable films

2018 ◽  
Author(s):  
Gabriela Silveira da Rosa ◽  
Sai Vanga ◽  
Yvan Gariepy ◽  
Vijaya Raghavan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Convective Drying ◽  
Vacuum Drying ◽  
Drying Rate ◽  
Biodegradable Films ◽  
Film Forming ◽  
Rate Period ◽  
Bovine Gelatin ◽  
Kinetics Of

The aim of this study was to investigate the effect of convective and vacuum drying on properties of biodegradable films. The film-forming solutions were prepared with bovine gelatin and carrageenan. The films solutions were dried in convective and vacuum dryers at temperatures of 40, 50 and 60 oC. The results of convective drying kinetics of biofilms showed a constant drying rate period followed by a falling drying rate period. The results of thickness showed dependence with moisture content present in films.Carrageenan films showed promising results, with high values of tensile strength and elongation for convective drying at 60 oC. Keywords: gelatin; carrageenan; drying; biofilm 

Heat Transfer Characteristics and Kinetics of Camellia oleifera Seeds During Hot-Air Drying

2019 ◽  
Vol 12 (3) ◽  
Author(s):  
Dan Huang ◽  
Yuchao Tao ◽  
Wei Li ◽  
S. A. Sherif ◽  
Xiaohong Tang
Keyword(s):  
Heat Transfer ◽  
Camellia Oleifera ◽  
Heat Transfer Characteristics ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Drying Characteristics ◽  
Hot Air ◽  
Rate Period ◽  
Kinetics Of

Abstract The heat transfer characteristics and kinetics of Camellia oleifera seeds under hot-air drying were investigated at different temperatures (40, 60, and 80 °C) and loading densities (0.92, 1.22, and 1.52 g/cm2) with a constant air velocity of 1 m/s. Twelve common drying kinetic models were selected to fit the experimental data. The most suitable model was chosen to describe the hot-air drying process of C. oleifera seeds and help in its optimization. The results showed that the drying temperature has a significant influence on the hot-air drying characteristics of C. oleifera seeds. As the drying air temperature increases, the drying time decreases. The effect of the loading density on the drying characteristics of C. oleifera seeds is much smaller than that of temperature. With the increase in the loading density, the drying time slightly increases. The hot-air drying curve of C. oleifera seeds consists of a very short acceleration rate period at the beginning and a long falling rate period, indicating that the drying of C. oleifera seeds is mainly controlled by the diffusion of moisture inside the material. An effective moisture diffusion coefficient of C. oleifera seeds was estimated to range from 0.81256 × 10−9 to 3.28496 × 10−9 m2/s within the temperature range studied. The average activation energy was 28.27979 kJ/mol. The logarithmic model was found to be the best model to describe the kinetics of hot-air drying of C. oleifera seeds.

scholarly journals Effects of low temperature drying processing on longan fruit

2018 ◽  
Vol 192 ◽  
pp. 03024
Author(s):  
Thadchapong Pongsuttiyakorn ◽  
Pachareeporn trusphimai ◽  
Pitikhate Sooraksa ◽  
Pimpen Pornchaloempong
Keyword(s):  
Drying Rate ◽  
Suitable Model ◽  
Moisture Removal ◽  
Browning Index ◽  
Air Temperatures ◽  
Constant Rate ◽  
Drying Techniques ◽  
Rate Period ◽  
Low Temperature Drying

In this study, the single-stage drying in tray dryer at air temperatures of 40, 50, 60, 70 and 80°C is modelled and investigated. The longan fruits, E-dor variety, are peeled and seeded before testing. The drying rate is significantly influenced by the drying techniques and temperatures. Drying rats are initialized adjustment constant rate periods at 60 70 and 80°C. The rate of moisture removal is rapidly changed drastically during the falling rate period. The Midilli model with high R2 and low χ2 and RMSE is the most suitable model for predictability of longan drying. Variation rates of quality of the water activity, the shrinkage, and the browning index are also reported.

scholarly journals Hot air drying characteristics and nutrients of apricot armeniaca vulgaris lam pretreated with Radio Frequency(RF)

2018 ◽  
Author(s):  
X.L. Huang ◽  
M.C. Peng ◽  
J.X. Liu ◽  
Y. Lei ◽  
X.J. Yang ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Drying Rate ◽  
Hot Air Drying ◽  
Air Drying ◽  
Drying Characteristics ◽  
Hot Air ◽  
Rate Period ◽  
Pretreatment Time

Apricot pretreated with RF and then dried with convective hot air at 65℃, 3.0m/s in this research. RF pretreatment time of 20, 30, 40 and 50min were chosen. Results showed that, there is only falling rate period during apricot hot air drying, and the drying rate of apricot is improved significantly; Herdenson and Pabis model is suitable for apricot hot air drying; retentions of flavonoids, polyphenols and Vc in dried apricot were higher than those of fresh apricot; when RF treating time was chosen 30mins, nutrients retentions of Vc, flavonoid and polyphenols were 0.9543mg/100g, 5.4089mg/100g and 7.3382mg/100g, separately.   Keywords: apricot fruit, hot air drying, drying rate, nutrients, radio frequency 

scholarly journals İncirin Sıcak Hava ve Mikrodalga Destekli Köpük Kurutma Yöntemi ile Kurutulması

2019 ◽  
Vol 7 (2) ◽  
pp. 291
Author(s):  
Mehmet Koç ◽  
Feyza Elmas ◽  
Emine Varhan
Keyword(s):  
Diffusion Coefficient ◽  
Effective Diffusion ◽  
Microwave Drying ◽  
Drying Rate ◽  
Drying Process ◽  
Hot Air Drying ◽  
Air Drying ◽  
Hot Air ◽  
Rate Period ◽  
Foam Thickness

In this study, the drying process of fig foam was carried out with hot air (60, 70, 80°C) and microwave (100, 300, 600 W) and the effect of drying process parameters and foam thickness on drying kinetics was investigated. The drying process was carried out only falling drying rate period and no constant drying rate period was observed. The drying times of the microwave drying were lower than the drying times of hot air drying due to the volumetric heating in addition to the large evaporation area on the foam surfaces. Drying times were shortened by increasing the temperature and microwave power whereas drying time increased with increasing foam thickness. Experimental drying data were placed in semi-empirical models of the 2. Fick's diffusion equation to determine kinetic parameters. Among them, it was found that Wang and Singh and Logarithmic models were better fitted for microwave and hot air drying respectively. The effective diffusion coefficient values for microwave and hot air drying varied between 9.94×10-10-405.69×10-10, 13.26×10-10-26.65×10-10 m2·s-1, respectively. Effective diffusion coefficient values increased with increasing temperature, microwave power and foam thickness. High thickness supported the diffusion process by convection of heat due to the increase in gaps in the structure. Activation energy which calculated with Arrhenius equation was varied from 2.195-2.379 W·g-1 for microwave drying and 12.952-21.426 kJ·mol-1 for hot air drying.

scholarly journals Convective air drying of brown seaweed Bifurcaria bifurcata in thin layer configuration

2018 ◽  
Author(s):  
Ramón Moreira ◽  
Santiago Arufe-Vilas ◽  
Jorge Sineiro ◽  
Francisco Chenlo
Keyword(s):  
Brown Seaweed ◽  
Drying Kinetics ◽  
Drying Rate ◽  
Transfer Coefficients ◽  
Air Drying ◽  
Bifurcaria Bifurcata ◽  
Kinetics Modelling ◽  
Effective Coefficients ◽  
Rate Period ◽  
Critical Moisture

Air drying kinetics of Bifurcaria bifurcata brown seaweed at 35, 50, 60 and 75°C were determined. Experimental drying data were modelled using two-parameter Page model (n, k). Page parameter n was constant (1.28) at tested temperatures, but k increased significantly with drying temperature from 35 to 60ºC and was invariant at higher temperatures (up to 75ºC). Drying experiments allowed the determination of the critical moisture content of seaweed (1.6 ± 0.2 kg water (kg d.b.)−1). Mass transfer coefficients during constant drying rate period and effective coefficients of water diffusion during falling drying rate period were evaluated, assuming cyclindrical geometry and considering volumetric shrinkage. Keywords: algae, diffusivity, drying kinetics, modelling, shrinkage  

scholarly journals Empirical Modeling of Hot Air-Drying Kinetics of Horseradish Dehydration

2020 ◽  
Vol 4 (1) ◽  
pp. 44
Author(s):  
Mukesh Guragain ◽  
Pranabendu Mitra
Keyword(s):  
Moisture Content ◽  
Empirical Models ◽  
Drying Kinetics ◽  
Hot Air Drying ◽  
Air Drying ◽  
Drying Temperature ◽  
Hot Air ◽  
Rate Period ◽  
Drying Conditions ◽  
Kinetics Of

The preservation of perishable horseradish crop is essential to increase the shelf-life and supply year-round. Hot air-drying method is commercially viable for preserving fruits and vegetables. However, drying conditions such as drying temperature affect the drying kinetic and the final quality of dried products. It is necessary to understand how drying temperature and blanching affect the drying kinetics of horseradish for the prediction of the right drying conditions. The objective of this study was to investigate the hot air-drying kinetics by fitting commonly used five empirical models to establish right hot air-drying conditions for drying of horseradish. The unblanched (control, C) and blanched (B) horseradish slices were dried at 50, 70 and 85℃ until reaching to an equilibrium moisture content (db). The moisture reduction data were collected at certain intervals and the moisture content data were converted to moisture ratio (MR). The MR data were used to predict the drying kinetics of horseradish drying using five empirical models. The results indicated that drying kinetics followed the constant drying rate period and falling rate period for all three drying temperatures. The five tested models were able to predict the drying kinetics with R2 (0.96-0.99) and RMSE (0.01-0.06) depending on the models and blanching. However, diffusion approach model was the best fitted model securing the highest R2 and the lowest RMSE. The findings of this research are expected to be significantly important for horseradish drying effectively.

Drying Kinetics of Osmotically Pre-Treated Plum Tomato Pieces

2008 ◽  
Vol 4 (8) ◽  
Author(s):  
Marianne S Brooks ◽  
Abdel E Ghaly ◽  
Nabiha H Abou El-Hana
Keyword(s):  
Sample Size ◽  
Cell Walls ◽  
Moisture Diffusivity ◽  
Drying Kinetics ◽  
Moisture Ratio ◽  
Air Drying ◽  
Rate Period ◽  
Pre Treatment ◽  
Kinetics Of ◽  
Over Time

The air-drying kinetics of plum tomato pieces pre-treated with different osmotic solutions were investigated. Four pre-treatment solutions (comprised of salt, sugar and/or calcium lactate), three sample geometries (halves, quarters and eighths) and two air-drying temperatures (55 and 65°C) were studied. In general, the rate of drying over time appeared to fit an exponential curve (R2 values between 0.74 and 0.99). A closer look at the data indicated that the rate of drying appeared to follow two separate falling rate periods. The change from one falling rate period to another was observed for samples at a transition moisture ratio of ~ 0.2, for all geometries and temperatures. Thus, modeling the process was improved by including the two falling rate periods. The drying constant (K) for the two falling rate periods ranged between 0.05 to 0.3 h-1. Moisture diffusivity values ranged from 2.5 x 10-9 to 9 x 10-9 m2 s-1 and were relatively constant during the first falling rate period. During the second falling rate period, the diffusivity increased as the moisture ratio decreased, though this change was less pronounced as the sample size decreased from halves to eighths. The untreated samples had lower diffusivities than those with osmotic pre-treatment but there were no differences amongst the various pre-treatment solutions. In general, moisture diffusivities showed a dependence on the sample size, as the larger tomato samples had higher values of diffusivity. The greater diffusivity seen in the larger samples may be due to the collapse of cell walls in the skin.

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