The kinetics of thin-layer drying and modelling for mango slices and the influence of differing hot-air drying methods on quality

Microwave drying is a promising and effective way to drying and upgrading lignite. The influence of temperature (100–140 °C) and microwave power levels (500–800 W) on thin-layer drying characteristics of Zhaotong lignite under microwave irradiation were investigated. Fourteen thin-layer drying models were used to analyze the microwave drying process while six thin-layer drying models were used to analyze the hot-air drying process. The microwave drying processes at all temperature (100–140 °C) or low microwave power levels (500–700 W) exhibited four periods: a warm-up period, a short constant period, the first and second falling rate period, while one falling rate period was found during hot-air drying. The effective diffusion coefficient of lignite were calculated and it increases with increasing temperature and microwave power levels. During microwave drying, the two-term exponential model is the most suitable model for all applied conditions, while the Modified Page model is the most suitable model to describe the hot-air drying experiments. The apparent activation energy were determined from Arrhenius equation and the values for the first and second falling rate period are 3.349 and 20.808 kJ·mol−1 at different temperatures, while they are 13.455 and 19.580 W·g−1 at different microwave power levels. This implies the apparent activation energy is higher during the second falling rate period, which suggest that the dewatering of absorbed water is more difficult than capillary water. The value of apparent activation energy in hot-air drying is between the first and second falling rate period of microwave drying. Results indicate that microwave drying is more suitable to dewatering free water and capillary water of lignite.

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Application of Computational Intelligence in Describing the Drying Kinetics of Persimmon Fruit (Diospyros kaki) During Vacuum and Hot Air Drying Process

Processes ◽

10.3390/pr8050544 ◽

2020 ◽

Vol 8 (5) ◽

pp. 544 ◽

Cited By ~ 2

Author(s):

Alfadhl Yahya Khaled ◽

Abraham Kabutey ◽

Kemal Çağatay Selvi ◽

Čestmír Mizera ◽

Petr Hrabe ◽

...

Keyword(s):

Thin Layer ◽

Computational Intelligence ◽

Drying Kinetics ◽

Support Vector ◽

Hot Air Drying ◽

Air Drying ◽

Persimmon Fruit ◽

Hot Air ◽

Computational Intelligence Methods ◽

Kinetics Of

This study examines the potential of applying computational intelligence modelling to describe the drying kinetics of persimmon fruit slices during vacuum drying (VD) and hot-air-drying (HAD) under different drying temperatures of 50 °C, 60 °C and 70 °C and samples thicknesses of 5 mm and 8 mm. Kinetic models were developed using selected thin layer models and computational intelligence methods including multi-layer feed-forward artificial neural network (ANN), support vector machine (SVM) and k-nearest neighbors (kNN). The statistical indicators of the coefficient of determination (R2) and root mean square error (RMSE) were used to evaluate the suitability of the models. The effective moisture diffusivity and activation energy varied between 1.417 × 10−9 m2/s and 1.925 × 10−8 m2/s and 34.1560 kJ/mol to 64.2895 kJ/mol, respectively. The thin-layer models illustrated that page and logarithmic model can adequately describe the drying kinetics of persimmon sliced samples with R2 values (>0.9900) and lowest RMSE (<0.0200). The ANN, SVM and kNN models showed R2 and RMSE values of 0.9994, 1.0000, 0.9327, 0.0124, 0.0004 and 0.1271, respectively. The validation results indicated good agreement between the predicted values obtained from the computational intelligence methods and the experimental moisture ratio data. Based on the study results, computational intelligence methods can reliably be used to describe the drying kinetics of persimmon fruit.

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Thin Layer Modelling of Microwave-Convective Drying of Tomato Slices

International Journal of Food Engineering ◽

10.1515/ijfe-2012-0205 ◽

2013 ◽

Vol 9 (1) ◽

pp. 75-90 ◽

Cited By ~ 13

Author(s):

Tilahun S. Workneh ◽

Moruf O. Oke

Keyword(s):

Activation Energy ◽

Thin Layer ◽

Microwave Power ◽

Hot Air Drying ◽

Air Drying ◽

Hot Air ◽

Thin Layer Drying ◽

Rate Period ◽

Air Ventilation ◽

Best Fit

AbstractThe thin layer drying behaviour of tomato slices dried using microwave power densities of 1.13, 2.08 and 3.11 W/g combined with air ventilation (50°C) and hot air drying at 40, 50, 70 and 80°C was investigated. The tomato slice dried faster when subjected to microwave heating coupled with hot air ventilation. Drying time decreased considerably with increase in microwave power density and with increase in hot air temperature. Drying took place in a constant rate period followed by the falling rate period after a short heating period. The drying data were fitted to Newton (Lewis), Page, Henderson and Pabis, Logarithmic, Wang and Singh and Parabolic equations. The Parabolic model (R2 = 0.9999; χ2 = 0.0085; MBE = 0.0182 and RMSE = 0.0691) gave the best fit to predict the hot air ventilation drying of tomato slices while the Logarithmic model (R2 = 0.9951; χ2 = 0.0024; MBE = −0.0319 and RMSE = 0.0477) gave the best fit for microwave-assisted hot air drying of tomato slices. The values of the effective diffusivity coefficients of the tomato slices varied between 1.68 × 10–9 and 5.22 × 10–8 m2/s while the activation energy was 27.09 kJ/mol. The lower activation energy indicates that drying of tomato slices requires less energy and is hence a cost and energy-saving method. Microwave drying at 1.13 and 2.08 W/g maintained superior colour quality of the tomato slices.

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Experimental Investigation on the Effect of Pre-Treatments on Thin Layer Drying and Quality Characteristics of Green Mangoes in Forced Convection Hot Air Drying

International Journal of Current Microbiology and Applied Sciences ◽

10.20546/ijcmas.2019.806.371 ◽

2019 ◽

Vol 8 (06) ◽

pp. 3112-3124 ◽

Cited By ~ 1

Author(s):

Mayank Mishra ◽

R.N. Shukla ◽

P. Kandasami ◽

Boris Huirem

Keyword(s):

Experimental Investigation ◽

Thin Layer ◽

Forced Convection ◽

Quality Characteristics ◽

Hot Air Drying ◽

Air Drying ◽

Hot Air ◽

Thin Layer Drying

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Supercritical CO2 Extraction of Phytocompounds from Olive Pomace Subjected to Different Drying Methods

Molecules ◽

10.3390/molecules26030598 ◽

2021 ◽

Vol 26 (3) ◽

pp. 598

Author(s):

Graziana Difonzo ◽

Antonella Aresta ◽

Pietro Cotugno ◽

Roberta Ragni ◽

Giacomo Squeo ◽

...

Keyword(s):

Olive Oil ◽

Freeze Drying ◽

Oil Production ◽

Production Costs ◽

Drying Methods ◽

Olive Pomace ◽

Hot Air Drying ◽

Air Drying ◽

Hot Air ◽

Pharmaceutical Industries

Olive pomace is a semisolid by-product of olive oil production and represents a valuable source of functional phytocompounds. The valorization of agro-food chain by-products represents a key factor in reducing production costs, providing benefits related to their reuse. On this ground, we herein investigate extraction methods with supercritical carbon dioxide (SC-CO2) of functional phytocompounds from olive pomace samples subjected to two different drying methods, i.e., freeze drying and hot-air drying. Olive pomace was produced using the two most common industrial olive oil production processes, one based on the two-phase (2P) decanter and one based on the three-phase (3P) decanter. Our results show that freeze drying more efficiently preserves phytocompounds such as α-tocopherol, carotenoids, chlorophylls, and polyphenols, whereas hot-air drying does not compromise the β-sitosterol content and the extraction of squalene is not dependent on the drying method used. Moreover, higher amounts of α-tocopherol and polyphenols were extracted from 2P olive pomace, while β-sitosterol, chlorophylls, and carotenoids were more concentrated in 3P olive pomace. Finally, tocopherol and pigment/polyphenol fractions exerted antioxidant activity in vitro and in accelerated oxidative conditions. These results highlight the potential of olive pomace to be upcycled by extracting from it, with green methods, functional phytocompounds for reuse in food and pharmaceutical industries.

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