Characterisation of Potato Slices During Drying: Density, Shrinkage, and Thermodynamic of Sorption

Author(s):  
Saber Chemkhi ◽  
Féthi Zagrouba

In this study, we are interested in a thermo-physic characterisation during hot air drying of one food product: the potato. The drying kinetics of potato slices are determined at three temperatures and three air velocities. The evolution of the density and the material shrinkage are determined and commented. We finish with the equilibrium moisture relations for the product. From experimental data, we have modeled the desorption isotherms using the GAB model. From the results, we notice that this model perfectly describes the measures with correlation factors superior to 97%. A thermodynamic analysis of isotherms has been made: the heat of sorption is calculated; the entropy of sorption has also been determined and has been commented.

2007 ◽  
Vol 79 (4) ◽  
pp. 1460-1466 ◽  
Author(s):  
A. Vega ◽  
P. Fito ◽  
A. Andrés ◽  
R. Lemus

2020 ◽  
Vol 14 ◽  
Author(s):  
Abhishek Dasore ◽  
Tarun Polavarapu ◽  
Ramakrishna Konijeti ◽  
Naveen Puppala

Author(s):  
Dan Huang ◽  
Yuchao Tao ◽  
Wei Li ◽  
S. A. Sherif ◽  
Xiaohong Tang

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.


Author(s):  
Kricelle M. Deamici ◽  
Lucas C. de Oliveira ◽  
Gabriela S. da Rosa ◽  
Elizangela G. de Oliveira

ABSTRACT The aim of this study was to obtain the equilibrium moisture content of grape (variety ‘Tannat’) pomace through desorption isotherms, to evaluate the drying kinetics, determine the coefficient of effective diffusivity and physico-chemically characterize the grape pomace and the product obtained after drying. The desorption isotherms were determined at 50, 60 and 70 ºC and the experimental data were fitted using the GAB model (Gugghenheim, Anderson and de Boer). Drying was evaluated using a 22 factorial experimental design with three center points and effective diffusivity was obtained through the diffusion model of Fick’s second law. The grape pomace was characterized regarding the contents of moisture, protein, carbohydrates, lipids, ash and dietary crude fiber. The obtained isotherms showed sigmoid shape and the experimental data fitted well to the GAB model. The drying curves showed only a decreasing rate period. The effective diffusivity values were within the range for organic materials. Dry grape pomace showed high contents of protein and fiber and can be used in the development of new products, in order to increase the nutritional content and add value to this byproduct.


2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Ernest Abano

Microwave and steam blanching as pretreatments to hot air drying of orange-fleshed sweet potato (OFSP) were studied. The air-drying experiment was performed at constant temperature of 70°C and airflow of 1.0 m/s. The effective moisture diffusivity varied from 1.5 × 10 − 9 to 4.4 × 10 − 9 m2/s, and 1.1 × 10 − 10 to 7.9 × 10 − 10 m2/s, for the microwave and blanched assisted hot air drying, respectively. The activation energy obtained for the various microwave-assisted hot air drying was 29.1 W/mm for 4 min, 68.1 W/mm for 3 min, and 79.7 W/mm for 2 min. Ascorbic acid degradation and formation of brown pigments in the OFSP slices were lower in microwave than in steam blanch-assisted drying. Microwave-assisted drying of OFSP is best governed by Page model, M R = exp − k t n , while the blanch-assisted followed the logarithmic model, M R = a   exp − k t + c . To produce better quality OFSP flour, it is recommended to cut the tubers into 3 mm slices, microwave at a power of 630 W for 2 min or blanch for 1 min, 43 seconds prior to hot air drying.


2013 ◽  
Vol 844 ◽  
pp. 154-157
Author(s):  
Warit Werapun ◽  
Yutthapong Pianroj ◽  
Pinpong Khongchana

This study investigated the drying kinetics of the natural rubber sheets under hot air drying, with various heat sources, and included modeling of the kinetics. The heat was generated by combustion, either of charcoal briquettes from coconut shell (biomass) or of liquid petroleum gas (LPG). The hot air entering the drying chamber had its initial temperature controlled at 40, 50, or 60 Centigrade. Five rubber sheets within the chamber were observed during their drying. Howerver, in the case of biomass, the fuctuation of temperature due to charcoal adding. Therfore, the non-linear regression analysis was performed only LPG data with a Weibull distribution and a Modified Handerson and Pabis. They represented the drying kinetics with parametric fits; moreover, an effective diffusion coefficient was determined for each experimental condition.


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