Experimental Assessment of Energy and Mass Transfer in Microwave Drying of Fig Fruit

Authors
F. Sharifian
A. Mohammad Nikbakht
A. Arefi
A. Modarres Motlagh
Department of Mechanical engineering of biosystems, Faculty of Agriculture, Urmia University, Urmia, Iran.
Abstract
Energy and mass transfer investigations in thermal processing of fruits serve as a breakthrough in the design and scale up of drying systems. Diffusivity characteristics and specific energy consumption for drying of fig fruit in a laboratory scale microwave dryer were assessed. Several intervals for microwave power intensity including 0.5, 1, 1.5, 2, and 2.5 W g-1, and 6 levels of power on-off stated as pulsing ratios of 1.5, 2, 2.5, 3, 3.5, and 4 were employed. The results showed that the drying rate decreased with the pulsing ratio and increased with microwave power intensity. Effective moisture diffusivity as an indicator of mass transfer was obtained to be higher at elevated microwave power intensities. Also, increased pulsing ratios had a reducing effect on moisture diffusivity. Using 2nd law of Fick, moisture diffusivity was calculated to be varying from 5.93E-10 to 1.42E-08 m2 s-1 depending on the experimental conditions. Furthermore, the activation energy of fig fruit was obtained to be in the range of 60.094 to 92.189 kJ mol-1. Specific energy consumption variations showed a positive correlation with pulsing ratio and drying time. However, due to the dependence of energy consumption on MW power intensity, a multiple regression analysis with R2 of 0.968 was developed.

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Subjects

1. Al-Harahsheh, M., Al-Muhtaseb, A. and Magee, T. R. A. 2009. Microwave Drying Kinetics of Tomato Pomace: Effect of Osmotic Dehydration. Chem. Eng. Process., 48: 524-31.
2. Altan, A. and Maskan, M. 2005. Microwave Assisted Drying of Short-cut (Ditalini) Macaroni: Drying Characteristics and Effect of Drying Processes on Starch Properties. Food Res. Int., 38: 787-96.
3. AOAC. 1990. Official Methods of Analysis. Association of Official Analytical Chemists, Arlington, VA.
4. Babalis, S. J., Papanicolaou, E., Kyriakis, N. and Belessiotis, V. G. 2006. Evaluation of Thin-layer Drying Models for Describing Drying Kinetics of Figs (Ficus carica). J. Food Eng., 75: 205-14.
5. Chayjan, R. A., Peyman, M. H., Esna-Ashari, M. and Salari, K. 2011. Influence of Drying Conditions on Diffusivity, Energy and Color of Seedless Grape after Dipping Process. AJCS, 5(1): 96-103.
6. Crank, J. 1975. The Mathematics of Diffusion. Second Edition, Clarendon Press, Oxford.
7. Darvishi, H., Khoshtaghaza, M. H., Najafi, G. and Nargesi, F. 2013. Mathematical Modeling of Green Pepper Drying in Microwave-Convective Dryer. J. Agr. Sci. Tech., 15: 457-465.
8. Doymaz, I. 2005. Sun Drying of Fig: An Experimental Study. J, Food Eng., 71: 403-7.
9. Doymaz, I. 2012. Evaluation of some Thin-layer Drying Models of Persimmon Slices (Diospyros kaki L.). Energy Convers. Manage., 56: 199-205.
10. FAO. 2010. FAO Stat: Agriculture Data. < http://faostat.fao.org/site/339/default.aspx> [Accessed March, 2012].
11. Gunasekaran, S. 1999. Pulsed Microwave-vacuum Drying of Food Materials. Dry. Technol., 17(3): 395-412.
12. Hashemi, G., Mowla, D. and Kazemeini, M. 2009. Moisture Diffusivity and Shrinkage of Broad Beans during Bulk Drying in an Inert Medium Fluidized Bed Dryer Assisted by Dielectric Heating. J. Food Eng., 92: 331-8.
13. Imre, L. 2006. Solar Drying, In: “Handbook of Industrial Drying”, (Eds.): Mujumdar, A. S.. 3rd Edition, CRC Press, Taylor & Francis Group, New York.
14. Jayaraman, K. S. and Das Gupta, D. K. 2006. Drying of Fruits and Vegetables. In: “Handbook of Industrial Drying”, (Eds.): Mujumdar, A. S.. 3rd Edition, CRC Press, Taylor & Francis Group, New York.
15. Karaaslan, S. N. and Tunçer, Í. K. 2008. Development of a Drying Model for Combined Microwave-fan-assisted Convection Drying of Spinach. Biosyst. Eng., 100: 44-52.
16. Knoerzer, K., Regier, M. and Schubert, H. 2006. Microwave Heating: A New Approach of Simulation and Validation. Chem. Eng. Technol., 9(7): 796-801.
17. Kudra, T. and Mujumdar, A. S. 2006. Special Drying Techniques and Novel Dryers. In: “Handbook of Industrial Drying”, (Eds.): Mujumdar, A. S.. 3rd Edition, CRC Press, Taylor & Francis Group, New York.
18. Kumar, N., Sarkar, B. C. and Sharma, H. K. 2011. Effect of Air Velocity on Kinetics of Thin Layer Carrot Pomace Drying. Food Sci. Technol. Int., 17(5): 459-469.
19. Marinos-Kouris, D. and Maroulis, Z. B. 2006. Transport Properties in the Drying of Solids. In: “Handbook of Industrial Drying”, (Eds.): Mujumdar, A. S.. 3rd Edition, CRC Press, Taylor & Francis Group, New York.
20. Mohsenin, N. N. 1986. Physical Properties of Plant and Animal Materials. 2nd Revised and Updated Edition, Gordon and Breach Sci. Pub., New York.
21. Premi, M. Sharma, H. and Upadhyay, A. 2012. Effect of Air Velocity on the Drying Kinetics of Drumstick Leaves (Moringa oleifera). Int. J. Food Eng., 8(4): Article 13.
22. Rafiee, Sh., Kashaninejad, M., Keyhani, A. R. and Jafari, A. 2009. Pistachio Nut (Ohadi Variety) Mass Transfer Simulation during Process of Drying Using Finite Element Method. J. Agri. Sci. Tech., 11: 137-146.
23. Sarimeseli, A. 2011. Microwave Drying Characteristics of Coriander (Coriandrum sativum L.) Leaves. Energy Convers. Manage., 52: 1449-53.
24. Sharma, G. P. and Prasad, S. 2006. Specific Energy Consumption in Microwave Drying of Garlic Cloves. Ener., 31: 1921-6.
25. Wang, J. and Sheng, K. 2006. Far-infrared and Microwave Drying of Peach. LWT-Food Sci. Technol., 39: 247-55.
26. Wang, J., Wang, J. S. and Yu, Y. 2007. Microwave drying Characteristics and Dried Quality of Pumpkin. Int. J. Food Sci. Technol., 42: 148-56.
27. Xanthopoulos, G., Yanniotis, S. and Lambrinos, G. R. 2010. Study of the Drying Behaviour in Peeled and Unpeeled Whole Fig. J. Food Eng., 97: 419-24.
28. Zheng, W.C., Shi, Y. X. and Da, W. S. 2004. Microwave-vacuum Drying Kinetics of Carrot Slices. J. Food Eng., 65: 157-64.
Journal of Agricultural Science and Technology
Volume 17, Issue 7
November and December 2015
Pages 1695-1705