Comparative analysis of drying coffee beans using microwave and conventional oven
Keywords:grain drying, drying curve, diffusion coefficient, microwave drying
This article reports a comparative study of experimental results obtained during the drying of Castilla-variety coffee beans from Santander, Colombia. They were performed by two means: thermal and electromagnetic radiation. Twenty experiments were carried out, ten tests in a microwave cavity at 2,450 MHz-1,080W, and ten tests using a conventional electric oven with temperature controlled at 50±2oC. Experiments were made using samples of coffee beans with parchment, without parchment, and of the only-parchment. For each sample, dimensionless moisture ratio and diffusion coefficients were determined, according to the second law of Fick. We found that the diffusion coefficient of the samples dried in a microwave cavity was twenty-two times higher than the diffusion coefficient of samples dried with thermal radiation. Likewise, it was observed that samples in conventional oven showed a uniform temperature, in contrast with those heated by microwave radiation. Such results are useful for designing hybrid systems for drying coffee beans.
S. O. Nelson, “Potential agricultural applications for rf and microwave energy,” Transactions of the ASAE, vol. 30, no. 3, 1987. [Online]. Available: https://doi.org/10.13031/2013.30480
W. Radajewski, P. Jolly, and G. Y. Abawi, “Optimization of solar grain drying in a continuous flow dryer,” Journal of Agricultural Engineering Research, vol. 38, no. 2, 1987. [Online]. Available: https://doi.org/10.1016/0021-8634(87)90125-9
U. S. Shivhare, V. G. S. Raghavan, and R. G. Bosisio, “Microwave drying of corn I. equilibrium moisture content,” Transactions of the ASAE, vol. 35, no. 3, May 1992. [Online]. Available: https://doi.org/10.13031/2013.28683
U. S. Shivhare and V. G. S. Raghavan and R. G. Bosisio, “Microwave drying of corn II. constant power, continuous operation,” Transactions of the ASAE, vol. 35, no. 3, May 1992. [Online]. Available: https://doi.org/10.13031/2013.28684
U. S. Shivhare and V. G. S. Raghavan and R. G. Bosisio, “Microwave drying of corn III. constant power, intermittent operation,” Transactions of the ASAE, vol. 35, no. 3, May 1992. [Online]. Available: https://doi.org/10.13031/2013.28685
V. Velu, A. Nagender, P. G.Prabhakara, and D. G.Rao, “Dry milling characteristics of microwave dried maize grains (Zea mays l.),” Journal of Food Engineering, vol. 74, no. 1, May 2006. [Online].Available: https://doi.org/10.1016/j.jfoodeng.2005.02.014
M. N. Berteli, E. Rodier, and A. Marsaioli, “Study of the microwave vacuum drying process for a granulated product,” Brazilian Journal of Chemical Engineering, vol. 26, no. 2, April 2009. [Online]. Available: http://dx.doi.org/10.1590/S0104-66322009000200009
A. Manickavasagan, D. S. Jayas, and N. D. G. White, “Nonuniformity of surface temperatures of grain after microwave treatment in an industrial microwave dryer,” Drying Technology, vol. 24, no. 12, December 2006. [Online]. Available: https://doi.org/10.1080/07373930601030796
R. Vadivambal, D. S. Jayas, C. Vellaichamy, and N. D. G. White, “Preliminary study of surface temperature distribution during microwave heating of cereals and oilseed,” Canadian Biosystems Engineering/Le Genie des biosystems au Canada, vol. 51, no. 3, pp. 3–45, Jan. 2009.
R. Wang, M. Zhang, and A. S. Mujumdar, “Effects of vacuum and microwave freeze drying on microstructure and quality of potato slices,” Journal of Food Engineering, vol. 101, no. 2, November 2006. [Online]. Available: https://doi.org/10.1016/j.jfoodeng.2010.05.021
L. Momenzadeh, A. Zomorodian, and D. Mowla, “Experimental and theoretical investigation of shelled corn drying in a microwaveassisted fluidized bed dryer using artificial neural network,” Food and bioproducts processing, vol. 89, no. 1, January 2011. [Online]. Available: https://doi.org/10.1016/j.fbp.2010.03.007
M. Ranjbaran and D. Zare, “Simulation of energetic- and exergetic performance of microwave-assisted fluidized bed drying of soybeans,” Energy, vol. 59, September 15 2013. [Online]. Available: https://doi.org/10.1016/j.energy.2013.06.057
(2013) Cinética de secado de maní alto oleico en microondas combinado con aire. Asociación Argentina de Ingenieros Químicos. Accessed Aug. 18, 2018. [Online]. Available: https://bit.ly/2NrttU2
P. Ghosh and N. Venkatachalapathy, “Thin layer drying of hot-air assisted microwave drying of parchment coffee,” International journal of latest trends in engineering and technology, vol. 4, no. 4, pp. 121– 133, Nov. 2014.
M. Hemis, R. Choudhary, Y. Gariépy, and V. G. S.Raghavan, “Experiments and modelling of the microwave assisted convective drying of canola seeds,” Biosystems Engineering, vol. 139, November 2015. [Online]. Available: https://doi.org/10.1016/j.biosystemseng.2015.08.010
M. Hemis, R. Choudhary, N. Becerra, P. Kohli, and V. Raghavan, “Modelling of microwave assisted hot-air drying and microstructural study of oilseeds,” International Journal of Agricultural and Biological Engineering, vol. 9, no. 6, November 2016. [Online]. Available: https://doi.org/10.3965/j.ijabe.20160906.2442
H. Jafari, D. Kalantari, and M. Azadbakht, “Semi-industrial continuous band microwave dryer for energy and exergy analyses, mathematical modeling of paddy drying and it’s qualitative study,” Energy, vol. 138, November 2017. [Online]. Available: https://doi.org/10.1016/j.energy.2017.07.111
J. Crank, The mathematics of diffusion, 2nd ed. Great Britain: Oxford University Press, 1975.
J. M. Jurado, E. C. Montoya, C. E. Oliveros, and J. Alzate, “Método para medir el contenido de humedad del café pergamino en el secado solar del café,” Cenicafé, vol. 60, no. 2, pp. 135–147, 2009.
A. D. Sharma, O. R. Kunze, and H. D. Tolley, “Rough rice drying as a two-compartment model,” Transactions of the ASAE, vol. 25, no. 1, 1982. [Online]. Available: https://doi.org/10.13031/2013.33508
N. Varadharaju, C. Karunanidhi, and R. Kailappan, “Coffee cherry drying: a two-layer model,” Drying Technology, vol. 19, no. 3-4, 2001. [Online]. Available: https://doi.org/10.1081/DRT-100103947
P. C. Corrêa, G. H. Horta, A. P. Lelis, F. Mendes, and A. L. Duarte, “Thermodynamic properties of drying process and water absorption of rice grains,” CyTA-Journal of Food, vol. 15, no. 2, 2017. [Online]. Available: https://doi.org/10.1080/19476337.2016.1238012
M. J. Muñoz, R. Correa, and M. F. Roa, “Thermal analysis of coffee hulls and their effect on the drying process in conventional ovens,” Indian Journal of Science and Technology, vol. 11, no. 36, October 2018. [Online]. Available: https://doi.org/10.17485/ijst/2018/v11i36/131682
C. Zuluaga and L. Gómez, “Dynamic modeling of coffee beans dryer,” in 2nd Colombian Conference on Automatic Control (CCAC), Manizales, Colombia, 2015.
M. M. Patiño, E. L. Pencue, and R. Vargas, “Determinación del contenido de humedad en granos de café pergamino seco utilizando speckle dinámico,” Biotecnología en el Sector Agropecuario y Agroindustrial, vol. 14, no. 2, December 2016. [Online]. Available: https://doi.org/10.18684/BSAA(14)84-91
W. Dong and et al, “Effect of microwave vac uum drying on the drying characteristics, color, microstructure, and antioxidant activity of green coffee beans,” Molecules, vol. 23, no. 5, May 2018. [Online]. Available: https://doi.org/10.3390/molecules23051146
A. Ramirez, “Internal structure and water transport in endosperm and parchment of coffee bean,” Ph.D. dissertation, Dept. Mécanique des matériaux, Univ Montpellier II - Sciences et Techniques, Languedoc, France, 2011.
How to Cite
Copyright (c) 2020 Revista Facultad de Ingeniería Universidad de Antioquia
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Revista Facultad de Ingeniería, Universidad de Antioquia is licensed under the Creative Commons Attribution BY-NC-SA 4.0 license. The material published in the journal can be distributed, copied and exhibited by third parties if the respective credits are given to the journal. No commercial benefit can be obtained and derivative works must be under the same license terms as the original work.