Cocoa Beans Microwave Pulse Drying: Characterization of the Moisture Transfer


  • Arsène Nogbou
  • Kisselmina Kone
  • Djedjro Akmel
  • Emmanuel Assidjo



Drying, Microwave, Mass transfer, Cocoa


The aim of this study was to characterize the moisture transfer during microwave pulse drying of cocoa beans. Experiments were carried out on fermented cocoa beans using a domestic microwave oven. Three microwave power levels (450 W, 600 W and 700 W) were used. The moisture transfer characterization was made using the estimation of mass transfer parameters and a modeling. The estimated mass transfer parameters were the Biot number (Bi), the diffusivity (D) and the mass transfer coefficient (km). They were given by the analytical method of Dincer. The 2nd Fick’s law was used for the moisture transfer modelling. The results obtained showed that for the whole microwave powers, the Bi values were included between 0.57 and 0.62. The D values, for the various microwaves powers (450 W, 600 W and 700 W), were respectively 6.01×10-9 m².s-1, 10.27 ×10-9 m².s-1and 11.94×10-9 m².s-1. The km values varied between 9.87×10-7 m.s-1and 21.33×10-7 m.s-1. The Fick’s model application showed a good adequacy between the experimental values and those simulated. R² of the Fick’s model for the whole microwave power levels, was higher than 0.998.


- Barel, M. Qualité du cacao : l’impact du traitement post-récolte, Savoir-faire, Editeur Quae, Paris, pp. 3-78, 2013.

- Hii, C., Law, C. & Law, M. Simulation of heat and mass transfer of cocoa beans under stepwise drying conditions in a heat pump dryer. Applied Thermal Engineering, 54 (1), pp. 264–271, 2013.

- Beaudry, C., Raghavan, G.S.V. & Rennie, T.J. Microwave finish drying of osmotically dehydrated cranberries. Drying Technology, 21, pp. 1797-1810, 2003.

- Soysal, Y., Oztekin, S. & Eren, O. Microwave Drying of Parsley: Modelling, Kinetics, and Energy Aspects. Biosystems Engineering, 93(4), pp. 403-413, 2006.

- Sorour, H. & EL-Mesery H. Effect of microwave and infrared radiation on drying of onion slices. Impact Journals, 2(5), pp. 119–130, 2014

- Hebbar, H. U. & Rastogi, N. K. Microwave Heating of Fluid Foods. Novel Thermal and Non-Thermal Technologies for Fluid Foods, pp. 369–409, 2012.

- Chandrasekaran, S., Ramanathan, S. & Basak, T. Microwave food processing — A review. Food Research International, 52(1), pp. 243–261, 2013.

-Kermasha, S., Bisakowski, B., Ramaswamy, H., & Van de Voort, F. Comparison of microwave, conventional and combination heat treatments on wheat germ lipase activity. International Journal of food Science and Technology, 28, pp. 617–623, 1993.

-George, J. P. & Datta, A. K. Development and validation of heat and mass transfer models for freeze-drying of vegetable slices. Journal of Food Engineering, 52(1), pp. 89–93, 2002.

-Srikiatden, J. & Roberts, J. S. Moisture Transfer in Solid Food Materials : A Review of Mechanisms, Models, and Measurements. International Journal of Food Properties, 10, pp. 739–777, 2007.

-Zogzas, N. P., Maroulis, Z. B. & Marinos-Kouris, D. Moisture diffusivity - Methods of experimental determination - A review, Drying Technology, 12(3), pp. 483-515, 1994.

-Mcminn, W. A. M., Khraisheh, M. A. M., & Magee, T. R. A. (2003). Modelling the mass transfer during convective , microwave and combined microwave-convective drying of solid slabs and cylinders. Food Research International, 36, pp. 977–983, 2003.

-Dincer, I. & Dost, S. A modelling study for moisture diffusivities and moisture transfer coefficients in drying of solid objects. International Journal of Energy Research, 20, pp. 531–539, 1996.

-Wiberg, P. & Moren, T. J. Moisture flux determination in wood during drying above fiber saturation point using CT-scanning and digital image processing. Holz als Roh und Werkstoff, 57(2), pp. 137-144, 1999.

- Gunasekaran, S. Pulsed microwave–vacuum drying of food materials. Drying Technology, 17, 95-412, 1999.

- Darvishi, H., Azadbakht, M., Rezaeiasl, A. & Farhang, A. Drying characteristics of sardine fish dried with microwave heating. Journal of the Saudi Society of Agricultural Sciences, 12, pp. 121-127, 2013.

- Akmel, D. C., Assidjo, E. N., Kouamé, P. & Yao, K. B. Mathematical Modelling of Sun Drying Kinetics of Thin Layer Cocoa (Theobroma Cacao) Beans. Journal of Applied Sciences Research, 5(9), pp. 1110–1116, 2009.

- Dadali, G., Demirhan, E. & Ozbek, B. Microwave Heat Treatment of Spinach: Drying Kinetics and Effective Moisture Diffusivity. Drying Technology, 25, pp. 1703-1712, 2007.

-Bal, L., Kar, A., Satya, S. & Naik, S., Drying kinetics and effective moisture diffusivity of bamboo shoot slices undergoing microwave drying. International Journal of food Science and Technology, 45, pp. 2321–2328, 2010.

- Su, D., Zhang, M., Wei, Z., Tang, X., Zhang, R., Liu, L., Deng, Y. Effect of microwave power on kinetics and characteristics of microwave vacuum-dried longan (Dimocarpus longan Lour.) pulp. Food science and Technology International, 21 (2), pp. 124 –132, 2015.

- Koné, K. Amélioration de la qualité de la tomate séchée par microonde assistés par air chaud avec pilotage de la puissance spécifique. Thèse. Ecole doctorale ABIES, AgroParitech, pp. 8- 223, 2011.

- Sharma, G. P. & Prasad, S. Drying of garlic (Allium sativum) cloves by microwave - hot air combination. Journal of Food Engineering, 50, pp. 99–105, 2001.

- Wang, Z., Sun, J., Chen, F., Liao, X. & Hu, X. Mathematical modelling on thin layer microwave drying of apple pomace with and without hot air pre-drying. Journal of Food Engineering. 80, pp. 536–544, 2007.

-Therdthai, N. & Zhou, W. Characterization of microwave vacuum drying and hot air drying of mint leaves (Mentha cordifolia Opizex Fresen). Journal of Food Engineering, 91, pp. 482–489, 2009.

-Dincer, I. Moisture loss from wood products during drying. Part I. Moisture diffusivities and moisture transfer coefficients. Energy Sources, 20 (1), pp. 67–75, 1998.

- McMinn, W.A.M., Khraisheh, M.A.M. & Magee, T.R.A. Modelling the mass transfer during convective, microwave and combined microwave-convective drying of solid slabs and cylinders. Food Research International, (36), pp. 977-983, 2003.

-Sadeghi, M., Kesbi, O. M. & Mireei, S. A. Mass transfer characteristics during convective, microwave and combined microwave – convective drying of lemon slices. Journal of the Science of Food and Agriculture, 93, pp. 471–478, 2013.

-Mcminn, W. A. M. Prediction of moisture transfer parameters for microwave drying of lactose powder using Bi – G drying correlation. Food Research International, 37, pp. 1041–1047, 2004.

- Mrkic, V., Ukrainczyk, M. & Tripalo, B. Applicability of moisture transfer Bi – Di correlation for convective drying of broccoli. Journal of Food Engineering, 79, pp. 640–646, 2007.

- Dincer, I. & Hussain, M. M. Development of a new Biot number and lag factor correlation for drying applications. Journal of Heat and Mass Transfer, 47, pp. 653–658, 2004.

-Akpinar, E. K. & Dincer, I. Moisture transfer models for slabs drying. International communications in Heat and Mass Transfer, 32, pp. 80–93, 2005.

- Panagiotou, N. M., Krokida, M. K., Maroulis, Z. B. & Saravacos, G. D. Moisture Diffusivity: Literature Data Compilation for Foodstuffs. International Journal of Food Properties Moisture Diffusivity, 7 (2), pp. 273-299, 2004.

- Sutar, P. & Prasad, S. Modeling microwave vacuum drying kinetics and moisture diffusivity of carrot slices. Drying Technology, 25, pp. 1695–1702, 2007.

- Páramo, D., García-alamilla, P., Salgado-cervantes, M., Robles-olvera, V. & Rodríguez-Jimenes G. Mass transfer of water and volatile fatty acids in cocoa beans during drying. Journal of Food Engineering, 99(3), pp. 276–283, 2010.

- Garcia-Alamilla, P., Salgado-cervantes, M., Barel, M., Berthomieu, G., Rodriguez-Jimenez, G. & Garcia-Alvarado, M. Moisture, acidity and temperature evolution during cacao drying. Journal of Food Engineering, 79, pp. 1159–1165, 2007.

- Daud, W., Talib, M. & Kyi, M. Drying with Chemical Reaction in Cocoa Beans. Drying Technology, 25, pp. 867–875, 2007.

-Dadali, G. & Ozbek, B. Microwave heat treatment of leek : drying kinetic and effective moisture diffusivity. International Journal of Food Science & Technology, 43, pp. 1443–1451, 2008.




How to Cite

Nogbou, A. ., Kone, K., Akmel, D., & Assidjo, E. (2016). Cocoa Beans Microwave Pulse Drying: Characterization of the Moisture Transfer. Asian Journal of Agriculture and Food Sciences, 4(6).