Cocoa Bean (Theobroma cacao L.) Drying Kinetics.

Ndukwu MacManus Chinenye1*, A.S. Ogunlowo2, and O.J. Olukunle2

Cocoa (Theobroma cacao L.) is widely produced in West Africa and South America and is a great economic tree crop, with so many industrial uses. In this work, the experimental drying kinetics of foreign species was investigated, and the experiments were carried out under isothermal conditions, using heated batch drier at 55, 70 and 81 ºC. The moisture ratio data obtained from change of moisture content with the drying time was fit to two thin layer drying model with good results. A faster drying process was observed at a higher drying temperature resulting in higher drying rates which is advantageous when evaluating costs. Fick’s second law of diffusion was used to predict effective diffusivity using experimental data assuming that the variation of diffusivity with temperature can be expressed by an Arrhenius type function, and the values of diffusivity obtained ranged from 6.137 x 10-10 to 2.1855 x 10-9 m2 s-1 for the temperature used. The Arrhenius constant (D) is predicted at 8.64 x 10-4 m2 s-1 while the activation energy was predicted at 39.94 kJ mol-1.

Keywords: moisture content, drying temperature, diffusivity, moisture ratio, equilibrium moisture content.
1Michael Okpara University of Agriculture, Department of Agricultural Engineering, Umudike P.M.B. 7267, Umuahia Abia State, Nigeria. *Corresponding author (ndukwumcb@yahoo.com).
2Federal University of Technology Akure, Department of Agricultural Engineering, P.M.B. 704 Akure, Ondo State, Nigeria.