Mathematical modelling of sun drying kinetics of thin layer cocoa (Theobroma cacao) beans.

Abstract

In this work, t he sun drying behaviour o f co coa beans w as inv estigated. Drying experiments were conducted for organic fermented cocoa beans grown in Yamoussoukro, Ivory Coast. The experimental drying curves obtained show o nly a f alling rat e period. I n ord er t o estimate and select the suitable fo rm air drying curves, the drying data were fitted to fourteen d ifferent mathematical models. Coefficient of determination ( R²) and ot her statistical parameters, such as reduced chi -square ( x²), root mean square error (RMSE), mean bias error (MBE) and Student t statistic were used for determination of the best suitable mod el. Among the mathematical models investigated, the logarithmic mod el satisfactorily described the drying behaviour o f co coa beans w ith highest R ² a nd lowest x², RMSE and MBE. The ap parent diffusion co efficient, varying from 3.70x10 to 5.80x10 m²/s, is an i mportant - 11 - 11 parameter i n t he m oisture transfer, and they were found to be dependent on the t emperature, relative humidity and velocity of t he drying air. The activation energy w as e stimated to 22.48 KJ/mol.