Comparative study of natural solar drying of cassava, banana and mango

This paper is about a comparative study of some parameters related to natural solar drying of cassava, ripe(I) or raw(II) plantain banana and mango. The comparative study was carried out by investigating the constant rate period, the falling rate period and the transition between these two periods. For the constant rate period, the product temperature T-p and the ambient temperature T-a were analysed in relation with the initial moisture content W-i. Then the maximum temperature difference DTmax between T-a and T-p was investigated, and found to decrease exponentially with W-i. In the constant rate period, parameters such as h(c)/lambda, dm/dt and the mass transfer coefficient h(m) were reported and discussed. A new parameter was then introduced and termed the specific rate R-sp, which strongly correlated to Wi and DTmax. The critical point W-c was also taken into account. As for the falling rate period, the study was carried out by means of the overall resistance to diffusion R-ds. The next step was the analysis of the drying rhythms. Finally, the investigation about the rewetting behaviour of the four products was made by using the desorption and sorption velocities (V-des and V-sor), and the rewetting rate, too. (C) 2003 Published by Elsevier Ltd.