Description of the osmotic dehydration and convective drying of coconut (Cocos nucifera L.) pieces: A three-dimensional approach

Osmotic dehydration is a cheap alternative in the partial removal of water during the production of dried fruits. Generally, the production process is completed with conventional drying, and both the removal methods can be described by diffusion. This article presents a detailed three-dimensional description of the water removal from semi-mature coconut slices parallelepiped-shaped, using a diffusion model. Coconut pieces were submitted to osmotic dehydration, using a solution of sucrose and water in a concentration of 35° Brix, at temperature of 40 °C, followed by convective drying at 50, 60 and 70 °C. The analytical solution of the three-dimensional diffusion equation was coupled to an optimizer, and the process parameters were determined using the obtained experimental data. The analysis of the results makes it possible to conclude that the model with boundary condition of the third kind satisfactorily describes the diffusion processes.

► Osmotic dehydration is a cheap alternative in the partial removal of water. ► A detailed description of the process in semi-mature coconut slices is presented. ► To this end, diffusion equation and optimization algorithm is used. ► A model with boundary condition of the third kind well describes the process.