Mass Transfer Properties for the Drying of Pears

Portugal is among the tropical countries that have a long tradition of drying fruits, such as figs, grapes or pears. The knowledge of the transfer phenomena involved in drying processes is of major importance for the design and optimization of the most adequate operating conditions. In this way, the present work intended to study the mass transfer properties for the convective air drying of pears, based on the diffusion model. The values of the diffusivity and mass transfer coefficient for the drying of pears of the Portuguese native variety D. Joaquina were determined for two drying temperatures, 60 ºC and 70 ºC. The results obtained showed an increase of 38 % in diffusivity and an even more pronounced increase in the mass transfer coefficient, 56 %, for a temperature variation of 10 ºC. Regarding the dimensionless numbers, Biot number increased 13 % while Dincer number decreased 28 %