Mathematical modeling of drying kinetics for apricots:: Influence of the external resistance to mass transfer

The drying curves of halved and deseeded apricots obtained during convective drying at different temperatures (from 50 to 90 degrees C) have been examined, and a diffusional model, solved by a finite elements method, has been proposed to simulate the drying kinetics. The importance of taking into account both the internal and the external resistances to mass transfer when modeling the drying curves is discussed. Due to the geometry of halved apricots as a hemisphere losing water only through the flat section, the mass transfer coefficient (k(c)) was not correctly estimated through an empirical correlation. Only the identification of this coefficient from the experimental results allowed an accurate simulation, decreasing the mean relative error from 12.3 +/- 3.8% when k(c) was calculated through the Pasternak and Gauvin correlation to 2.9 +/- 1.0% when k(c) was identified.