Two osmotic dehydration modes were applied to guava segments immersed in a 65 degrees Brix sucrose solution at 30, 40 and 50 degrees C: under constant atmospheric pressure and using a pulsed vacuum (5 min under vacuum, then at atmospheric pressure). The effective diffusivity in the liquid phase, D, and the kinetic constants of net mass transfer, K and K(0), were determined by fitting the experimental data to mathematical models. The highest effective diffusivities were obtained with pulsed vacuum at 40 and 50 degrees C on account of the hydrodynamic mechanism, with solids diffusion overcoming dehydration at the beginning of the process, at 30 and 40 degrees C. The effect of temperature on mass transfer kinetics, predictable by the Arrhenius equation, is more relevant at atmospheric pressure, where the pseudo-diffusion mechanism exerts the controlling role. (c) 2008 Elsevier Ltd. All rights reserved.