Dehydration of aloe vera: simulation of drying curves and evaluation of functional properties

The effect of air-drying temperature (from 30 degrees C to 80 degrees C) on dehydration curves and functional properties (water retention capacity, WR C; swelling, SW; fat adsorption capacity, FAC) of aloe vera cubes has been investigated. A diffusional model taking into account sample shrinkage has been proposed and solved by using a finite difference method. The effective diffusivities estimated with the proposed model varied with the air-drying temperature according to the Arrhenius law except for the experiment carri ed out at 80 degrees C, where case-hardening took place. Simulation of aloe vera drying curves by using the model was accurate (percentage of explaine d variance (%var): 99.7 +/- 0.1%). Furthermore, drying kinetics of aloe ver a cubes of different sizes to those used to develop the model could be sati sfactorily predicted (%var: 99.5 +/- 0.2%). The three studied functional pr operties exhibited a maximum when drying temperature was 40 degrees C decre asing either at higher or lower temperatures. (C) 2000 Elsevier Science Ltd . All rights reserved.