The rate of water loss during osmotic dehydration of sweet potato was directly related to solution concentration. An antagonistic effect between the two solutes (sucrose and NaCl) was observed where the positive salt-sucrose interaction effect on soluble solids determined a decrease of solid gain when NaCl and sucrose were at maximum concentrations (50% sucrose/10% NaCl).
The experimental values of water loss and solid gain during the osmotic dehydration of sweet potato slices were fitted to Peleg, Fick and Page’s equations. Peleg’s equation presented the best adjustment of the experimental data.
Peleg’s parameters 1/k1 and 1/k2 for water loss were from 0.09 to 0.30 and from 3.13 to 5.56, respectively, and for solid gain they varied from 0.01 to 0.18 and 0.67 to 1.67, respectively. Page’s parameters A and B for water loss were from 0.07 to 0.17 and from 0.53 to 0.62, respectively, and for solid gain they ranged from 0.02 to 0.41 and 0.36 to 0.73, respectively.
The effective diffusion coefficients obtained from Fick’s equation ranged from 3.82 x 10–10 to 7.46 x 10–10 m2/s for water loss and from 1.18 x 10–9 to 3.38 x 10–10 m2/s for solid gain.