Evaluation of the shrinkage effect on the modeling kinetics of osmotic dehydration of sweet potato (Ipomoea batatas (L.)

Abstract

The kinetics of water loss (WL), solid gain (SG) and water activity (aw) of the osmotic dehydration of sweet potato (Ipomoea batatas (L.)) slices were investigated. Three osmotic solutions, sucrose, sorbitol and fructose, were used with two different water activities, 0.900 and 0.940. The diffusivities of both water and solute were evaluated by using Crank's analytical solution to Fick's second law and according to the models of Azuara and Barbosa Júnior et al. The shrinkage effect was considered to estimate the water and solid diffusion. A lower aw of the osmotic solutions resulted in higher mass transfer parameters (WL and SG) and a lower aw of the product. Sorbitol promoted higher WL and sorbitol and fructose, higher SG. The shrinkage was directly proportional to moisture reduction. Among the tested mathematical models, the Barbosa Júnior et al. presented the best fit. The shrinkage resulted in lower water and solid diffusivity values.