| Abstrakt: |
Osmotic dehydration of yacon ( Smallanthus sonchifolius) was carried out in varying temperatures (30 and 50 °C) and glycerol or sorbitol concentration (30, 50, and 70 %). The solution of Fick's law for unsteady state mass transfer in a plane sheet configuration was used to calculate the effective diffusivities of water. Peleg's model was used to predict the equilibrium condition, which was shown to be appropriate for water loss and solute uptake. It was found to have two rate periods of dehydration. For the above conditions of osmotic dehydration, the effective diffusivity of water was found to be in the range of 5.82 ± 0.68 × 10 to 2.15 ± 0.61 × 10 m/s in first period and 1.60 ± 0.28 × 10 to 1.29 ± 0.24 × 10 m/s in second period for glycerol tests and, for sorbitol, was 3.82 ± 0.17 × 10 to 1.54 ± 0.50 × 10 m/s for the first period and 1.73 ± 0.04 × 10 to 1.33 ± 0.06 × 10 m/s for the second. The greatest reduction in water activity was achieved when 70 % of glycerol was used at 50 °C (final a 0.704 ± 0.010). The treatments with 70 % of solution concentration at 30 °C were repeated, and by adding 20 g/L of calcium lactate in the osmotic solution, it resulted in higher calcium content, strengthening the cell wall for both solutes. Microstructure of the yacon samples (fresh, blanched, and in different conditions of osmotic dehydration) was examined by scanning electron microscopy. [ABSTRACT FROM AUTHOR] |
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