Assessment of Osmotic Process in Combination with Coating on Effective Diffusivities during Drying of Apple Slices

Abstract

The effect of carboxymethyl cellulose (CMC) coating on the mass exchanges during the osmotic dehydration of apples and its effect on the quality of final product were studied. Coating semi-rings of apple with CMC solution (1%) was found to prevent solute uptake and to reduce salt diffusion coefficient from 4.35 × 10⁻¹⁰ m²/s to 2.86 × 10⁻¹⁰ m²/s. However, coating did not significantly affect the diffusivity of water. The effective diffusivity of salt and consequently solids gain were found to be depended on the concentration of CMC solution in the range of 0–1%. Increasing the concentration of CMC further from 1% had no effect on the mass exchanges during the osmotic process. Maximum performance ratio, defined as water loss/solids gain, and the lowest solids diffusion was observed for coated samples (with 1% CMC solution) treated with an osmotic solution containing glucose syrup (50%) and NaCl (2%).

Keywords:

• Carboxymethyl cellulose
• Coating
• Effective diffusivity
• Mass transfer
• Osmotic dehydration

Notes

Mean values followed by the same superscript within the same column are not significantly different (p ≤ 0.05).

Mean values followed by the same superscript within the same column are not significantly different (p ≤ 0.05).