A Comparative Study on Drying and Coating of Osmotic Treated Apple Rings




In this study, the effect of edible coat (carboxy methyl cellulose) before osmotic dehydration and
different drying methods on sensory and physical properties of dried apple (V. Golden delicious)
rings was investigated. The coated and non-coated samples pretreated with 50% sucrose osmotic
solution and dried in freeze drier (-40 to -50°C, 0.026-0.017 mbar, 24 hr), vacuum drier (70°C, 200
mbar, 8-10 hr), air dryer (60°C, 1.5 m/s, 2-3 hr). Sensory evolutions, Rehydration ratio (RR), color
changes (ΔE), shear strength (SS), true density and shrinkage present of dried samples were
determined. Effect of using edible coats before osmotic process was significant on the SS, RR and
color changes. As the lowest shrinkage, color changes, RR, and highest SS were found in freeze
dried apples. The air and vacuum dried samples had the highest RR and true density, respectively.
The best sample in sensory evolutions was coated and freeze dried samples.