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

Subject Areas : International Journal of Agricultural Science and Research

P. Farzaneh ¹ , H. Fatemian ² , E. Hosseini ³ , Gh. H. Asadi ⁴ , F. Darvish ⁵

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Received: 2011-07-24 Accepted : 2011-10-17 Published : 2012-06-08

Keywords: Freeze drying, Vacuum drying, Air drying, Coating, Osmotic pretreatment, Physical properties,

Abstract :

In this study, the effect of edible coat (carboxy methyl cellulose) before osmotic dehydration anddifferent 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 osmoticsolution and dried in freeze drier (-40 to -50°C, 0.026-0.017 mbar, 24 hr), vacuum drier (70°C, 200mbar, 8-10 hr), air dryer (60°C, 1.5 m/s, 2-3 hr). Sensory evolutions, Rehydration ratio (RR), colorchanges (ΔE), shear strength (SS), true density and shrinkage present of dried samples weredetermined. Effect of using edible coats before osmotic process was significant on the SS, RR andcolor changes. As the lowest shrinkage, color changes, RR, and highest SS were found in freezedried 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.