Combination of closed loop-fluidized bed dryer and osmotic drying for processing of white mushroom: mass transfer, drying kinetics and specific moisture extraction rate

ABSTRACT

The effect of combined osmotic drying and closed-fluidized bed drying on mass transfer coefficients, drying kinetics and specific moisture extraction rate of mushroom slices was investigated. Four thin-layer drying models available in the literature were fitted to the experimental data. The osmotic pretreatment reduced about 5.4–48.7% of fluidized bed drying time than the control state. Effective moisture diffusivity ranged from 0.83 × 10⁻¹⁰ to 2.43 × 10⁻¹⁰ m²/s and 1.35 × 10⁻¹⁰ to 4.21 × 10⁻¹⁰ m²/s for control and osmotic pretreatment samples, respectively. Activation energy decreased using pretreatment process. Maximum specific moisture extraction ratio is obtained at low air velocity and drying temperature with osmotic pretreatment. The Page model gave the best predictions for the drying characteristics of mushroom slices for all treatments.

KEYWORDS:

• Osmotic
• mushroom
• closed dryer
• fluidized bed
• modeling