Ohmic blanching of white mushroom and its pretreatment during microwave drying

Abstract

The effect of heating duration and applied voltage were investigated on heat and mass transfer of the ohmic blanching mushroom. The drying kinetics and energy consumption of blanched/control samples were studied in a microwave dryer. Results showed that the mass loss during ohmic blanching depended on heating duration and applied voltage. Variation of electrical conductivity of mushroom was calculated using basic model and validated by the first law of thermodynamics (energy balance). The electrical conductivity of mushroom, water, and mixture increased with increasing temperature. At high voltage and longer heating duration, the blanched mushrooms dried faster than un-blanched mushroom while the drying of both samples occurred in a falling rate period. Moisture diffusion for blanched samples varied in the range of 4.23–6.08 × 10−7 m2/s while it was 4.22 × 10−7 m2/s for the control sample. Blanched sample at low voltage and heating duration consumed the minimum total energy during the drying process.