Effect of thermosonic pretreatment on drying kinetics and energy consumption of microwave vacuum dried Agaricus bisporus slices

This study was conducted to evaluate the drying kinetics and energy consumption of microwave vacuum dried Agaricus bisporus slices using various thermosonic pretreatment procedures. All the considered thermosonic pretreatment procedures involved complete inactivation of the PPO in A. bisporus slices. It was found that thermosonic pretreatment removed approximately 40%-45% of water in A. bisporus slices. The experimental data of the followed microwave vacuum drying process was fitted and Page model showed excellent for explaining the drying characteristics of microwave vacuum dried A. bisporus slices both untreated and thermosonically treated. A simplified and modified form of Fick's second law was primarily used to calculate the moisture diffusivity during microwave vacuum drying, which was observed to vary between 3.68 x 10(-8) and 1.52 x 10(-7) m(2)/s, with the activation energy varying between 41.87 and 49.52 kJ/mol. In addition, the input energy and specific energy requirements for drying of the thermosonically pretreated A. bisporus samples were respectively determined to be within 0.30-0.54 kWh and 4.97-9.97 kWh/kg for power supplies ranging between 481 and 865 W and a constant vacuum degree of 70 kPa. Thermosonic pretreatment not only improved the product color of the microwave-vacuum-dried A. bisporus slices, but also reduced the energy consumption of the drying process. (C) 2015 Elsevier Ltd. All rights reserved.