Microwave-Assisted Drying Equipment

Microwave-Assisted Drying Equipment 1289 r Magnetron generator... 

To date, only microwave hot-air dryers used principally in flnish drying processes to level-off the moisture content in pasta, crackers or chips, and microwave vacuum dryers custom-made to specific product requirements, are available commercially (Ratti, 2008). Good microwave-assisted drying equipment should have a uniform distribution of the microwave field, provide a movement of the material to be dried, keep the microwave field strength in the drying chamber lower than the dielectric breakdovm strength, and possess an economic dehumidification system. 

Before applications are dealt with, the main variables governing microwave-assisted processes and the parameters characterizing specific microwave treatments are examined. The applications discussed include not only microwave-assisted digestion and extraction — which are the two most widely implemented and hence those with the highest potential interest to readers — but also others of special significance to solid sample treatment such as microwave-assisted drying, distillation and protein hydrolysis. Finally, some safety recommendations on the use of microwave equipment are made. 

Chapter 9 Microwave-assisted drying of foods - Equipment, process and product... 

Microwave-Assisted Drying of Foods - Equipment, Process and Product Quality... 

Fig. 9.9 Laboratory-scale microwave-assisted freeze-drying equipment. 1, MWFD chamber 2, Fiber-optical temperature sensor 3, Vacuum breakage valve, for MWFD 4, Sample supporting plate ...

A typical schematic diagram of microwave-assisted freeze-drying equipment is shown in Fig. 9.9. During drying, the pressure was maintained at 100 Pa by a vacuum pump, and the temperature of the cold trap (—40 to —45 °C) was sufficiently low to condense the vapor. The microwave frequency was 2450 MHz and the power could be regulated continually from 0 to 2000 W. 

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