A multifunctional and programmable MWV dryer, with a maximum
nominal power of 4.2 kW, and an operation frequency of
2450 MHz was used in this research. We designed this dryer and
had it manufactured by Guangzhou Kailing Industrial Microwave
Equipment Ltd. (Guangzhou, Guangdong, China) (Song, Zheng, &
Zeng, 2009). The operational power is adjustable between 0W
and 4000 W. The dimensions of the microwave cavity were
500 500 500 mm. The maximum vacuum degree is 95 kPa
(Tian et al., 2012). Samples were placed in thin layers on six plates;
these were then placed in the microwave cavity and rotated at
1 rpm during microwaving of the material. The equipment was
operated for 11 min at a microwave power density of 15 W/g and
vacuum degree of 80 kPa. The drying process continued until
the moisture content of shiitake mushrooms reached a dimensionless
moisture ratio of 13% on wet basis.