A glass container containing the material to be dried was
placed inside the microwave cavity and a vacuum pump
was connected to the container for maintaining the desired
levels of vacuum inside it. Vacuum in the container was
monitored by using a vacuum gauge and a pressure regulating
valve to maintain the pressure at desirable levels. An
air tight condenser was also used in the vacuum line for
condensing the water vapour released from the samples.
About 100 g of sliced mushrooms were taken for each drying
experiments in the microwave-vacuum dryer at different
microwave power and pressure levels. The sample
remained in the container for a specified time interval
while drying took place. The weight of the sample was
recorded at every 5 min intervals by switching off the
microwave oven and after releasing the vacuum, which
took about 40 s for each observation. The samples were
dried till the moisture content was reduced to 6–6.5%