assumes that the energy absorption was solely
due to the microwave energy, and there was no heat gain
or loss to the surroundings, furthermore,cp of water did
not change with temperature.
The standard procedure described by Schiffmann
(1987) was used to determine the power output.
Deionised water weighing 1000 g and equilibrating at
temperature of 5 C below room temperature, was heated in the microwave–vacuum dryer at full power, 80%
full power and 50% full power, respectively. Heating was
continued for a period of time until the final temperature of the water load reached 5 C above room temperature (18C). The water temperatures before and
after heating were measured using ak-type thermocouple probe after the water was thoroughly stirred for
uniform temperature. Three replicates were performed
for each measurement, and the mean value and standard
deviation of power output was reported. In the current
study, the power output for full power, 80% full power
and 50% full power were 336.5 ± 1.7, 267.5 ± 2.1 and
162.8 ± 2.3 W, respectively.