Figs. 3–5 further show the effect of changing the process
variables, namely microwave power, system pressure and
sample thickness on drying time during microwave-vacuum
drying. It is evident that the drying time decreases with the
increase in power output. When microwave power level
and product thickness remain constant, the drying rate at
higher vacuum level was slightly greater. However, the
effect of system pressure on drying time was not as significant
as that of microwave power. Concerning the effect of
the sample size on drying time, mushroom slices of smaller