in drying time occurred with the increasing drying time in the
hot air cabinet dryer from 30 to 120 min at any microwave
power level. The drying rate curves indicated the absence of
a constant-rate drying period. After reaching its maximum value
the drying rate initially dropped rapidly, signifying a falling-
rate period. The drying behavior when the grapes dried
by starting drying in hot air cabinet dryer for 30 min and finishing
by microwave oven for 1 min at different power levels
were not different. Within a certain microwave power level
range (75–900 W in this study), increasing microwave power
speeds up the drying process, thus shortening the drying time.
Also, when grapes drying started in hot air cabinet dryer,
increasing drying time from 30 to 120 min until the moisture
ratio was near to 0.02, the drying time increased.
For microwave oven followed by hot air cabinet drying
method, moisture ratio-time diagram of grapes along the drying
period when grapes dried by starting drying in microwave