Effect of microwave on the dehydration feature of apple crispy chips

The dehydration features of apple crispy chips under microwave and vacuum in combination with microwave were studied. The drying progress could be divided into constant speed phase and decreasing speed phase. The stronger the microwave power the more rapid the loss of water from the apple chips would be, and shorter the constant speed phase would become. During the whole drying progress, the loss of water mostly occurred in the decreasing speed phase. By vacuum microwave treatment, well expanded apple crispy chips with densely distributed micro-pores could be achieved. Regulating the apple chips to have a water content of 7.67% before processing by microwave drying could result in the optimal expanding effect.