Microwave-vacuum drying characteristics of carrot (daucus carota L.)

Abstract

Sliced carrots were dried in a constant-power microwave oven by applying microwave power in pulsed and continuous manner while subjecting the samples to different vacuum levels. The drying kinetics as well as dried product quality, such as color and rehydration ability, were determined. Experimental moisture loss data versus drying time data were fitted to nine thin-layer drying models. The Page model fit the best in describing drying kinetics when samples were dried in 10.67 kPa vacuum with pulsed application of 500 W microwave power; for all other drying conditions, the Midilli model fit was better. Carrot samples dried in the pulsed mode had higher color values (L-*, a(*) and b(*)) than those dried in the continuous mode. The samples dried at 500 W continuous mode in 5.33 kPa vacuum exhibited higher rehydration ratios than the other dried samples.