Evaluation of quality properties and water mobility in vacuum microwave-dried carrot slices using pulse-spouted bed with hot air

Fried carrot slices feature high fat content to impair people healthy. To resolve this issue, microwave hot air-assisted pulse-spouted vacuum drying (MHAPSVD) has been designed using microwave vacuum dry on pulse-spouted bed with hot-air steam. Dying characteristics, moisture mobility and qualities of carrot slices had been confirmed after dying using 915 MHz microwave generator. Experiment was carried out at 3 W/g, 90 degrees C air stream, 0.08 MPa vacuum pressure and 2 s pulse interval for drying time of 10-80 min. The quality properties of color, odor, rehydration ratios, shrinkage ratios as well as tastes in 70 min drying are found to be suitable for a snack food. High moisture stability of carrot slices was achieved after 50 min. Free water decreased dramatically from start to 20 min and bound water declined sharply from 20 to 50 min. MHAPSVD could be a high efficient and quality drying technology for crisp product.