Microwave Drying of Osmotically Dehydrated Blueberries

Abstract

The drying rates, rehydration ratios, color, texture and sensory evaluations of blueberries that were pretreated with ethyl oleate and sodium hydroxide, osmotically dehydrated in sucrose and dried in various regimes were compared. The drying regimes were: convection (35 °C or 45 °C at 2 m s-1); microwave-assisted convection (0.1 or 0.2 W g-1 incident power and freeze-drying. Convection and microwave-assisted convection trials were performed in a 750 W multimode cavity microwave drier equipped with electrical heaters and blower. The berries were dried to 15% moisture content (wet basis). Jr was concluded that the procedure involving pretreatment, osmotic dehydration and microwave-assisted drying led to a dried blueberry that was comparable to the freeze-dried berry in a much shorter time. Convection drying took the longest time.