Microwave-assisted air dehydration of apple and mushroom

Abstract

Microwave-assisted hot-air dehydration of apple and mushroom was performed with low-power microwave energy. The purpose of the investigation was to compare hot-air drying and microwave-assisted hot-air drying. The air velocity, the microwave output power and the air temperature were the variables in the experiments. The microwave energy was supplied by either microwave applicators with transverse magnetic (TM) modes as dominant modes, or by a multimode cavity microwave oven. The quality parameters were rehydration capacity, bulk density, and colour. Low air velocity caused a browning of the products and a minimum air velocity of 1 m/s was identified. It was possible to reduce the drying time by a factor of two for apple and a factor of four for mushroom by using microwave-assisted hot-air drying. Rehydration capacity was 20–25% better for TM applicator-dried apples and mushrooms than for multimode cavity dried ones.