Microwave Finish Drying of Diced Apples in a Spouted Bed

TLDR

The study evaluated combining a spouted bed with microwave heating to enhance heating uniformity during apple drying. Laboratory experiments dried 24 % moisture diced apples to 5 % at 70 °C air using four microwave power densities (0–6.1 W g⁻¹). The combined method achieved markedly better temperature uniformity, reduced discoloration, higher rehydration rates, and cut drying time by over 80 % versus conventional hot‑air or spouted‑bed drying.

Abstract

ABSTRACT The combination of a spouted bed with microwave heating to improve heating uniformity was evaluated. Experiments were performed on a laboratory system in which evaporated diced apples of about 24% moisture were dried to about 5% at 70°C air temperature using four levels of microwave power density (0 to 6.1 W/g). With the combination method, temperature uniformity in diced apples was greatly improved as compared to that with a stationary bed during microwave drying. Products had less discoloration and higher rehydration rates as compared to conventional hot air drying or spouted bed (SB) drying. Drying time could be reduced by >80% compared with SB drying without microwave heating.