Hybrid drying of pulped arabica coffee cherry beans (Coffea arabica L. cv. Catuai) using a hexagonal microwave dryer designed by numerical simulations

Abstract

The consumption of specialty coffees has been increasing significantly in recent years. Their quality is influenced by several factors and the drying method is the most important. In order to reduce drying time and maintain the quality of the coffee, several techniques have been used, among which the microwave-assisted convective drying stands out. In this work, a hexagonal microwave dryer was developed using numerical simulation techniques; then some parameters were evaluated in drying of special coffee using air at room temperature and microwaves heating, named hybrid drying. The results showed that the simulations reaches good results, being possible its use in the prediction of the electromagnetic fields and dimensioning of hexagonal cavities. In addition, the prototype performed well in the coffee drying, influenced by the coffee mass, temperature and time, reducing the moisture content from 50.4 to 10 g/100 g wet basis in 5 hr. The hybrid drying was advantageous compared with convective or microwave drying processes.