This research concerns a process development study focussing the application of microwaves to pulped coffee cherries production, in order to reduce the drying time and increase the industrial yield and product quality when compared to conventional drying processes. Two drying cycles were tested: a) a hot air drying process using a conventional batch rotary dryer from 45-50 to 11-13% w.b. product moisture; b) a two stage process, whereby the product was pre dried with hot air from 45-50 to 30% w.b., followed by a final microwave and hot air drying stage, to reduce product moisture from 30 to 11-13% w.b. The overall drying time was reduced from 15 to 37.5 hours to about 10 hours, respectively. The sensory quality of the product was evaluated by the "cup test", complemented by electronic microscope scanning analyses (EMS) and showed satisfactory results. A preliminary study of the economic aspects involved in up-grading an industrial scale coffee processing line with a microwave system was also outlined.
microwave; drying; pulped coffee cherry beans
