DEVELOPMENT AND EVALUATION OF DRUM COFFEE ROASTING MACHINE FOR SMALL-SCALE ENTERPRISES

The design, manufacture and evaluation of a drum coffee roasting machine had been carried out. The aimed of the study was to develop a small-scale drum roaster to meet the demand of the small enterprises at design and function. The development stage consisted of sizing of the main components, creating technical drawings, determination of component materials, manufacture and performance test. The dimension of the roaster drum was 168.28 mm in diameter and 250 mm in length; the capacity of the roaster was 750 gram/batch. Results of the test determined that the coffee roasting machine had worked well as expected. The preheating time was 15-22 minutes at a drum speed of 67.5 rpm. The initial loading temperature was 180°C. The test using arabica coffee bean reveals that the average crack time was 8.78 minutes, development time was 2.35 minutes, decreasing mass and increasing volume ranged from 19.80 – 20.30 % and 49.97 – 54.85 % respectively. The average crack time of Robusta coffee bean was 10 minutes; development time was 3 minutes, decreasing mass and increasing volume ranged from 10.87 – 14.90 % and 44.93 – 56.20 %, respectively. The required time to roast Arabica green coffee bean to the light-medium and medium-dark level was 11.3 and 12.38 minutes respectively, besides for Robusta green coffee beans was 13.00 and 14.00 minutes respectively.