Kowshik Kumar Saha
Scientific Officer
Farm Machinery and Postharvest Process Engineering Division,
Bangladesh Agricultural Research Institute,
Gazipur-1701.
M Ayub Hossain
Principle Scientific Officer
Farm Machinery and Postharvest Process Engineering Division,
Bangladesh Agricultural Research Institute,
Gazipur-1701.
M Arshadul Hoque
Senior Scientific Officer
Farm Machinery and Postharvest Process Engineering Division,
Bangladesh Agricultural Research Institute,
Gazipur-1701.
M Mohabbat Ullah
Principle Scientific Officer
Hill Agricultural Research Station,
Bangladesh Agricultural Research Institute,
Khagrachari.
Roasting of coffee beans is a thermal process. The aroma and flavor of coffee are developed during roasting. A power operated horizontal drum type coffee roaster was developed at Farm Machinery and Postharvest Process Engineering Division of Bangladesh Agricultural Research Institute during 2011-2012. The roaster was made of locally available materials. An LP gas fired burner was used as the heat source and an electric motor of 0.18 kW was used to rotate the drum. Rotating speed of the drum was maintained at 30 rev/min. The roasting temperature was controlled by the gas control valve. Any degree (light, medium or full) of roasted coffee could easily be obtained to meet the consumer requirement. A digital thermometer was provided to monitor the temperature inside the roaster during roasting. The average capacity of the roaster was 4.5 kg/h. After roasting, the green bean moisture content (11.83%) was reached to 7.96%, 3.08%, 2.92%, and 8.49% for light, medium, full and fry pan roasted bean, respectively. It was found desirable color for roasted been in the roaster. Cost of roasting was found to be Taka 23 per kg. The use of the roaster would reduce the cost of roasting by 75% over manual roasting.
Burner, capacity, coffee, coffee roaster, temperature
Gazipur,Khagrachari.
Farm Mechanization
(i) To design and fabricate a power operated coffee roaster
(ii) To test the performance of the roaster in laboratory and in the field
(iii) To Make an economic analysis of the coffee roaster
A horizontal rotating drum type coffee roaster was developed in Farm Machinery and Postharvest Process Engineering Division of Bangladesh Agricultural Research Institute during 2011-2012. The following modifications were done to increase its efficiency according to the users demand during 2012-2013. To make it low cost, locally available materials were used in fabrication. Efforts were made to make the machine as simple as possible. To provide the facility for the operator to watch the internal temperature of the roaster at the time of roasting a digital thermometer is attached. This weight of the machine was 16 kg. Ten kilograms of freshly harvested green coffee beans were collected from the coffee garden of Hill Agricultural Research Station, Khagrachari. By adjusting the gas control valve the temperature of the roaster was kept about 200°C. The green coffee beans were inserted in the roaster and switched on the motor for continuous rotation. Roasting time and temperature were maintained for desired degree of roasting. The conditions of the beans were visually observed by the opening of the gate during roasting. The smoke and smell were also observed to understand the degree of roasting. Roasted beans were unloaded immediately and cool quickly after roasting with a blower so that the desired degree of roast can be obtained. Depending on roasting time and temperature, they were processed in three different degrees (light, medium and full roasted). Visual inspection of the external color of the beans is the most common procedure for degree of roast determination. The color of green and roasted coffee samples were measured by a chromameter (CR-400, Minolta Co. Ltd., Japan).
Research Report
(i) A coffee roaster was developed for roasting of coffee beans in the household or small scale industry level.
(ii) The roasting capacity was found 4.5 kg/h considering 3 batches of 1.5 kg per hour.
(iii) Cost of roasting was found for the coffee roaster Taka 23 per kg and it can reduce the cost of roasting by 75.36% over manual roasting.
(iv) The flavors, taste and color of roster roasted coffee were superior to those of fry pan toasted bean.
(v) Different degree of roasted coffee can easily be obtained from this roaster as desired by the consumers.
(vi) This roaster can reduce the drudgery and cost of quality coffee processing in Bangladesh.
Report/Proceedings