Development of a solar cocoa processing centre for cooperative use in Indonesia

Sri Mulato, . and Atmawinata O., . and Handaka, . and Pass T., . and Muehlbauer W., . and Esper A., . Development of a solar cocoa processing centre for cooperative use in Indonesia. pp. 57-74. ISSN 0126-575X

The production and export of cocoa beans is of great importance for the Indonesian economy. Due to the lack of appropriate fermentation and drying technologies the cocoa produced by smallholders is of low quality and therefore is discounted on the international markets. To overcome the existing postharvest problems the introduction of centralised processing centre operated on cooperative level seems to be the most promising alternative. Within a bilateral Indonesian-German research project a Solar Processing Centre was developed. The centre consists of a low cost substructure in which fermentation drying grading and storage can be conducted simultaneously under the same roof. The yearly capacity amounts to 85 tonnes of dried cocoa beans which is sufficient to serve around 100 farmers. To substitute the scarce and expensive firewood presently used as fuel for operating high temperature dryers on the private or governmental estates a 144 sq m solar air heater is incorporated into the roof. The Solar Processing Centre can be operated by solar energy without any supplement heater at a daily insolation more than 5kWh per sq m. Due to the high thermal efficiency of 45 to 50 per cent in the operating range of the solar air heater this insolation level is sufficient to provide the required moderate drying air temperature of 45-50 degree celcius at a humidity of 15-20 per cent. Fermentation boxes and flat bed dryers are arranged step wise to enable simply gravity discharge of the beans. Five days fermentation procedure was interrupted by only one mixing interval instead of daily mixing as practised currently on large plantations. Based on investigations on the optimum drying methods to achieve the desired high fructose and glucose content which is an important factor for proper development of the chocolate flavour during subsequent roasting the flat bed dryers were operated at significantly lower temperature compared to the conventional drying method. For generating a constant air flow necessary to assure the uniform and continuous moisture removal the dryers are equipped with a newly designed low cost axial flow fan. The blade is originally used in cooling fans of trucks. The efficiency of this fan is around 40 per cent at an air flow rate of 1750 cu m per hour and static pressure of 130 Pa while its electrical power consumption is less than 400W. The investigation showed that the fermentation and the drying process could be improved significantly within the Solar Processing Centre in terms of quality drying time energy consumption and economical aspects. The drying time was shortened by one third to 80-96 hours compared to sun drying the electrical power consumption required for driving the fans decreased from originally 90-100 kWh per tonne to 25-30 kWh per tonne whereas the production cost per kg dried cocoa beans was diminished from Rp250 to 92. The product quality in terms of chocolate flavour and sweetness is close to those benas of high quality produced in Ghana. Acidity is slightly more than Ghana cocoa but remarkably lower than cocoa beans produced by conventional artificial dryers in Indonesia.

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Abstract

The production and export of cocoa beans is of great importance for the Indonesian economy. Due to the lack of appropriate fermentation and drying technologies the cocoa produced by smallholders is of low quality and therefore is discounted on the international markets. To overcome the existing postharvest problems the introduction of centralised processing centre operated on cooperative level seems to be the most promising alternative. Within a bilateral Indonesian-German research project a Solar Processing Centre was developed. The centre consists of a low cost substructure in which fermentation drying grading and storage can be conducted simultaneously under the same roof. The yearly capacity amounts to 85 tonnes of dried cocoa beans which is sufficient to serve around 100 farmers. To substitute the scarce and expensive firewood presently used as fuel for operating high temperature dryers on the private or governmental estates a 144 sq m solar air heater is incorporated into the roof. The Solar Processing Centre can be operated by solar energy without any supplement heater at a daily insolation more than 5kWh per sq m. Due to the high thermal efficiency of 45 to 50 per cent in the operating range of the solar air heater this insolation level is sufficient to provide the required moderate drying air temperature of 45-50 degree celcius at a humidity of 15-20 per cent. Fermentation boxes and flat bed dryers are arranged step wise to enable simply gravity discharge of the beans. Five days fermentation procedure was interrupted by only one mixing interval instead of daily mixing as practised currently on large plantations. Based on investigations on the optimum drying methods to achieve the desired high fructose and glucose content which is an important factor for proper development of the chocolate flavour during subsequent roasting the flat bed dryers were operated at significantly lower temperature compared to the conventional drying method. For generating a constant air flow necessary to assure the uniform and continuous moisture removal the dryers are equipped with a newly designed low cost axial flow fan. The blade is originally used in cooling fans of trucks. The efficiency of this fan is around 40 per cent at an air flow rate of 1750 cu m per hour and static pressure of 130 Pa while its electrical power consumption is less than 400W. The investigation showed that the fermentation and the drying process could be improved significantly within the Solar Processing Centre in terms of quality drying time energy consumption and economical aspects. The drying time was shortened by one third to 80-96 hours compared to sun drying the electrical power consumption required for driving the fans decreased from originally 90-100 kWh per tonne to 25-30 kWh per tonne whereas the production cost per kg dried cocoa beans was diminished from Rp250 to 92. The product quality in terms of chocolate flavour and sweetness is close to those benas of high quality produced in Ghana. Acidity is slightly more than Ghana cocoa but remarkably lower than cocoa beans produced by conventional artificial dryers in Indonesia.

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Item Type:	Article
Additional Information:	Summary (En)
AGROVOC Term:	COCOA BEANS
AGROVOC Term:	PROCESSING
AGROVOC Term:	FERMENTATION
AGROVOC Term:	DRYING
AGROVOC Term:	SOLAR ENERGY
AGROVOC Term:	PRODUCTION
AGROVOC Term:	QUALITY
AGROVOC Term:	EXPORTS
AGROVOC Term:	ECONOMICS
AGROVOC Term:	INDONESIA SEMILLA DE CACAO
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:52
URI:	http://webagris.upm.edu.my/id/eprint/17796

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