The Improved Ahotor Oven
Fish processing is the main economic activity for women living in and around the coastal and lake areas of Ghana. Preservation methods include salting, frying and freezing, but smoking is the most prevalent form: practically all species of fish available in the country can be smoked and it is estimated that 75% of the domestic marine and freshwater catch is processed this way. Most processed fish is sold in major markets across the country and within the West African region, with some products making their way through to the global diaspora.
Contributing to high rates of deforestation in coastal Ghana is the widespread use of inefficient fish smoking technologies, with the most popular being the Chorkor stove (Figure 1), first identified, developed and scaled in Ghana in 1969 by the FAO together with government institutions. However, using this technology, women work under often strenuous conditions (exposure to heat and smoke) and for marginal incomes. The World Health Organization estimates that harmful cookstove smoke is the fifth leading cause of death in developing countries.
Contributing to high rates of deforestation in coastal Ghana is the widespread use of inefficient fish smoking technologies, with the most popular being the Chorkor stove (Figure 1), first identified, developed and scaled in Ghana in 1969 by the FAO together with government institutions. However, using this technology, women work under often strenuous conditions (exposure to heat and smoke) and for marginal incomes. The World Health Organization estimates that harmful cookstove smoke is the fifth leading cause of death in developing countries.
Figure 1: A Chorkor Stove in use. The same basic design is now used throughout West Africa.
Figure 2: The Improved Morrison stove adds a number of energy efficient features
The smoking and drying techniques of the Chorkor stove have limitations that deserve greater attention in order to significantly improve small-scale fishers’ livelihoods and respond effectively to product safety challenges – especially linked to controlling contamination by polycyclic aromatic hydrocarbons (PAH), a public health hazard. PAH are carcinogenic, fat soluble, nonvolatile and extremely persistent, and develop especially during the incomplete combustion of organic materials. Globally, PAH levels in food are monitored by regulatory agencies with a combination of four compounds (PAH4) being of specific interest: benz[a]anthracene, chrysene, benzo[b]fluorantene and benzo[a]pyrene. Under EU food standards, the level of PAH4 in smoked food products should not exceed 12 µg/kg and for benzo[a]pyrene (BaP) 2 µ/kg.
Recent SFMP analyses have shown that smoked fish from Chorkor ovens contain PAH levels that is quite alarming and may render the smoked fish unwholesome for human consumption. For instance, the BaP dose calculated for smoked Engraulis encrasicolus from Chorkor oven ranged from 22 to 44.39 μg/kg/day-1.
Recent SFMP analyses have shown that smoked fish from Chorkor ovens contain PAH levels that is quite alarming and may render the smoked fish unwholesome for human consumption. For instance, the BaP dose calculated for smoked Engraulis encrasicolus from Chorkor oven ranged from 22 to 44.39 μg/kg/day-1.
Improved low-PAH Smoking Stove Development
In response to the research findings, USAID under the SFMP committed funds to develop a series of low-PAH and energy efficient stove models. The stove technology development was carried out by a team of local and international consultants with guidance from SNV, Food Research Institute and the Fisheries Commission, and with testing support from the Ghana Standards Authority and the Institute of Industrial Research of CSIR.
The result of the test was the development of the Ahotor or Comfort oven. The technology has a grate in the oven on which the fuelwood lies. This part of the technology enhances complete combustion, which results in drastic reduction in smoke emission and use of less fuelwood. Another feature of the Ahotor oven is a fat collecting tray which is fitted on top of the combustion chamber that allows the hot gases to flow up through to the fish while preventing fat, blood and water from dripping into the fire, which was the source of higher PAH formation. A PAH analysis showed that the stove achieved 0.6 µg/kg and 10.93 µg/kg for BaP and PAH4 respectively, considerably lower than the Chorkor and meets the EU standards (Figure 3). In addition the Ahotor oven is 32% more fuel efficient than the Chorkor.
In response to the research findings, USAID under the SFMP committed funds to develop a series of low-PAH and energy efficient stove models. The stove technology development was carried out by a team of local and international consultants with guidance from SNV, Food Research Institute and the Fisheries Commission, and with testing support from the Ghana Standards Authority and the Institute of Industrial Research of CSIR.
The result of the test was the development of the Ahotor or Comfort oven. The technology has a grate in the oven on which the fuelwood lies. This part of the technology enhances complete combustion, which results in drastic reduction in smoke emission and use of less fuelwood. Another feature of the Ahotor oven is a fat collecting tray which is fitted on top of the combustion chamber that allows the hot gases to flow up through to the fish while preventing fat, blood and water from dripping into the fire, which was the source of higher PAH formation. A PAH analysis showed that the stove achieved 0.6 µg/kg and 10.93 µg/kg for BaP and PAH4 respectively, considerably lower than the Chorkor and meets the EU standards (Figure 3). In addition the Ahotor oven is 32% more fuel efficient than the Chorkor.
Fig 4: The Improved Ahotor Oven
