Assessment of post harvest handling practices of maize at Odumase in the Sunyani west district of the Brong Ahafo Region
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Date
2009-08-10
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Abstract
Aflatoxin contamination levels were measured in samples collected from selected maize stores at the beginning and at the end of the storage period to examine the incidence of aflatoxin in Odumase (a major maize producing and marketing centre) and the effect of different storage practices. A mean contamination level of 61.6ppb was found in the 25 samples collected with 72% of the samples having contamination levels in the 20-100ppb range. The mean contamination level in the beginning of storage samples was 26.7ppb and increased to 56.7ppb in the end of storage samples after a period of 3 to 5 months. A survey conducted through the administration of a questionnaire to 42 farmers showed that storage of ears in traditional cribs was the predominant practice with 88.1% of respondents using this storage practice. Storage of husked maize in the traditional cribs showed no increase in aflatoxin contamination levels but storage of dehusked ears in the traditional cribs recorded a mean change of 90ppb over the storage period. The survey identified good handling and storage practices in the research area, such as the sorting out of mould infected and insect damaged ears as well as treatment of both maize and storage structures with insecticide. High increases in insect infestation in most stores at the end of the storage period suggested lack of professionalism in the use of good storage and handling practices. The research identified low patronage of certified seed (14.3%) and fertilizer (7%) among farmers and the undue delay in conveying harvested maize from the farm gate to the farmers’ store or the market (average of 11.6 days) as situations contributing to the high pre-storage aflatoxin level of 26.7ppb. Fungal evaluation in maize samples also showed the presence of Aspergillus flavus in all but two of the beginning of storage samples. Analysis of climatic data of the research area and moisture content data on maize from the Odumase market indicated the existence of unfavourable climatic conditions for maize handling during the harvesting period of July to September/October. Relative humidities of above 80% leave harvested maize with moisture contents between 26.8% and 18% and make sun drying of little effect. The survey revealed that mechanical drying was not practiced by farmers themselves but some poultry farmers and traders who buy maize from the Odumase market. The research concluded that mechanical drying would be the most effective way of dealing with the high aflatoxin contamination levels, in view of the unfavourable climatic conditions especially during the major season harvest. It was also concluded that strict observance of good agronomic and post harvest handling and storage practices could significantly reduce the aflatoxin contamination level even without mechanical drying.
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A thesis submitted in fulfilment of the requirements for the Mphil in food and post harvest Engineering.