Ochratoxin A levels in cocoa nibs from western north, western south, Ashanti and Brong Ahafo, cocoa growing regions of Ghana

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June, 2015
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Ochratoxin A (OTA), a potent toxin is a secondary metabolite produced by filamentous fungi of the genera Aspergillus and Penicillium present in a wide variety of foodstuffs. Ochratoxin A can contaminate a wide variety of foods as a result of fungal infection in crops, in the field during growth, at harvest, in storage and in shipment depending on environmental conditions especially when they are not properly dried. As these toxicants can never be completely removed from the food supply, many countries have defined levels in food that are unlikely to be of health concern. Since Ghana is one of the leading exporters of cocoa worldwide, it is therefore necessary to monitor the levels of OTA in cocoa beans to determine whether the cocoa beans produced in Ghana conform to international standards. Fifty seven (57) cocoa beans samples obtained from selected districts in four regions of Ghana were analysed using HPLC with a fluorescence detector. The range of concentrations obtained were 0.06 to 2.193 μg/kg (mean- 0.698) for Ashanti; 0.261 to 1.859 μg/kg (mean- 0.933) for Brong Ahafo; 0.186 to 1.557 μg/kg (mean- 0.928) for South western and 0.393 to 4.650 μg/kg (mean- 1.802) for North Western regions. From the results of the study, 93% of the samples had OTA concentrations below the draft standard of 2 μg/kg proposed by EU for cocoa beans and 7% had concentrations above the draft standard of 2 μg/kg proposed by EU. North Western region recorded the highest OTA level of 4.650 μg/kg for samples from Sefwi Kaase from North Western region and the lowest OTA concentration of 0.063 μg/kg was recorded for samples from Forikrom from the Ashanti region. The low levels of OTA detected in this study suggest that exposure of OTA to humans through consumption of cocoa beans from the areas under study is unlikely to be of health concern.
A dissertation submitted to the Department of Chemistry Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirement for the degree of MPhil. Analytical Chemistry College of Science, 2015