Incidence of mycotoxin producing fungi and aflatoxins in maize grains and flour in Arua District.

A thesis submitted to the Directorate of Research and Graduate Training, in partial fulfillment of the requirements for the award of the Degree of Master of Science (Botany) of Makerere University

The maize value chain in Uganda lacks mechanisms that ensure grain and flour quality and safety. The objective of this study was to assess the safety of maize and maize flour produced in Arua district with respect to fungal and aflatoxin contamination. A survey to establish the production and handling practices of maize grains and flour was conducted in January 2016, using questionnaires. Fifty farmers and 50 millers were interviewed using the questionnaires. The maize farmers and millers interviewed provided maize and maize flour samples. One hundred samples of maize grains and 100 samples of maize flour were obtained from farmers and millers in Logiri and Omugo sub-counties. Moisture content and fungal contamination were determined by the oven method and mycological procedures respectively. Aflatoxin quantification was by AflaTest® Fluorometer following the manufacturer's instructions. Regression analysis was performed between the different production, handling and processing practices and aflatoxin contamination of maize. Results indicated that the mean moisture content of maize grains and flour were below 13.5%. Four fungal genera namely: Aspergillus, Penicillium, Fusarium and Rhizopus, were isolated. Aspergillus was the most isolated genus in the samples. The mean aflatoxin levels of the maize grains and flour were 9.59 ppb and 15.85 ppb respectively. The occurrence of aflatoxins in stored maize was significantly associated with eight practices out of 19 namely: heaping maize on bare floor (p = 0.003), storage by hanging on trees (p = 0.001), shelling maize by beating (p = 0.007), drying maize on bare ground (p = 0.002) and delayed harvesting (p = 0.007) increased aflatoxin contamination whereas crop rotation (p = 0.047), planting improved seeds (p = 0.010) and sorting maize before storage (p = 0.001) reduced aflatoxin contamination. The study indicated that the people in Arua district are chronically exposed to aflatoxin contamination. The findings are important for policy makers and development partners in designing strategies to prevent maize contamination with aflatoxins.