Factors influencing aflatoxin contamination in maize at harvest and during storage in Kongwa district, Tanzania

A DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN FOOD QUALITY AND SAFETY ASSURANCE OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA. 2017The factors influencing aflatoxin contamination in maize at harvest and during storage in three villages of Manungu, Mlanga and Kongwa in Kongwa district, Dodoma region, Tanzania, were investigated in the year 2015/2016. The villages were chosen as they were major maize producers and suppliers to the international Kibaigwa grain market located in this area. The number of maize samples analyzed were 91. Twenty three samples were taken during harvest and stored for 90 and 180 days in Purdue Improved Crop Storage bags and polypropylene bags. At harvest (30% (7 out of 23) of maize samples were contaminated with aflatoxins. After storage for 90 days of storage 41% (13 out of 32) of the samples were contaminated with aflatoxins while after 180 days of storage, 67% (12 out of 36 samples) were contaminated with aflatoxins. Aflatoxin contamination in all maize samples was above maximum tolerable limit of 10 µg/kg by East African Standards, thus posing a health hazard to consumers. Parameter estimates from generalized linear model (GENMOD) indicated that total aflatoxins increase with time and the concentration was 13.12, 14.75 and 19.39 µg/kg at day 0, 90 and after 180 days of storage, respectively. The effects associated with higher aflatoxin contamination in post harvest management practices were storage duration, storage type, sorting, treatment of stores and treatment of crops. The storage technique with high risk of aflatoxin development was polypropylene bags without pesticides treatment. Maize stored in polyethylene bags (uncontrolled) for 180 days showed increase in aflatoxin levels with mean value of 19. 06 µg/kg. Low aflatoxin was related to the use of insecticides, sorting and use of Purdue Improved Crop Storage bags (PICS) with a mean of 5.4 µg/kg at 180 days. Proper pesticide application reduces the likelihood for infestation, while the use of improved bags (PICS) had shown minimum/low increased levels of aflatoxin contamination in maize