A study of the effects of storage methods on the quality of maize and household food security in Rungwe District, Tanzania.

Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

A sample of 260 farm households that were randomly selected in Katumba ward, Rungwe district, Tanzania were studied for the effects of storage methods on the quality of maize grain and household food security using qualitative and quantitative methods. Maize storage problems, amounts of maize that farm households harvested and amounts of maize that farm households lost to pests per year, food security status and farm households’ perceptions concerning their food security status were investigated using face - to - face semi - structured and structured interviews. Common storage methods that farm households used to store maize and the dietary importance of maize were investigated through interviews, seasonal calendars and the matrix for scoring and ranking. The quality of maize was investigated through conducting mycological analysis and through investigating levels of insect infestation using the incubation method on maize samples collected from a sub-sample of 130 farm households at harvest and after five months of storage period. It was found that farm households in Katumba ward preferred maize meal rather than other types of food that provide bulk such as rice and green bananas/plantains. Maize contributed 66.8 % - 69.5 % of the total energy and 83 - 90 % of the total protein required per day, and farm households stored maize using roof and sack storage methods. It was also found that 34.5 % of 2323 tonnes of maize that were harvested per annum in Katumba ward were lost to pests during storage. Fusarium, Diplodia, Aspergillus and Penicilliums species were identified as the main fungal pathogens that attacked stored maize. Sitophilus zeamais, Sitotroga cerealella and rodents were also identified as the main maize storage pests. About 25 % of the maize samples that were collected at harvest and 93 % of the maize samples that were collected from the same farm households after five months of storage were infested by either Sitophilus zeamais or Sitotroga cerealella or both. Maize samples from the two storage systems had an average number of 80 insect pests per 120 maize kernels (or 51 g of maize), amounting to 1569 insects per kg. The high levels of insect infestation reduced the amount of maize that could have been available to the farm households and subjected stored maize to fungal infections and subsequent contaminations, thus, rendering the farm households vulnerable to food insecurity. Furthermore, it was also found that most of the infestation of maize by insect pests and moulds in Katumba ward occurred during storage, and that farm households were not well informed concerning maize storage and the negative effects that fungal activities in maize can have on the health of the consumers. An average of 87717 μg/kg fumonisins, 596 μg/kg aflatoxins, 745 μg/kg ochratoxins and 1803 μg/kg T-2 toxins were detected in the maize samples. Currently, there are no set standards for T-2 toxins, whereas the internationally accepted standards for aflatoxins, fumonisins and ochratoxins in cereals are 20 μg/kg, 4 mg/kg and 50 μg/kg, respectively. It was concluded that the levels of mycotoxins detected in maize from Katumba ward were far above the internationally accepted standards and that the farm households were at risk of ill health through consuming maize meals made from contaminated maize grain. The presence of high concentrations of mycotoxins, together with the high levels of insect infestation in the maize led to the conclusion that reduction of the nutrient content of the maize grain in Katumba ward was inevitable. Thus, the pests that infested maize stored using the roof and sack storage methods in this ward compromised not only the availability of food, but also the utilization of the nutrients in the maize and its safety, leading to the farm households’ food insecurity. It was further concluded that the quality of maize stored using roof and sack storage methods in Katumba ward was low and that the roof and sack storage methods were inadequate for protecting stored maize from pests. It was recommended that an efficient method for rapid drying of maize prior to storage be found, that the roof and sack storage methods be improved so that they can effectively protect stored maize from moisture content problems. It was also recommended that the farm households’ awareness concerning maize storage and food security be raised, and that the extension staff in Katumba ward should urge the Tanzanian government to implement an agricultural policy which promotes efficient maize storage and maize quality in order to improve the current status quo. Above all, since maize is the predominant staple, it was recommended that the maize breeding program in Tanzania should emphasize development of maize varieties that are resistant to ear rots, storage insects and to contamination by mycotoxins as part of a larger program to improve food security in this part of the country. Breeding programs that aim at enhancing the nutritional value of maize were also recommended.