A study of the effects of storage methods on the quality of maize and household food security in Rungwe District, Tanzania.
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Date
2011
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Abstract
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.
Description
Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.
Keywords
Maize--Storage--Tanzania., Maize--Quality--Tanzania., Maize--Diseases and pests--Tanzania., Maize--Postharvest losses--Tanzania., Mycotoxins--Tanzania., Insect pests--Tanzania., Food security--Tanzania., Food supply--Tanzania., Households--Tanzania., Theses--Food security.