Dissertation
In the tropics, agricultural produces experience high post-harvest losses and are prone to
mycotoxins contamination. Environmental conditions coupled with inadequate drying and
storage practices are the major causes of postharvest loss and contamination. Cereals and
oilseeds are more susceptible to aflatoxin contamination. This study aimed at assessing
storage practices, awareness of smallholder farmers on aflatoxins, and walk-in solar dryer
(WSD) as a drying technique to control aflatoxins contamination in cereals, oil seeds and
nuts for improved livelihood of smallholder farmers in Chamwino, Dodoma. Ninety
smallholder farmers in Chamwino were interviewed to assess storage practices and
awareness of aflatoxins contamination in maize, groundnuts and sunflower seeds.
The majority (95.6%) of smallholder farmers stored grains in plastics or synthetic bags
and kept the bags of grains on the floor without pallets. In addition, 88.9% of smallholder
farmers had never heard about mycotoxins and thus are not aware of the health
consequences of consuming aflatoxin contaminated foods. Moreover, most (96.7%) of
farmers interviewed were not aware the fact that feeding animals with contaminated feeds
pass on the toxins to animal products such as meat, eggs and milk.
Immune-affinity High Performance Liquid Chromatography (HPLC) and post column
derivatization was used to analyse AFB 1 , AFB 2 , AFG 1 , AFG 2 and total aflatoxins of
household-stored maize, groundnuts and sunflower seeds samples (n=45). For all samples,
the moisture content levels were within the legal limits; maize (9.57%), groundnuts
(4.13%) and sunflower seeds (5.70%). However, 38% of samples were highly
contaminated with aflatoxins in which mean for maize and groundnuts were 74.91 μg/kg
and 268.82 μg/kg, respectively. On contrary, sunflower seeds had the lowest levels (0.23iii
μg/kg) of total aflatoxins. The maximum level according to Tanzania standards (TZS) or
East Africa Community Standards (EAS) is 10 μg/kg. The highest mean levels of AFB 1
was observed in maize (58.36 μg/kg) and groundnuts (233.48 μg/kg), which is beyond the
legal limit (5 μg/kg). It further, observed that 31.1% of interviewed smallholder farmers
did not sort their grains, and the produces were kept on bare grounds during harvesting
and no pallets on storage.
The WSD had higher mean temperature (41°C) and lower relative humidity (31.2%) than
open-sun drying (temperature 31°C, relative humidity 43.2%). WSD had lower drying
time for all the produce (maize 18 hours, groundnuts 18 hours and sunflower seeds 10
hours) than open-sun drying (maize 20 hours, groundnuts 20 hours and sunflower seeds 16
hours). The final moisture content was statistically significant for all analysed samples.
The average mould Aspergillus flavus (CFU/g) for maize; freshly harvested, dried in WSD
and open sun-drying (OSD) were 4.30, 3.60 and 4.23, respectively (which was within the
limits set in EAS 44-2017). In addition, foreign matter for samples dried on OSD was
significantly (p<0.05) higher (4%) compared to samples dried in WSD (0.65%) which
was exceeded the recommended level of foreign matters set in TZS 438-2018 /EAS 2-
2017 and TZS 740-2018 /EAS 888-2018.
It was concluded that in the studied villages there is limited knowledge on aflatoxins
contamination of stored products and effects of consuming contaminated foods. Training
of smallholder farmers on good agricultural and postharvest handling are recommended to
reduce postharvest losses and assure food security and safety.
Tanzania Industrial Research
and Development Organization