Drying effectiveness and aflatoxin contamination of household stored Agricultural produce at Chamwino, Dodoma

Abstract

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.