Association of farmers’ sorghum grain postharvest handling practices with aflatoxin B1 and total fumonisin contamination in East Hararghe, Ethiopia

Abstract

Improper farmers’ postharvest handling practices of sorghum grain coupled with adverse climatic conditions are conducive for fungal growth and toxin production. The objective of the present study was to investigate the association of farmers' sorghum grain postharvest handling practices with aflatoxin B1 and total fumonisin contamination in three districts (Babile, Haramaya and Kersa) of East Hararghe Zone, Ethiopia. A total of 90 sorghum grain samples were collected in two phases. Half of the total samples were collected from the threshing yards at the time of threshing and the other half of samples were collected from  underground storage pits 5 - 6 months after storage in the year 2013/14. Quantification of the mycotoxins was done using  enzyme-linked immunosorbent assay (ELISA). Farmers threshed their sorghum grain either on bare ground, on cow dung smeared ground or on canvas while the underground storage pits were differently managed in all the three study districts. Variation in mycotoxin contamination levels were evidenced from sorghum grain threshed on different grounds. The highest mean (8.52 μg kg^-1 grain) aflatoxin B1 and mean total fumonisin (1085.1 μg kg^-1 grain) were detected from Babile sorghum grain samples threshed on bare ground. The highest total fumonisin (2002.8 μg kg^-1grain) was detected from Haramaya sorghum grain samples threshed on bare ground close to the farmers’ sorghum fields. The variation was also observed in sorghum grain samples collected from the underground storage pits. High levels of aflatoxin B1 and total fumonisin were recorded from sorghum grain samples collected from bare underground storage pits in all the three study districts. Use of bare underground storage pits for sorghum grain storage showed a high risk of mycotoxin contamination. The findings of this study call for intervention strategies to be
implemented by subsistence farmers to reduce the contamination by aflatoxin B1 and total fumonisin.

Keywords: Aflatoxin, ELISA, Fumonisin, Grain, Mycotoxins, Postharvest, Sorghum, Toxin