Low-cost post-harvest technologies reduce aflatoxin contamination in Rwanda's smallholder peanut value chain

Background Aflatoxin contamination is one of the most significant food safety concerns in peanut supply chains in sub-Saharan Africa, which results in severe health outcomes and the inability to gain access to the market. Although peanut farming in the Eastern Province of Rwanda is one of the major regions, a lack of information about the level of contamination and the feasibility of implementing mitigation strategies through cost-effective solutions is observed. Methods A cross-sectional study was conducted in four major peanut-producing districts (Nyagatare, Kayonza, Gatsibo, and Bugesera). A stratified random sampling was applied to have 60 composite samples in the form of farm and market sources. AOAC standard method was used to determine the total aflatoxin (ELISA), moisture, water activities, crude protein and oil content. The trial was an intervention trial that was conducted as a three-month intervention trial in which the conventional sun drying was compared with the solar drying and the use of Purdue Improved Crop Storage (PICS) bags. Findings: Aflatoxin was observed in 86.7 percent of the samples with 71.7 percent of them above the Codex Alimentarius level of 15 ug/kg and 85.0 percent above the European Union level of 4 ug/kg. There was high variation between the districts (p < 0.001), Kayonza had the highest mean contamination at 22.3 +- 5.1 ug/kg, whereas Gatsibo recorded the lowest at 15.6 +- 4.2 ug/kg. There was a close relationship between aflatoxins and moisture content (r = 0.68, p < 0.001) as well as water activity (r = 0.72, p < 0.001). PICS hermetic storage decreased aflatoxin by 57% and 32% after 3 months, respectively, of traditional sun drying (12.2 vs. 28.5 ug/kg; p < 0.001) and solar drying. Such approaches effectively kept the moisture level below 9% and the water activity below 0.65 without any effect on the nutritional value. Conclusion Aflatoxin pollution is rampant in the peanut chain of supply in Rwanda. Nevertheless, contamination can be significantly minimized through the use of affordable post-harvest technologies, e.g., PICS hermetic storage and solar drying, which can also be used to maintain the quality of products. Based on these findings, it is important to encourage small-scale farmers to use cost-effective drying and storage techniques as a viable measure to enhance food safety and market access.