Assessment of Water‐Based Treatments and Debranning Methods for Removal of Pesticide Residues in Maize Grains and Their Products

Pesticide residues in staple foods pose significant public health concerns, especially in regions with intensive agrochemical use and weak regulatory enforcement. This study examined the presence and reduction of pesticide residues in 75 maize grain samples and their processed products collected from five milling factories in Nyamagana and Ilemela districts, Mwanza Region, Tanzania. Residue extraction was performed using solid–liquid and liquid–liquid methods, followed by quantification via gas chromatography–tandem mass spectrometry (GC‐MS/MS). Sixteen pesticide compounds were identified, including malathion, pirimiphos‐methyl, p,p ′ ‐DDT, p,p ′ ‐DDE, and trichlorfon. Two postharvest treatments, washing (single washing and double washing) and debranning, achieved average residue reductions of 32.92 % ± 11.37 % , 66.74 % ± 11.62 % , and 99.32 % ± 0.32 % , respectively. Combined washing and debranning removed detectable residues in polished ( sembe ) flour. Residue distribution analysis revealed higher concentrations in the outer layer, germ, and tip regions of the grain, underscoring the importance of debranning as a key intervention, despite the associated nutrient loss. However, bran from unwashed maize retained elevated residue levels, risking bioconcentration when used as animal feed. These results underscore the importance of standardized processing protocols and stricter pesticide regulations to enhance food safety and safeguard public health.