Effectiveness of hermetic technologies in limiting aflatoxin B1 and fumonisin B1 contamination of stored maize grain under smallholder conditions in Zimbabwe

Abstract

There is limited empirical evidence on the efficacy of hermetic storage containers in reducing mycotoxin occurrence in stored maize grain under smallholder field conditions. Levels of aflatoxin B1 (AFB1) and fumonisin B1 (FB1) in maize samples collected from hermetic metal silos (148), hermetic grain bags (121) and conventional stores (179) during 2015 and 2016 storage seasons in two rural districts of Zimbabwe were assessed. AFB1 was determined using high performance liquid chromatography with post-column derivatisation and fluorescence detection, whilst FB1 was determined using direct competitive ELISA. All maize samples collected at harvest in 2015 and 2016 seasons contained FB1 at levels ranging from 10 to 462 μg/kg and 13 to 537 μg/kg, respectively. Use of hermetic containers did not seem to have any effect on the development of FB1 in stored maize grain, as there was no significant difference (P>0.05) in the increase of FB1 contamination in hermetic and conventional stores. Prior to storage, the levels of AFB1 in the maize ranged from below the limit of quantitation (LOQ) to 25.0 μg/kg, whilst levels during storage ranged from <LOQ to 8.60 μg/kg in hermetic silos, <LOQ to 8.37 μg/kg in hermetic bags and <LOQ to 791 μg/kg in conventional stores over the two storage seasons. The occurrence of AFB1 in maize stored in hermetic containers, was significantly (P<0.05) lower than that in conventional stores. Hermetic containers were more effective than conventional stores in limiting contamination of maize with AFB1 and subsequent human exposure to these toxins. Therefore, hermetic storage containers are recommended to smallholder maize producers for safe and effective limitation of AFB1 contamination during storage and hence reduce exposure among consumers.