Prevention of toxigenic fungal growth in stored grains by carbon dioxide detection

Abstract

The growth of toxigenic fungi can adversely affect grain quality and even produce mycotoxins of food safety concern, which should be sensitively monitored and controlled during grain storage. To establish the relationship between the growth of toxigenic fungi and their carbon dioxide (CO2) production, the pattern of CO2 concentration changes was studied during the fungal growth in grain. The results showed the CO2 concentrations increased exponentially (r ≥ 0.96) during the growth of toxigenic fungi Aspergillus flavus, Penicillium sp. and Aspergillus ochraceus, which was different from the linear increase of CO2 concentration produced by the non-toxigenic xerophilic fungi Aspergillus glaucus and Aspergillus restrictus. The acceleration of CO2 concentration was found much earlier than the growth of toxigenic fungi, which would be useful for the prevention of grain spoilage. In addition, the CO2 concentration changes were also determined in storage containers loaded with grain of different moisture content and significant correlation (p < 0.05) was found between changes of CO2 concentration and fungal growth as well as mycotoxin production. The nonlinear increase of CO2 concentration in stored grains could be considered as an indication of the rapid growth of toxigenic fungi and greater risk of microbial spoilage of grains. The results can provide a valid foundation for the prevention of toxigenic fungi and mycotoxin production in stored grains through monitoring the CO2 concentration changes.