Investigation of the spatial arrangement of mycotoxin build-up in corn stored under different environmental conditions

Authors: KERRY, RUTH - Brigham Young University; INGRAM, BEN - Brigham Young University; ABBAS, HAMED; AHIBORNE, GENE - Brigham Young University

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Food crops are often spoiled in the field and in storage settings by fungi growing on them. The fungi can produce toxins like aflatoxin which is extremely carcinogenic. Due to the adverse health effects of these fungal produced toxins, the levels permissible in food stuffs are legislated. When food stuffs like grain are tested for mycotoxin levels, several samples are taken from the grain mass and mixed so that just one sample has to be analysed. This approach is used because testing is expensive, but it assumes that the whole grain mass has the uniform average level of toxin. It also assumes that there is no spatial patterns in the stored grain of where the toxins build up. Previous research suggested that toxin build-up may be greatest at the base and edges of grain piles as these are likely to be the dampest and most aerated locations where the fungi can respire more and produce more toxin. If this is the case, then high and low-risk areas within the stored grain can be identified so they can be tested separately, and farmers do not have to waste whole batches of grain or sell them at minimal price as biofuel. They could potentially sell the grain from low-risk zones at a higher price. Identifying consistent spatial patterns in toxin build up can also be helpful to those in less developed countries where only food for export is tested. Knowing which areas of stored grain are more likely to be contaminated will help improve food safety in the absence of testing. We set up bins of clean and contaminated corn in different environmental conditions and stored bins of grain for two months. We put 12 Carbon dioxide, moisture, temperature sensors in 3 layers in each bin of grain with some sensors being at the center and edge of the bin in each layer. After two months of storage the levels of 4 toxins were measured in corn located next to the sensors. As expected, there were higher levels of toxins in edge locations and also in the bottom layers of the storage bins with the data for some toxins showing significant differences between areas. There were also higher levels of toxins when the grain was stored at temperature and humidity levels that favour the growth of specific fungi and toxin production. This was exploratory work to help determine if this research is worth pursuing further and what range of environmental conditions bins should be stored at for future experiments. The results suggest that these experiments should be repeated for a larger range of temperatures and relative humidities and that the highest risk zones are at the base and edges of grain storage bins.

Technical Abstract: Mycotoxins are toxins produced by fungi that contaminate many key food crops as they grow in the field and during storage. Specific mycotoxins are produced by different fungi. Each type of fungus and mycotoxin have their own optimal temperatures and water activities for growth and production. The legislative limits for various mycotoxins in foodstuffs to protect human health vary between countries but all commodities have their levels evaluated based on the concentrations from one aggregated grain sample. This approach assumes that the variation in toxin levels is uniform and random without trends spatially. Previous research showed that levels of fumonisins trended higher towards the moister bottoms and oxygenated edges of stored grain piles. As a proof of concept, this study investigates the spatial distribution of four mycotoxins (aflatoxin, deoxynivalenol, fumonisin and zearalenone) in bins of clean and dirty corn when stored in an environmental cabinet for two months under different temperature and humidity conditions. The bins of clean and dirty corn each had 12 CO2/humidity/temperature sensors installed in 3 layers and samples were extracted for mycotoxin analysis from locations close to each sensor following storage. Significant differences were found between mycotoxin levels attributable to different environmental conditions and spatial locations of samples. Variations in aflatoxin and zearalenone concentrations were most pronounced for the range of temperature and humidity conditions chosen. By understanding the patterns of spatial variability in mycotoxin concentrations and identifying zones at high risk of contamination as well as what conditions are favourable, targeted interventions could be implemented to reduce food waste.