Fate of regulated, masked, emerging mycotoxins and secondary fungal metabolites during different large-scale maize dry-milling processes

The use of maize in the food chain could be mainly limited due to its contamination by mycotoxins. As scarce information is available, the current study is aimed at collecting new data on the co-occurrence and the fate of the most frequent masked, modified and emerging mycotoxins and other second fungal metabolites in maize food products and by-products. Three maize lots, obtained in different growing seasons, were processed using two different degermination processes, a dry-degermination system or a tempering-degermination one, in order to compare the interaction between mycotoxins and the dry-milling management system. Whole grain before and after cleaning, and all the products and the by-products were sampled twice for each lot and were subjected to a multi-mycotoxin LC-MS/MS analysis. More than 30 mycotoxins and other fungal metabolites, including masked or modified forms, co-occurred in all the maize milling fractions. Grain cleaning reduced all the detected fungal metabolites by 1.2–2 times, compared to the grain before cleaning. Animal feed flour showed the highest content of almost all the mycotoxins and fungal metabolites, with a consequent negative impact on animal health. Considering that for all the mycotoxins and fungal metabolites an inverse relationship with particle size was observed, flaking grits represented the healthiest maize products with the least contamination level, while the abatement was always lower for maize flour. Furthermore, the metabolites were variably redistributed in the maize fractions. The total aflatoxins, kojic acid, deoxynivalenol and its modified form, culmorin, and its associated forms, butenolide, fusaproliferin, fusaric acid, fusarinolic acid and, in some cases, zearalenone and its modified forms, and fusarin C were found to be concentrated significantly in the germ. Some of them also had a greater permanence in the maize food fractions and a weaker decontamination, both of which point to a higher risk of exposure for the end consumers. The co-occurrence of a such a high number of mycotoxins and fungal metabolites and their different fates during the dry-milling process have never been described before.