Mycotoxin Reduction in Maize by Industrial-Scale Cleaning Solutions.

Maize is the most important food crop in the world, although it is largely susceptible to mycotoxin contamination causing a negative economic impact and serious health risks to humans and animals. It is well-known that moldy, colored/discolored, injured, broken and damaged grain kernels, as well as dust within a contaminated batch of maize, contain high levels of mycotoxins. A combination of cleaning technologies to efficiently remove contaminated fractions can therefore significantly reduce mycotoxin contamination in the outcome product. Different batches of biomass/feed quality maize contaminated by aflatoxins and Fusarium toxins (namely deoxynivalenol, fumonisins and zearalenone) have been processed on different industrial plants in Italy, Germany and Spain to evaluate the effect of different cleaning solutions on the reduction of mycotoxins. The investigated cleaning solutions included i) mechanical size separation of coarse, small and broken kernels, ii) dust/fine particles removal through an aspiration channel, iii) separation of kernels based on gravity and iv) optical sorting of spatial and spectral kernel defects. A dynamic sampling according to the Commission Regulation No. 401/2006 was performed along the entire process lines. The frequency of sampling was estimated according to the DG-SANCO guidance by taking in account the number of incremental samples, the weight of portion to be sampled (ton) and the unloading speed (ton/hr). A number of incremental samples ranging from 3 to 60 (about 100-300 g each) was collected, depending on the sampled fractions. Mycotoxin analyses of the water-slurry aggregate samples were performed by validated HPLC methods based on immunoaffinity column clean-up of extracts. In addition, in some trials the incoming materials were analyzed by the Eurofin's Rapidust® system for on-site sampling of dusts. A significant reduction of mycotoxin content in the cleaned products was observed for aflatoxins (up to 90%), zearalenone (up to 88%), deoxynivalenol (up to 82%) and fumonisins (up to 69%), with respect to the uncleaned products. High levels of mycotoxins were found in the rejected fractions, with the highest levels in dusts and in the rejected fractions from aspirator and optical sorting. This study shows that a cleaning line combining both mechanical and optical sorting technologies can provide a reliable solution for reducing mycotoxin contamination in maize. In addition, a completely new sorting technology was recently developed by Bühler for grain cleaning and monitoring based on the spectral properties of fluorescence to reduce the risk of aflatoxin contamination in maize.