Effect of milling procedures on mycotoxin distribution in wheat fractions : a review

Cereals and cereal by-products constitute a major part of human and animal diet. It has been estimated that up to 25% of the world’s crops may be contaminated with mycotoxins. The relevance of mycotoxins on human/animal health prompted the European Community to introduce maximum permissible limits in foods and feeds. Considering the levels indicated by the European legislation, results from literature indicate that sometimes the limits proposed for cereal-derived products may be not warranted by the limit for unprocessed cereals. Therefore, the understanding of how mycotoxin distribution and concentration change during the milling process is a worldwide topic of interest due to the high economic and health impact. This paper reviews the most recent findings on the effects of wheat milling process on mycotoxin distribution in products and by-products. Published data confirm that milling can minimize mycotoxin concentration in fraction used for human consumption, but concentrate mycotoxins into fractions commonly used as animal feed. The concentration of mycotoxins in wheat by-products may be up to eight-fold compared to original grain. Other physical processes carried out before milling, such as sorting, cleaning, and debranning, may be very efficient to reduce the grain mycotoxin content before milling. Published data show a high variability in mycotoxin repartitioning and sometimes appear conflicting, but this may be mainly due to the type of mycotoxins, the level and extent of fungal contamination, and a failure to understand the complexity of the milling technology. A precise knowledge of such data is vital and may provide a sound technical basis to mill managers to conform to legislation requirements, support risk management and regulatory bodies in order to reduce human and animal exposure to mycotoxins, reduce the risk of severe adverse market and trade repercussions, and revise legislative limits.