Effects of industrial processing on the distributions of deoxynivalenol, cadmium and lead in durum wheat milling fractions

The aim of this work was to investigate the distributions of deoxynivalenol, cadmium and lead in durum wheat milling fractions from industrial milling plants. The study focused on two milling technologies: conventional milling and debranning before milling. Initial analyses of samples of all raw materials showed contamination levels considerably lower than the limits imposed by the European Commission. Deoxynivalenol, cadmium and lead showed rather similar patterns of distribution. Semolina had lower, although not significant levels of these undesirable substances than unprocessed wheat grain; in contrast, marked concentration factors were found for the contaminants in shorts (middlings) and flour shorts. Debranning technology resulted in higher contamination levels in products intended for animal feed than conventional milling. The difference was statistically significant for deoxynivalenol and lead contamination of the shorts (middlings) fraction. As the outer parts of the kernel are generally considered richer in inorganic elements and moulds, Pearson's correlation was performed to investigate the relationship between the crude fibre contents of the different fractions, adopted as bran marker, and contaminant levels. Positive correlations were found for each of the three contaminants, although the correlation coefficients were not very high, demonstrating that crude fibre likely does not constitute a good marker for describing contaminants repartitioning in milling fractions when the levels of these substances are low.