Résumé
The milling behavior of two naturally infected samples from durum wheat grains displaying contrasting levels of mycotoxins were analyzed. Although the two samples showed a similar milling behavior, an increase of about twenty percent in deoxynivalenol level was found in semolina from the sample containing the higher amount of mycotoxins. However, even if the highest concentration of deoxynivalenol was found in fractions originating from the grain outer layers, the mycotoxin contamination in semolina and flours were not related to the amount of two biochemical compounds (ash or phytic acid) that could be used as markers to monitor these external tissues. Presence of the trichothecene-producing fungi in the most internal semolina fraction was also shown using specific DNA primers and PCR amplification. Comparison between deoxynivalenol concentration in the feedings and corresponding output at each milling step or grinding of semolina fractions followed by sizing showed that mycotoxin concentration occurs in the finest particles at the first processing steps. Therefore, deoxynivalenol contamination of the milling fractions is not simply due to the presence of peripheral grain tissues.