Assessment of dehulling efficiency to reduce deoxynivalenol and Fusarium level in durum wheat grains

The potential of dehulling to reduce mycotoxin level in two durum wheat grain samples naturally infected by Fusarium and showing contrasting levels of deoxynivalenol was examined using a pearling process. Curve plots expressing mycotoxin decrease against grain mass removal were shown to display a biphasic behavior. A sharp reduction of the deoxynivalenol level was observed at the first pearling steps (i.e. a 45% loss of deoxynivalenol for a 10% grain tissue removal) followed by a slower decrease to reach a level below 30% of remaining mycotoxin when about 35% of the grain tissue was removed. The same type of effect was also observed for reduction of Fusarium in grains analyzed by real-time polymerase chain reaction. Changes in the slope of the curves corresponding either to mycotoxin or fungi loss were found to be located between testa and aleurone layers or in the aleurone tissue, which is in accordance with the current knowledge of the fungi penetration in wheat grains. Furthermore the pearling process was proved to be more efficient than milling to reduce the grain deoxynivalenol content. These results were related to the different ways used by these distinct technologies for grain fractionation.