Effect of debranning on T-2 and HT-2 toxin content in durum wheat kernels and milling fractions

Grains and grain-based products provide the largest contribution to the sum of HT-2 and T-2 toxin exposure for humans and their monitoring is of high priority. The European Commission has recently published a recommendation on the presence of T-2 and HT-2 toxins in cereals and cereal products. An indicative level of 50 ?g/kg has been fixed for the sum of T-2 and HT-2 toxins in durum wheat (Triticum turgidum ssp. durum Desf.) and other cereals for direct human consumption. Wheat debranning, a process by which outer kernel layers are removed through both friction and abrasive scouring actions, positively affects several quality features of semolina such as the improvement of milling yield and the reduction of heat damage. Moreover, the same process provides a powerful tool to improve hygienic-sanitary quality of derived products. Aim of the present study was to evaluate the effectiveness of debranning process to reduce the levels of T-2 and HT-2 toxins in treated kernels and milling fractions. A durum wheat sample contaminated with T-2 and HT-2 toxins at level of 122 ?g/kg (sum of T-2 and HT-2 toxins) was subjected to two consecutive debranning steps at laboratory scale, each one of the duration of 30s. Debranned and not-debranned kernels were processed by a pilot milling plant. All samples, including debranned kernels, debranning wastes and milling fractions (semolina, coarse bran, fine bran and fine middlings) were analysed for the sum of T-2 and HT-2 toxins by enzyme-linked immunoassay (Veratox® for T-2/HT-2, Neogen) and by LC-MS/MS after immunoaffinity column clean up. Results showed that the debranning process significantly reduced levels of T-2 and HT-2 toxins in the kernels with a reduction rate of 72% after the first 30s step. No significant toxin reduction was observed after the second 30s debranning step. High mycotoxin levels were found in the debranning wastes. The semolina fractions, after 0.4 mm sieving, obtained from both debranned and unprocessed kernels showed not significant differences in toxin content, suggesting an accumulation of these toxins in the most peripheral layers. Interestingly, coarse bran obtained from debranned kernels at first step (30s) resulted to be less contaminated (201 µg/kg) than that obtained from unprocessed kernels (433 µg/kg). Preliminary results obtained in the present study indicate that the debranning process is useful to reduce T-2 and HT-2 toxin contamination present on the surface of the wheat kernel and could play an important role to obtain whole-wheat products or less refined products with high nutritional value and hygienic-sanitary quality.