The debranning of common wheat as innovative tool in milling

Debranning is an essential step for removing the hulls of covered cereals and it can be used for removing the outer bran layers in “naked” grains. On the basis of the interesting results obtained with durum wheat, we investigated the possibility to successfully apply debranning to common wheat kernels. At first, a pilot-plant debranning machine equipped with rolls characterized by superabrasive surfaces was used. The technological parameters taken into account were: the particle size of the superabrasive elements, the processing time, the number of debranning passages and the hydration conditions of the kernels before treatment. The amount of waste (expressed as debranning level, DL) and the physical and chemical modifications of kernels associated with debranning were examined. Best results in terms of homogeneous removal of bran layers (DL ≤ 10%) were obtained with the addition of 3% water, keeping the hydrated grains mixed for 5 minutes and applying a short processing time (1 min). Superabrasive surfaces with fine particle size gave a quite uniform debranning process, without deep grooves in the endosperm region. A final brushing of the debranned kernels assured a more accurate removal of bran layers. Debranning levels lower than 8 - 10% allowed to minimize starch losses. The partial removal of the bran layers allowed a relevant reduction of tempering time (up to 90%) without decreasing the flour yield. Furthermore, the technological quality of flour obtained by debranned wheat kernels was comparable to that from conventional milling. Thanks to these encouraging results, debranning had been put in an industrial milling diagram obtaining similar positive results.