Effect of preliminary grinding of the wheat grain on the pulverizing process

This article presents the results of investigations on the pulverizing grinding energy requirements for whole and preliminary ground wheat kernels regarding different moisture levels. Four common wheat cultivars (Triticum aestivum, ssp. vulgare) differing in kernel hardness were used for tests. When the moisture of kernels ranged from 14% to 20% w.b. the lower values of average particle size were obtained for preliminary ground wheat. The pulverizing energy requirements expressed by different grinding indices were considerably lower for preliminary ground kernels rather than for whole kernels. The values of specific pulverizing energy ranged from 32.6 to 79.0 kJ kg⁻¹ for whole kernels, whereas the values of total specific grinding energy (the sum of specific grinding energy and specific pulverizing energy) changed from 23.1 to 44.4 kJ kg⁻¹ for the two-stage ground wheat. In addition, the other values of pulverizing indices confirmed that preliminary size reduction significantly reduced the grinding energy requirements.