Grinding performance of wheat, maize and soybeans in a multicracker system

This manuscript presents the effects of a recent technology for particle size reduction using a new approach in which the cracking action of two rows of discs is used. Wheat, maize and full fat soybeans were ground by a multicracker system to study the effects of disc type (ceramic versus steel discs), disc speed in revolutions per minute (2650 versus 3800 rpm), throughput (3.43 versus 6.70 metric t/h) and the gap between the discs (0.11 versus 1.04 mm). Mean particle size, width of the particle size distribution curve and total and specific mechanical energy consumption were the dependent variables under investigation.Maize, soybeans and wheat had different grinding characteristics (P<0.001) in the multicracker system with mean particles sizes of 1.76, 2.10 and 2.08 mm, respectively; the width of the particle size distribution, however, being not different for the different seeds. The mean particle size of the initial whole ingredient divided by the mean particle size of the ground samples, referred to as the reduction ratio differed largely (P<0.001) between the seeds. For maize, soybeans or wheat the reduction ratio was 4.53, 2.76 and 1.71, respectively. All particle characteristics of the ground ingredients (mean particle size, width of the particle size distribution and reduction ratio) were not affected by the capacity of the installation in the range of 3.43–6.70 t/h. Soybeans showed the highest specific mechanical energy (2.8 kWh/t) at the highest mean particle size compared to maize and wheat (2.1 and 1.8 kWh/t, respectively).Disc type was examined to be an important variable that largely affects (P<0.001) all particle characteristics as well as the consumption of specific mechanical energy, steel discs revealing the lowest energy requirements.