The Effect of Hammer Mill Screen Size on Processing Parameters and Starch Enrichment in Milled Barley

Abstract

The influence of two levels of hammer mill screen size on processing parameters and the effect of barley particle size, after segregation by sieving, on starch content and bulk density were examined. Barley grains were hammer-milled through a 2mm and 6mm screens and subsequently fractionated on a set of eight sieves size 0.045, 0.125, 0.250, 0.5, 1.0, 1.7 and 2.8mm. The purposes of this study were to characterize the influence of hammer mill screen size (2 and 6mm) on processing parameters: production output, energy consumption, average particle size (dgw), geometric standard deviation (sgw) and to characterize the influence of particle size, after segregation by sieving, on starch enrichment and bulk density. The results of this study show that increasing the hammer milling screen size has resulted in a significant effect on production output, energy consumption, dgw with no effect on sgw. Different particle sizes, when segregated by sieving, have shown significant effect on starch content and bulk density. Particle size retained by sieve size 1mm had the highest starch content, whereas particles retained by sieve size 0.25mm had the lowest, which suggest potential applications in ruminant and monogastric nutrition. Different measurements of bulk density of segregated particle size suggest the possibility of size fractionation of milled barley particles based on their density differences.