Applied Research Note: Effects of grinding and pelleting Kernza grain on subsequent particle size, flowability, and pellet durability index

Abstract

Two experiments were conducted to determine the effects of Kernza grain on particle size, flowability, and pellet durability index (PDI). An experiment was conducted to determine the effects of grinding Kernza grain on subsequent particle size and flowability. Three separate hammermill screen sizes, 2.0, 2.8, and 3.6 mm were used to grind Kernza grain. Each treatment was ground at 3 separate time points for a total of 3 replications per screen size. When grinding Kernza grain, particle size analysis showed an increase in geometric mean diameter, d_gw, (linear, P < 0.001) as screen hole diameter increased from 2.0, 2.8, to 3.6 mm. However, as d_gw increased with increasing screen hole diameter, the standard deviation, S_gw, (linear, P < 0.021) decreased. As the d_gw increased, Kernza grain AoR increased (linear, P < 0.001). With the resulting AoR values of Kernza grain ground with a screen size of 2.0 mm and 2.8 mm this product would classify as a poor flowing material (46–55°). However, as the screen size increased to 3.6 mm and subsequent particle size increased, the AoR value decreased determining this product as a passable flowing material (41–45°). Pelleting conditions yielded an increase (linear, P < 0.01) in Δ temperature as the inclusion of ground Kernza grain increased. As the inclusion of Kernza grain increased, subsequent PDI increased (quadratic, P < 0.001). Pellet durability increased from 58.6% in the control diet to 88.4% in the 30% Kernza grain diet. The largest increase in pellet durability occurred between the 0 and 10% inclusion ranges where there was a 20% increase in pellet durability. From 10% to 30% inclusion, pellet durability still increased, but at a decreased rate of only 10%.