Effects of grinding and pelleting Kernza® grain on subsequent particle size, flowability, and pellet durability index

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 mm, 2.8 mm, and 3.6 mm were used to grind Kernza® grain. Each treatment was ground at three separate time points for a total of three replications per screen size. When grinding Kernza® grain, particle size analysis showed an increase in geometric mean diameter, dgw, (linear, P < 0.001) as screen hole diameter increased from 2.0 mm, 2.8 mm, to 3.6 mm. However, as dgw increased with increasing screen hole diameter, the standard deviation, Sgw, (linear, P < 0.021) decreased. As the dgw 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%.