Fundamental factors in feed manufacturing: Towards a unifying conditioning/pelleting framework

This paper discusses some more fundamental properties associated with the physical quality of pelleted animal feed. The focus is on concepts used in chemistry, physics and soft matter research to discuss the impact of time on heat and water diffusion into particles in the conditioning/pelleting process. It is argued that the extent of transformation of feed components as for instance starch is limited by the availability of water and that the distribution of water in the feed mash particle is governed by particle size, water diffusivity and the time available for hydration in the conditioning process. The role of the glass transition in altering the apparent viscosity of the feed mash resulting in a change of the compaction characteristics of the feed mash is discussed. Bond types in feed agglomerates consist of capillary forces during the compaction phase (pelleting) and transform to solid types of bonds during cooling. Overall, time dependent processes as indicated above give rise to observed differences in the final physical pellet quality and observed systems parameters in feed manufacturing.