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

M. Thomasa, A.F.B. van der Poelb
a Zetadec, Agrobusiness Park 44, 6708PW, Wageningen, the Netherlands
b Animal Nutrition Group, Wageningen University & Research, P.O. Box 338, 6700 AH Wageningen, the Netherlands
Received 12 December 2019; Received in revised form 22 May 2020; Accepted 6 July 2020


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.

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