Feed Cooling and Drying (Post-Extrusion)

Pellets leaving an extruder or dryer carry significant residual heat and moisture from the conditioning and cooking process, and cooling and drying equipment, typically a counter-flow or cross-flow cooler-dryer using ambient or slightly heated air, brings the pellet down to a stable moisture content (generally below about 10-11 percent for shelf-stable storage) and to a temperature close to ambient before bagging or bulk storage, a step that is not optional cosmetic processing but a direct determinant of whether the finished feed will resist mold growth and maintain its physical structure during storage and transport. Drying too aggressively or too quickly can case-harden the pellet surface while leaving the core moist, creating a pellet that appears dry on inspection but develops internal mold or loses structural integrity during subsequent storage, while insufficient drying leaves overall moisture high enough to support mold growth and accelerate lipid oxidation in oil-coated pellets, both failure modes that may not become visible until well after the feed has left the mill. Cooling rate also affects pellet durability directly, since a pellet cooled too rapidly can develop internal stress cracking that increases fines generation during subsequent handling even though the pellet appeared intact immediately after cooling. Mills producing high-fat, vacuum-coated pellets typically sequence cooling before the oil coating step specifically so the coating is applied to an already-stabilized pellet rather than one still releasing heat and moisture that could destabilize the coating or encourage oxidation of the freshly applied oil.