nutrition
Kibble extrusion
What happens inside an extruder
- Wet dough, ground ingredients are mixed with water and steam into a thick, pliable mass.
- Cook and shear, the dough is forced through a screw barrel at 90–150 °C and several megapascals of pressure for 10–60 seconds, gelatinizing starch and denaturing protein.
- Die and cut, at the exit, sudden pressure drop causes the dough to expand; a rotating knife slices the rope into pellet shapes.
- Dry, coat, cool, pellets pass through a drier to under 10% moisture, then receive a sprayed coating of fat and palatants before bagging.
How cooking changes the nutrient profile
Extrusion improves starch digestibility and inactivates some anti-nutritional factors. It also degrades heat-sensitive vitamins (notably some B-vitamins and vitamin C, where added) and can reduce the bioavailability of certain amino acids, particularly lysine through the Maillard reaction with reducing sugars. Manufacturers compensate by over-formulating the affected nutrients on the dry mix or spraying them on after cooling.
Non-extruded alternatives
- Baked kibble, lower temperature, longer time; denser pellet, less expansion.
- Cold-pressed, pellets formed under pressure with limited heat; common in European brands.
- Air-dried and freeze-dried, water removed from raw or cooked ingredients without re-cooking.
- Wet/canned, retort-sterilized in the can; different nutrient-loss profile than extrusion.
Why it matters
Most marketing copy treats extrusion as a dirty word, but the alternatives carry their own trade-offs in cost, shelf life, and pathogen control. The cooking method matters less than whether the manufacturer accounts for its effects in the final formulation.
Frequently asked questions
- Does extrusion destroy enzymes?
- Yes, most native enzymes are denatured by extrusion temperatures. This is irrelevant to the animal, whose digestive system makes its own enzymes and does not depend on dietary ones for any documented benefit.
- Is extruded food less nutritious than raw?
- Not categorically. Extrusion-related nutrient losses are compensated in formulation; raw diets carry their own losses (oxidation, nutrient imbalance) plus pathogen risk. Both can be nutritionally complete when designed correctly.