“What should I feed my pet” usually turns into a conversation about brands. Before we get anywhere near brands or which type is better, it’s worth understanding something more basic: not all pet food is processed the same way, and the differences aren’t subtle once you know what to look for.
This isn’t a “processed bad, fresh good” post. That conversation is coming, and it deserves its own space. This one is simpler: what actually happens to food between “raw ingredient” and “what lands in the bowl,” across the different types you’ll see on a shelf.
The spectrum, from most processed to least
1. Extruded dry kibble
The most heavily processed category, and the most common. Ingredients are ground, mixed into a dough-like mixture, then forced through a machine (an extruder) under high heat and high pressure, which cooks and expands it into the familiar kibble shape before it’s dried and often coated with fats and flavouring to improve palatability. The high heat and pressure are what make kibble shelf-stable at room temperature for long periods.
2. Canned / wet food
Ingredients are mixed, sealed into the can, then heat-sterilised (retorted) at high temperature to make it shelf-stable — a different heat process from extrusion, but still a significant thermal processing step. Moisture content is far higher than kibble, which is one of the most meaningful practical differences between the two categories.
3. Freeze-dried and dehydrated
Ingredients are prepared (often lightly cooked, sometimes raw) and then have moisture removed either through freeze-drying (very low temperature, moisture removed via vacuum) or dehydration (low, steady heat over time). Both extend shelf life without the same intensity of thermal processing as extrusion or canning. Freeze-drying in particular preserves more of the original structure of the ingredient.
4. Gently cooked / fresh-cooked
Ingredients are cooked at lower temperatures for shorter periods, closer to home cooking than industrial processing, then usually refrigerated or frozen rather than shelf-stabilised. Less processing intensity, but a shorter shelf life and different storage requirements as a trade-off.
5. Raw
Minimally processed, typically just ground, portioned, and frozen for safe handling and storage. No cooking step at all. This is the least industrially processed end of the spectrum, though “raw” covers a wide range of actual preparation and sourcing quality.
What’s actually different between these, mechanically
Setting aside which is “better” for a moment, here’s what genuinely changes as processing intensity increases:
- Moisture content — dramatically different between dry kibble (roughly 10%) and canned, fresh, or raw foods (often 60–80%).
- Heat exposure — how much, at what temperature, and for how long, which affects the structure of proteins, fats, and nutrients differently depending on the method.
- Shelf-stability method — what allows the food to sit on a shelf (or in a fridge, or freezer) safely, and for how long.
- Ingredient form — whole and recognisable, versus ground, rendered, or reconstituted from meals and concentrates.
Where this is going next
In upcoming posts, we’ll go further into what actually happens chemically during higher-heat processing: things like the formation of Advanced Glycation End-products (AGEs), oxidation of fats, the addition of higher carbohydrate content to make extrusion possible, and the role of synthetic preservatives, flavourings, and colourings. We’ll also look at the value of fresher, less-processed ingredients, and where the real trade-offs are between convenience, cost, shelf-stability, and nutritional quality.
For now, the goal is just to be able to look at any pet food and correctly place it on this spectrum, because that’s the foundation everything else builds on.
