How kibble is made: extrusion, fat coating, and what it means for your pet

You read the ingredient list on the bag: "fresh chicken, peas, sweet potato, salmon oil". The list is reassuring. But between those raw ingredients and the dry, crunchy kibble in your dog's bowl, something significant happens. A high-temperature industrial process, under pressure, with a final coating engineered to make the product irresistible.

Understanding how kibble is made changes the way you read a label. And it explains why two products with similar ingredient lists can have very different effects on your pet's health. Version française : Comment sont fabriquées les croquettes.

The six-step process

Kibble manufacturing follows a standardised industrial sequence regardless of brand. The quality differences come down to the details within each step.

Step 1: ingredient sourcing and reception

Everything starts before the factory. Ingredients arrive in very different states:

Fresh meats: delivered refrigerated or frozen within 48-72 hours of slaughter. "Fresh" in a label context specifically means previously unfrozen.
Dehydrated meats (meals): pre-cooked and dried, with 95 percent of their moisture removed. Highly concentrated in protein (65-70 percent crude protein).
Grains and legumes: delivered in bulk and stored in silos. Corn, rice, wheat, barley, peas, lentils depending on the formula.
Fats and oils: chicken fat, salmon oil, linseed oil - stored in separate tanks.
Vitamin/mineral premixes: concentrated synthetic blends added in small quantities to complete the nutritional profile.

Quality at this stage varies enormously. "Fresh chicken" can come from a traceable supply chain with known geographic origin, or from an aggregator with no traceability. Transparent brands like Orijen or Acana publish regional suppliers. Mass-market brands like Royal Canin do not.

Step 2: grinding and mixing

Solid ingredients are ground to a uniform particle size (approximately 200-500 microns). This fine grinding is required for the next step. Fresh meats are ground raw; meals are pre-ground already.

Everything is then mixed in an industrial dosing system according to the exact recipe. This is where the relative proportions of each ingredient are fixed. Formulation software calculates quantities to hit nutritional targets (protein, fat, moisture, vitamins) while minimising formula cost.

That last point matters: formulation minimises cost. In mass-market brands, this means quality ingredients can be substituted with cheaper equivalents as long as nutritional targets are met. It is legal, it is common, and it is a reason to read labels carefully.

Step 3: extrusion (140-180°C, 20-40 bar)

Extrusion is the central step in the process. The wet mixture (25-35 percent moisture) is forced into an extruder - a heated cylinder with an internal rotating screw. Friction from the screw and external heat bring the mixture to 140-180°C under 20-40 bar of pressure within a few seconds.

At the die (the nozzle at the extruder exit), pressure drops suddenly. The water in the mixture vaporises instantly - this is the expansion that gives kibble its characteristic porous texture. The kibble shape is determined by the die shape: round, star, triangle.

What extrusion destroys:

Heat and pressure degrade some nutrients. This is not a nutritional catastrophe - kibble remains a complete food - but it is a reality that manufacturers actively compensate for:

Nutrient	Heat sensitivity	Extrusion impact	Compensation
Vitamin C	Very high	60-80 percent loss	Post-extrusion addition or boosted premix
B vitamins (thiamine, B6)	High	20-50 percent loss	Synthetic vitamin premix
Vitamin E	Medium	10-30 percent loss	Antioxidants added + premix
Vitamin A	Low	5-15 percent loss	Standard premix
Essential amino acids	Variable	Lysine -5 to -15 percent	Formulated with surplus
Digestive enzymes	Very high	Total destruction	Not compensated in standard formulas
Omega-3 fatty acids	High	Partial oxidation	Oil added post-extrusion

The "list of synthetic vitamins" at the end of an ingredient label is therefore not a sign of low quality in itself - it is the necessary technical response to extrusion losses. All brands, including the premiums, require it.

Step 4: drying and cooling

Kibble exits the extruder with 25-30 percent moisture. A hot-air tunnel oven brings this down to 8-10 percent - the target for long-term storage without refrigeration.

Drying adds a second wave of heat, longer but less intense (80-120°C for 15-30 minutes). Heat-sensitive vitamins continue to degrade at this stage.

Cooling then brings kibble back to ambient temperature before coating. Insufficient cooling would cause condensation during coating, which would harm preservation.

Step 5: fat coating and flavouring (the step manufacturers don't advertise)

This is the least documented step in any brand's communication, and probably the most interesting for understanding why your dog eats kibble with enthusiasm.

The dry, porous kibble exiting the oven is intrinsically unpalatable. Heat has destroyed most of the natural aromas. To make the product appealing, manufacturers apply an external coating composed of:

Rendered animal fat: chicken, pork, or beef fat, melted and sprayed hot onto the kibble which partially absorbs it.
Meat digest: enzymatic hydrolysate of animal tissues (viscera, carcasses). An intensely aromatic liquid or powder that carnivores find extremely appealing.
Flavourings: natural or nature-identical aromatic molecules added to amplify olfactory appeal.

The result: kibble that releases a strong and appetising smell, and that your pet eats happily even if the internal ingredients are mediocre. This is the exact mechanism that explains why a dog might prefer low-grade kibble over nutritionally superior food: the external coating overrides internal composition in immediate olfactory perception.

The practical implication: if your dog refuses a better-quality new kibble (switching from Royal Canin to a premium brand, for instance), it is not because they "prefer" the lower-quality food. It is because they are conditioned to the aromatic coating of the previous product. A gradual transition over 7-10 days generally resolves this.

Step 6: packaging

Cooled and coated kibble is automatically weighed and packaged. Packaging plays a genuine nutritional role: it must protect fats from oxidation and kibble from moisture.

The best packaging uses multi-layer bags with an oxygen barrier (aluminium or EVOH). Edgard and Cooper's cardboard boxes are recyclable but less airtight. The difference shows in freshness after opening: 4-6 weeks for cardboard, 6-8 weeks for hermetically sealed plastic.

What this means practically

What the process explains about labels

Synthetic vitamin/mineral premixes appear in all kibble, including the most premium. This is a technological necessity, not a quality indicator. What matters is the quality of the vitamin forms used (bioavailability varies significantly by chemical form).

"Fresh chicken as first ingredient" is an excellent sourcing quality signal, but it does not mean the kibble contains 40 percent fresh meat by final weight. Fresh meat loses 75 percent of its weight in cooking. An ingredient listed at 30 percent raw becomes approximately 7-8 percent in the final dry product. This is why premium brands combine fresh meat and dehydrated meat: the two contributions added together give the real animal content.

The ingredient order is calculated on pre-extrusion weight (wet weight). After drying, a high-moisture ingredient (like fresh meat) loses weight relative to dry ingredients (like grains). This is why "rice" or "corn" can end up more dominant by dry weight than it appeared when reading the label.

Understanding protein content claims

A formula listing "38 percent crude protein" is measuring total nitrogen content, not digestible protein. Digestibility varies: animal-source protein averages 85-90 percent digestibility, plant-source protein 70-80 percent. A 38 percent protein formula where 80 percent comes from chicken delivers more bioavailable amino acids than a 40 percent protein formula where 30 percent comes from peas or corn.

This is why we weight animal protein origin heavily in our PetFoodRate scoring methodology - it is a better predictor of nutritional value than the crude protein percentage alone.

Alternatives to extrusion

Extrusion is not the only manufacturing method. Others exist with different nutritional profiles.

Cold pressing

Cold pressing uses mechanical pressure at low temperature (60-80°C maximum). Less thermal degradation, better preservation of heat-sensitive nutrients. The texture is denser and less porous than extruded kibble.

Advantages: nutritional profile closer to raw ingredients, fewer synthetic vitamins required. Limitations: shorter shelf life (6 months vs 12-18 months for extruded), higher price, fewer brands available.

Air drying

The method used by ZIWI Peak: ingredients are dried at 35-40°C for 48-72 hours. Temperature never exceeds 40°C, preserving virtually all heat-sensitive nutrients and natural enzymes.

The final product resembles kibble visually but has a softer texture. Nutritional density is exceptional: a daily ZIWI Peak ration represents roughly 50 percent of the volume of a standard extruded kibble ration for the same nutritional input.

For a comparison of air-dried scores, see our best dog food 2026 ranking.

Freeze drying

Freeze drying removes moisture at very low temperature under vacuum. No heat involved - nutrient preservation is maximal. The result is a light, crumbly product with a nutritional profile very close to raw.

Drawbacks: very costly process, high price per kilo, fragile product, often requires rehydration before serving.

Baked

Some brands use low-temperature oven baking (120-140°C) rather than extrusion. Less pressure, gentler thermal treatment. Shape differs - typically biscuit-style or irregular nuggets rather than uniform kibble.

Process comparison

Method	Temperature	Duration	Nutrient preservation	Relative price	Availability
Extrusion	140-180°C	Seconds	Moderate	Base (1x)	Everywhere
Cold pressing	60-80°C	Minutes	Good	x1.5-2	Limited
Air drying	35-40°C	48-72 h	Very good	x3-5	Online
Freeze drying	-40°C vacuum	24-72 h	Excellent	x5-10	Online/specialist
Baked	120-140°C	20-40 min	Good	x1.5-2	Online
Raw	None	-	Maximum	x4-8	Fresh/frozen

How to choose based on the manufacturing method

For the best quality/price balance in extruded kibble

Choose a brand with fresh plus dehydrated meat as first ingredients, a high total animal content, and a quality vitamin premix. Ultra Premium Direct and Edgard and Cooper are our references in this segment.

If maximum nutrient preservation is your priority

Air drying offers the best compromise between nutritional preservation and convenience. ZIWI Peak is the global benchmark - 96 percent animal content, drying at 38°C, zero grains, zero sugars. Cost is high but daily rations are small (density is 3 times that of kibble).

For dogs with digestive issues or food sensitivities

Cold pressing or air drying reduce exposure to the thermal degradation that can affect sensitive dogs. The link between high-temperature extrusion and intestinal irritation is not definitively established scientifically, but some dogs respond positively to switching to less thermally processed foods. For dogs with severe digestive problems, consult a vet or veterinary nutritionist before changing diet.

Fat coating and palatability: the full picture

The fat coating mechanism explains a lot of observed eating behaviours that puzzle owners.

A dog that "loves" a low-grade kibble and "refuses" a better premium one is not making a conscious nutritional choice. It is responding to olfactory signals from the external coating. The meat digest used in industrial coatings is formulated to trigger maximum olfactory response - it is palatability engineering.

Premium kibble also uses coatings (natural fats, oils, flavourings), but generally with better-quality fats and less aromatic artifice. They can seem "less appealing" at first to a dog conditioned to intensive industrial coatings. This is temporary - after 2-3 weeks on the new product, adaptation occurs.

For a smooth transition: replace 20 percent of the usual kibble with the new one on day one, 40 percent on day three, 60 percent on day five, 80 percent on day seven, 100 percent on day ten.

Packaging and post-opening freshness

An often overlooked aspect: the fats in the coating oxidise after opening. Oxidation produces rancid compounds that reduce palatability and, over time, nutritional value (degradation of essential fatty acids).

Best practices:

Store kibble in its original packaging, not a plastic container that can retain residual odours
Seal tightly after each use
Avoid large formats if turnover is slow
Never mix new with old in the same container

For air-dried or freeze-dried products, oxidation is faster after opening (larger exposure surface). These products typically keep 4-6 weeks after opening versus 6-8 weeks for well-packaged extruded kibble.

What the label does not legally have to tell you

European regulation on pet food labelling leaves significant grey areas that manufacturers exploit legally.

"Chicken" can mean very different things. Legally, "chicken" can include muscle meat, offal (liver, heart, lungs, kidneys), fat, and bone (for meals). Without specifying "chicken fillet" or "chicken meat", you do not know which part is used. Premium brands specify ("fresh chicken fillet", "chicken liver") - budget brands use the generic term.

"Natural flavourings" can refer to any aromatic compound of natural origin, with no obligation to specify the source. It is an open door for the industry. Good brands specify "natural chicken flavour" or simply do not need flavourings at all.

Ingredient percentages only apply to marketing claims. If a bag says "rich in chicken" or "with chicken", the manufacturer must declare the percentage of chicken. But if there is no marketing claim on a specific ingredient, no percentage is required. This is why premium brands voluntarily display their percentages - it is a transparency signal, not a legal obligation.

"Grain-free" does not necessarily mean low carbohydrate. Peas, lentils, sweet potato, and cassava can replace grains as starch sources. A "grain-free" kibble with 45 percent peas can have a similar carbohydrate profile to a rice-based kibble. Grain-free is a marketing argument more than an absolute nutritional guarantee.

EU regulation: what actually protects your pet

European regulation 767/2009 on pet food covers several important aspects:

Mandatory labelling: nutritional values (protein, fat, fibre, moisture, crude ash), ingredient list, target species, feeding instructions.
Prohibitions: dangerous substances, contaminants above defined thresholds, unlisted ingredients.
Controls: member states conduct official checks on commercial formulas.

What regulation does not cover: ingredient quality within a legal category. "Poultry meal" can be a high-quality meal (yield from a premium abattoir) or a minimum-quality meal (undifferentiated abattoir by-products). Both are legal. The difference in nutritional value and digestibility is real but unregulated.

This is why voluntary transparency from premium brands is genuinely valuable: it goes beyond the legal minimum to provide information that regulation does not force.

How to read a label in 5 minutes

Here is the method we use at PetFoodRate to analyse a label efficiently:

1. First ingredient: identifiable fresh or dehydrated meat? If it is a grain or a vague by-product, the formula is not premium.

2. The top 5 ingredients: what is the visible animal proportion? If 3 of the first 5 ingredients are identifiable animal-source, that is a positive signal.

3. Carbohydrate sources: whole rice > corn > wheat > grain brans > corn plus wheat plus barley combined. Legumes (peas, lentils) are a good grain-free alternative for most dogs.

4. The additives list: synthetic vitamins and minerals are expected and necessary. Artificial colourants (E102, E110, E120, E124, E129, E132, E133, E142, E151, E155, E160d) are unnecessary and undesirable. Artificial preservatives (BHA, BHT, ethoxyquin) should be avoided.

5. The declared analysis: crude protein ideally above 28 percent, fat above 12 percent, crude fibre below 5 percent. High crude ash (above 9 percent) can indicate a high bone content in the formula.

For automated scoring of any product against these criteria, see our product database covering more than 300 references.

Wet food vs kibble: how manufacturing changes the picture

Wet food (pouches, tins) follows a completely different manufacturing process that is worth briefly covering for comparison.

Wet food is processed at lower temperatures (typically 110-125°C in a retort/autoclave) for shorter durations. The high moisture content (70-80 percent vs 8-10 percent for kibble) acts as a thermal buffer. Nutrient preservation is moderately better than extrusion.

The main advantages of wet food:

Higher hydration (beneficial for kidney health and urinary tract)
Typically higher meat content by wet weight
Shorter ingredient lists, less processing

The main limitations:

Higher cost per daily ration once water content is discounted
Less convenient (needs refrigeration after opening)
Dental benefits of kibble (mechanical friction) are absent

For a comparison of wet and dry options, see our best wet dog food 2026 and best wet cat food 2026 guides.

The bottom line

Every kibble on the market is extruded. The process is not inherently good or bad - it is the industrial reality of a product that needs to be shelf-stable, convenient, and affordable. The quality differences come from what goes in before extrusion (ingredient quality), how carefully the process is run (temperature control, timing), and what is added back afterwards (vitamin quality, coating source).

When you read "fresh chicken as first ingredient" on an Edgard and Cooper bag or a ZIWI Peak pouch, the manufacturing journey that ingredient took to become the product in your hand is fundamentally different. One was processed at 160°C under 30 bar of pressure. The other was dried at 38°C for two days. Both are valid; they are not equivalent.

For a ranked list of kibble and alternative foods by score, see our complete product database.

Sources

Zicker SC - Evaluation of pet foods: beyond the ingredients list - Topics in Companion Animal Medicine - scientific review on thermal processing effects on nutrients in animal nutrition
FEDIAF - European Pet Food Federation - Code of Practice for the manufacture of safe pet food - manufacturing standards and quality criteria
Murray SM et al. - Selected extrusion cooking conditions affect starch and nitrogen digestion - J Anim Sci - impact of extrusion parameters on digestibility
Hand MS, Thatcher CD, Remillard RL - Small Animal Clinical Nutrition, 5th edition - Mark Morris Institute - academic reference on clinical animal nutrition
AAFCO - Official Publication - Ingredient definitions and nutritional profiles - official ingredient definitions and US nutritional standards

Max Kowalski, Animal nutrition and food science expert, PetFoodRate