Receive and grind
Size reduction so cooking is uniform. Material goes in fresh, never held over from the previous day.
By-products
Meat and bone meal
This is the business line most meat plants currently pay to dispose of. Processed properly, bone and trim become saleable protein, saleable fat, and a second invoice on raw material that has already been bought.
Control parameters
| Variable | Value | Why |
|---|---|---|
| Raw material | Bone, trim and fit offal | Only material from animals fit for consumption. Condemned material follows another route and cannot enter animal feed. |
| Freshness | Process within 24 h | By-product degrades fast. Old raw material yields meal with high volatile nitrogen and an odour no customer accepts. |
| Sterilisation | 133 °C, 3 bar, 20 minutes | The international reference standard for by-products destined for feed. Destroys pathogens and prions. |
| Pressing | Tallow separation | The fat is extracted and sold separately. Above 12 % left in the meal, it goes rancid and loses value. |
| Milling | 2 – 3 mm screen | Particle size affects mixability at the customer’s feed mill. |
| Microbiological control | Salmonella absent | The test that decides whether the lot ships or gets reprocessed. Not negotiable. |
Process
Step by step, with the temperatures.
Cook and sterilise
Digester at 133 °C and 3 bar for 20 minutes. Three phases separate here: solids, fat and water.
Press
Separates liquid fat (tallow) from the protein solid. The tallow is filtered and stored apart: it is product, not waste.
Cool and mill
The solid is cooled and milled to target particle size.
Stabilise
Antioxidant added to protect residual fat. Without it the meal goes rancid within weeks.
Test and release
Protein, fat, ash, moisture, pepsin digestibility and Salmonella. No lot leaves without analysis.
| Control point | Value |
|---|---|
| Crude protein | 45 – 50 % |
| Fat | 8 – 12 % |
| Ash | 28 – 35 % |
| Calcium | 8 – 12 % |
| Phosphorus | 4 – 6 % |
| Calcium:phosphorus ratio | ≈ 2 : 1 |
| Pepsin digestibility | > 85 % |
| Final moisture | < 8 % |
Troubleshooting
What went wrong, and why.
Half the craft is reading the defect. These are the ones that keep coming back.
| What you see | What caused it |
|---|---|
| Persistent putrid odour | Raw material waited too long before entering the digester. Neither process nor antioxidant corrects it. |
| Low digestibility | Excess temperature or time: the protein overcooks and the animal no longer uses it. More cooking is not more safety. |
| Rapid rancidity | High residual fat with no antioxidant. Fixed by pressing better and stabilising. |
| Salmonella positive | Recontamination after the digester: plant flow crosses raw with finished material. A design problem, not a cooking problem. |
| Ash out of range | Uncontrolled bone-to-meat ratio. The inbound mix has to be standardised for constant composition. |
Frequently asked
What people ask before they start.
Is it legal in animal feed?
It depends on the target species and the country. The universal restriction is the ban on feeding ruminant protein to ruminants, which comes out of the BSE crisis. For poultry, pigs and pets it is widely used, with whatever origin traceability the regulation demands. Check your country’s rules before selling.
How much raw material makes it viable?
Rendering is a scale business: equipment carries high fixed cost and margin comes from volume. Before investing, measure how many tonnes a day your plant genuinely produces — and those of the area, since it often pays to process by-product from several abattoirs.
Which is worth more, the meal or the tallow?
It depends on the market and the moment. That is why a well-designed plant sells both: tallow moves into feed, soap and biodiesel, and meal into compound feed. Designing for a single output exposes you to a single market price.
Contact
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