Detecting Contaminants and Verifying Weight in Pet Food and Treat Production

Pet food manufacturers often inspect loose or bulk product before packaging using metal detection systems. After bagging, checkweighers verify fill accuracy, and X-ray inspection may be used to inspect finished packages for foreign contaminants. This layered inspection approach allows producers to detect contamination early while also verifying the safety and integrity of the final sealed product.

Pet food manufacturing safety standards can be as strict as, or even stricter than, human food requirements. Industry-wide detection thresholds for contaminants — plus additional requirements from retailers and private-label programs — require manufacturers to ensure their products are free of any foreign object contamination.

Pet food inspection systems are used to detect metal, stone, glass, and other foreign materials before products reach store shelves. Integrating inspection technology into your pet food production and packaging process protects animals, supports compliance, and reduces the financial impact of recalls.

How is Metal Detection Used in Pet Food Manufacturing?

Metal contamination can enter pet food products in more ways than many manufacturers realize. From raw ingredient intake to final packaging, there are multiple opportunities for foreign metal to make its way into the process.

Common sources of metal contamination in pet food manufacturing include:

• Raw ingredients such as ground corn, meat, fish meal, or grains that may contain metal fragments from harvesting or processing equipment
• Supplier-related risks, when incoming materials have not been adequately inspected upstream
• Processing equipment wear and tear, including screens, grinders, mixers, extruders, and conveyors
• Broken tools or loose fasteners
• Clips or metal components used in certain packaging formats, such as chub-style fresh pet food
• Environmental contaminants introduced during bulk handling or transfer

With so many opportunities for contamination throughout the manufacturing process, pet food brands should consider metal detection at several points in their production process.

Raw Ingredient Inspection

Raw ingredient inspection provides an added layer of protection at the front end of pet food production. Some manufacturers choose to inspect incoming raw materials as a verification step alongside supplier quality programs. Screening ingredients before they enter a manufacturing system helps prevent metallic contaminants from moving deeper into the process and reduces the risk of downstream equipment damage.

See how a conveyor belt inspection machine works to reduce contaminants in bulk ingredients.

In-Process Inspection

Metal detection can be installed during processing to catch contamination before the product reaches final packaging. This is especially valuable for:

• Dry kibble using gravity-fall metal detectors before bagging

• Fresh or raw pet food moving through pipelines (such as chub-style products)

• Treats or bulk items prior to being portioned into bags or cartons

Detecting contamination at this stage minimizes product loss. Instead of discarding entire finished packages, manufacturers can isolate and remove smaller quantities of affected product. Earlier inspection also allows systems to detect smaller metal fragments.

Final Package Inspection

Many facilities install metal detection systems after the product has been packaged. Applications include bagged dry pet food, boxed treats, and bulk cartons containing multiple units.

Passing this “final check” validates your process safety and quality control measures and confirms that products leaving your facility are safe.

Looking for impurities in finished packages? A conveyor belt inspection machine might be a perfect choice.

Foil Packaging and Pouches

Maintaining the correct moisture level is critical. Many pet treats and smaller premium pet food products are packaged in flexible pouches or foil-lined bags with a barrier layer that protects the product by controlling moisture, helping extend shelf life.

Because metalized films interfere with traditional metal detection, X-ray inspection is typically implemented at the final package stage.

Finished bags pass through the X-ray system without interference from the packaging material. The system scans the contents inside the sealed package to identify unexpected contaminants while maintaining production speed and product integrity.

This is especially common for:

• Resealable treat pouches

• Foil-lined freshness bags

• Flexible stand-up pouches

Clip-Sealed “Chubs”

Fresh and refrigerated pet food is often packaged in tube-style “chubs” sealed with a metal clip. While in-line metal detection may be used earlier in the process, final inspection after sealing typically shifts to X-ray. The system is configured to recognize and ignore the known metal clip while still identifying unexpected contaminants within the product. This ensures effective inspection without unnecessary rejects.

Aluminum Trays, Mono-Dose Bags, and Canned Wet Pet Food

Wet pet food products are typically packaged in cans, aluminum trays, or aluminum mono-dose bags. While aluminum trays and mono-dose bags can easily pass through conventional X-ray systems, canned dog and cat food requires a more specialized inspection approach. This is because cans are more likely to tip over when passing through heavy shielding curtains.

Curtainless Side-View X-ray Systems are commonly used for upright cans, scanning across the shortest product dimension to enhance detection sensitivity. These systems can also provide quality control benefits, such as validating fill level, helping confirm consistency before labeling and shipment.

Bulk Ingredients

X-ray inspection can also be installed prior to packaging, particularly for treat-style products moving along a conveyor. For example, biscuit or “milk bone” style treats can be inspected before entering the packaging system. By identifying contaminants at the bulk stage, facilities discard only affected pieces rather than an entire finished package or case. This reduces product waste and supports efficient root cause investigation.

Raw Ingredients

Inspection at the raw ingredient stage can reveal risks that may not be immediately visible. In one large pet food operation, X-ray inspection identified stone contamination traced back to fish-based ingredients. Bottom-feeding fish can ingest small rocks, which may travel through processing if not detected in an early-stage inspection before further processing affects overall product control.

Confirm Product Packaging

In addition to detecting and removing contaminants from pet foods, X-ray inspection systems can provide quality and consistency assurance. X-ray systems can be “taught” to recognize abnormalities within a package that would confirm item count, reveal broken or damaged items, or detect underfilled or unfilled packages.