Meat Processing Product Inspection Equipment FAQs

Some meats can include buckshot, hooks or other large metal contaminants that will damage grinding and slicing machines downstream. In addition, equipment can wear down on break off and screws, nuts, bolts, broken mesh, and other metal pieces can fall onto the conveyor while meat is being processed. These contaminants should never reach the customer, as they are a safety factor, and can damage a company’s brand.

Meat products have high product effect—meaning they have conductive properties that can mimic a foreign object, and cause the detector to incorrectly signal a physical contaminant. This false positive often necessitates a compromise in sensitivity to avoid false rejections. With temperature, salt content and product size changing during processing, product effect can vary, too, making consistent foreign object detection difficult. It also poses an ongoing challenge to avoid excessive false rejects which increase the potential for costly scrap or rework. Metal detectors must be able to ignore this product effect to avoid a false rejection.

Most meat-based products will exhibit high product effect in an electromagnetic field resulting in metal detection performance significantly worse than detecting contaminants in dry, inert products. Some examples of challenging meat applications are:

• Spiced and salted processed products
• Deli-style layered slices
• Sausages
• Moist or bloody whole muscle cuts
• Ready to eat meals containing meat

Here are examples of five product types, with the ideal frequency ranges used to find Fe and non-Fe physical contaminants using a 350x150 mm aperture size.

Beef and pork often arrive at processing facilities in slabs: large, frozen, uneven chunks. Large-aperture metal detectors make a great first line of defense for coarse inspection and are commonly used. A challenge with this approach, however, is that the incoming slabs may not be consistently frozen before inspection, which can change the product effect seen by the metal detector; thus, the technology used must be able to accept multiple products at various temperatures both clean and with the target contaminants, and able to adapt to the variability.

With some metal detector technology, an oblong contaminant must have a specific orientation to be detected when passing through the metal detector. Depending on how the metal detector is configured, horizontal, vertical, or diagonal contaminant orientation could go undetected. And in a fast-running food plant, there’s no predicting how a piece of wire or shaving will land in a product.  However, a food metal detector that utilizes Multiscan technology can detect not only find smaller contaminants, but contaminants in the most challenging orientations. It is like having several metal detectors in one, which gives food processors the highest probability of finding ferrous, non-ferrous, and stainless-steel metal contaminants.

Washdown requirements in the meat industry can be very demanding. The USDA calls for sanitation standards that can include high-temperature and pressure spray-down and use of caustic cleaners. Many metal detectors today are built to the IP69K rating (80˚C water at up to 1450 PSI), but this alone does not provide long-term defense from water intrusion into the metal detector case. In a typical meat processing plant, the equipment is used at a 40˚C ambient temperature but may be cleaned, sometime several times a day, using 80˚C water. Such thermal shock cycling can cause cracks in the seal between the epoxy aperture and metal case such that water can leak into the detection coils. The result is a permanent imbalance that only an expensive factory repair can address and it is typically required every few years.

Make sure your equipment has been tested and can survive up to 10,000 thermal shocks with no degradation in performance, has a soft epoxy fill and liner resistant to separation from the metal case, has welded aperture flanges to reinforce the liner seams, and is made of anti-corrosive 316 stainless steel (medical grade). This ensures that it cannot rust if harsh cleaning chemicals are not 100% removed during rinsing.

Not all contaminants found in the meat processing environment are metallic. Sometimes bones, stones, plastics and even glass can be present. In these cases, the foreign objects will pass through a metal detector undetected because the contaminants are not metallic. X-ray inspection is therefore the only possible option for foreign object detection.