Virtually eliminate false rejects from your production line

Challenging food products such as those with high salt or moisture content, variable temperature, or packed in metalized film can result in ‘good’ product being falsely rejected when inspected for metal contamination; this often results in lost time and wasted money. The false rejects are due to a phenomenon called ‘product effect’, where these product characteristics create an electrical signal that can cause unwanted false readings when using a metal detector on a production line.

Whilst some food processors reduce the metal detector frequency to allow variable products to pass through undetected, this increases the risk of smaller metal contaminants going undetected in a product. Fortunately, Mettler-Toledo’s Profile Advantage metal detector uses innovative technology to overcome product effect to virtually eliminate false rejects, without compromising sensitivity levels, detecting significantly smaller irregular-shaped metal contaminants.

What is ‘product effect’?
Product effect is used to describe instances where a product’s own characteristics affect the metal detector in the same way as a metal contaminant. It’s not just metal that has the ability to generate magnetic fields and conduct electricity. Food can do this too, although to a lesser extent than metal itself. Salty products can conduct electricity and form eddy currents if subjected to magnetic fields, causing the product to form a magnetic field of its own. Although salt has low permeability, if the product is large enough, it would still create a magnetic field of sufficient size to affect the metal detector in the same way as a metal contaminant.

Foods with high moisture content, such as fish, poultry and fresh meat, are often referred to as ‘wet’ products. These items are reasonably good conductors and are more likely to produce a signal within the metal detector that’s similar to that of a metal contaminant. This makes distinguishing product from metal contamination much harder. Moisture and salt content change from pack to pack and from animal to animal. Different cuts of beef, for example, could have different levels of moisture, further complicating matters.

By contrast, ‘dry’ products are less likely to cause substantial change in the magnetic field of the metal detector. An item such as flour, for example, won’t have a significant impact on the balance state of a metal detector due to its low conductivity and permeability. Additionally, some wet products exhibit nearly no product effect when in a frozen state.

How to combat product effect without compromising sensitivity
Modern metal detectors, such as Mettler-Toledo’s Profile Advantage, have been specifically designed to dramatically increase detection sensitivity for products that are difficult to inspect due to product effect.

Featuring Multi-Simultaneous Frequency (MSF) technology, these metal detectors use a combination of high and low frequencies, coupled with built-in Product Signal Suppression technology with two stages of discrimination, frequency and phase. By cancelling the information from the combinations of high and low frequencies, the technology removes the product signal, allowing much smaller contaminants to be detected.

MSF is also able to deal with product variations in a very effective manner. The software algorithms deal with variations in product effect for each product inspected. The result is up to fifty per cent improvements in metal detection spherical sensitivity levels, compared to traditional metal detectors, making it possible to detect significantly smaller irregularly-shaped metal contaminants. This protects manufacturers’ brands, and ultimately help protect the end consumer from harm.

Added benefit: False rejects are virtually eliminated

Overcoming product effect using Profile Advantage technology (rather than reducing metal detector sensitivity) delivers the added benefit of virtually eliminating false rejects. This means productivity is enhanced, the investigation and documentation burden on Quality staff is significantly reduced, and production output increases.

By conquering the product effect phenomenon, Profile Advantage metal detectors provide greater confidence that all products sent into the retail supply chain are free from even the smallest metal contaminants, increasing brand protection whilst simultaneously reducing costs and improving productivity.

Calculate your savings

Visit to use our new online ROI calculator to see how you could benefit from virtually eliminating false rejects by using Profile Advantage technology.

For more information on metal detection, visit