Metal inspection for fruits with high water content

Metal detection in moist products is often difficult. When inspecting raw products on arrival, the confectionery manufacturer Zentis uses a special metal detection system from Mettler-Toledo designed explicitly for inspecting conductive products.

In order to guarantee its products are of high quality, Zentis carries out a complete inspection of the raw products it receives before processing, to check for metal impurities. The challenge: Fruits with high water content are conductive and, therefore, cause similar signals during metal ­detection to those caused by metal contaminants. This so-called product effect can result in increased false ­rejections. However, with the Profile Advantage metal detection system from Mettler-Toledo it is possible to reduce the false rejection rate by up to 95%.

No chance for metal contaminants
Zentis uses the Profile Advantage to inspect pineapples that are then used to make fruit premixes. The diced pineapples arrive at the Zentis factory in Aachen in cans weighing between one and two kilograms. In order to check whether metal splinters have potentially made their way into the raw product, either because of friction caused by the supplier‘s slicing ­machines or during automatic can opening, the pineapple chunks are passed through the Profile Advantage metal detection system before further processing. This also prevents machines further down the production line being damaged by metal contaminants in the raw product.

Improved detection
During inspection the Profile Advantage records multiple signals on ­several frequencies simultaneously (multi-simultaneous frequency technology), and is thereby able to suppress the product effect. During ongoing production, this process is repeated for the content of every can in a fraction of a second.
Many other metal detection systems simply compare the current ­signal with the signal recorded during calibration. Detection sensitivity is, therefore, up to 50 per cent higher for fruits with high moisture content when using the Profile Advantage, compared to conventional metal­ ­detection systems.

Increased system availability
The lower number of false rejections results in noticeable cost reductions during daily use. The Profile Advantage‘s high system availability also contributes to reducing costs. This is the result of an early warning system that sounds an alarm as soon as detection performance deviates from the fixed standard, and not only when an error is eventually detected.
This reduces the number of daily performance tests, meaning production managers are able to plan ­machine downtime better. The Profile Advantage‘s clustering technology has a positive influence on system availability as well. This technology enables the inspection of several products using only one product setting. Thanks to this improved operation, employees benefit from reduced setup time when changing products.

Conclusion
By using the Profile Advantage metal detection system, Zentis has been able to make production more cost-efficient while simultaneously maximizing product safety. The Mettler-Toledo system thus plays an important role in increasing the competitiveness of the long-established company.