Perhaps one of the most sensitive issues with inline safety involves whether to use metal detectors or X-ray systems.

Todd Grube, manager of inspection systems, Heat and Control, called X-ray systems the multi-tasker of the inspection world.

“In addition to detecting metal and materials such as plastic, stones and glass that are ‘invisible’ to metal detectors, X-rays can identify deformed, damaged and missing product,” he said. “To decide if an X-ray system or a metal detector is right for your operation, consider the size and type of contaminants that need to be detected. What type of packaging is used at this point of inspection? Metalized film, foil and metal ties on bread bags will severely limit the effectiveness, if not prevent the use altogether, of a metal detector.”

Small amounts of aluminum may present a different challenge for manufacturers.

“Generally, a properly equipped X-ray system will find smaller metal contaminants than a metal detector will,” he added. “However, aluminum has a very low density, which makes it harder for X-rays to detect compared with other metals. The high-conductivity properties of aluminum, though, may allow metal detectors more reliable detection than X-rays.”

Geri Foley, metal detection sales manager, Mettler Toledo, weighed in on the topic, suggesting that bakers first identify types of contamination they risk. Is metal the only type of foreign contaminant that may be present, or will there be glass or stone? If it’s only metal, she noted, then metal detection is a better solution. Otherwise, the X-ray would be better if the product is packaged in aluminum foil.

“A bakery whose packaging is foil may decide to place an X-ray system on the line for end-of-line inspection and a gravity-feed type of metal detector upstream for inspecting raw ingredients,” she said.

X-ray inspection systems also may identify packaging defects, said Kyle Thomas, strategic business unit manager, Eagle Product Inspection, Tampa, Fla.

“Aside from identifying contaminants in products, the technology can simultaneously check for component count, fill levels and open packaging,” he said.

Bakeries also need to keep in mind the nature and complexity of the product that they are inspecting.

“For example, a scone with fruit and nuts will need more sensitive X-ray technology to detect contaminants based on their density, than a plain sponge cake,” Mr. Thomas said.