[Food Safety] Foreign Object Detection

Analyzing your product and process for the most appropriate types of equipment; placing equipment upstream; and ensuring that equipment is always in peak working condition are three of the top recommendations manufacturers/distributors make for best practices in foreign object detection.

"I have been in the metal detection, foreign-object detection business for over 20 years, and never has there been a greater emphasis placed on product safety and contaminant inspection," says Mark D’Onofrio, vice president and general manager for Lock Inspection Systems Inc., Fitchburg, Mass. "Metal detectors have been used in these industries over the past 40 years, but the emphasis placed on how they should be used has changed."

ANALYSIS. A common misperception, says Dave Heubel, Sanitary Market Manager for Eriez Magnetics, Erie, Pa., is that a plant needs only one technology. Whether the plant believes that metal detectors can do it all, or that it regards x-ray technology as a silver bullet, as Oscar Jeter, national sales manager for Mettler Toledo Safeline, Tampa, Fla., says some plants seem to think, most production processes need more than one type of foreign object detector at various points in the process.

"Metal detectors are very dependable and very accurate at what they do. But all they do is detect metal contamination," Jeter says. If all you have need of is metal detection, use that; but most plants will need to supplement metal detection equipment.

The use of a magnetic separator followed by a metal detector can be beneficial, Heubel says, as the magnets can detect and separate smaller pieces of metal while the detector can pick up both ferrous and non-ferrous metals. X-ray equipment can then be valuable for detecting rocks, glass and other non-metal objects; as well as recognizing correct shape and providing product weight confirmation.

But it is the technological advances and automation of the last year or so that are making x-ray more and more common in food plants. In the past, said Wyeth Thomas, Safeline x-ray salesman, "X-ray was always used by more of an engineering type person. Now [a system] can be set up by a complete novice within five minutes." The systems are now very intuitive, he says. "You basically need to know zero about x-ray."

The machines are also safe for use, he says. Most are built to European standards which are five times stricter than those of the U.S. "The x-ray machine doesn’t contain a radiation source. It’s an electrically generated x-ray source." This means it is turned off immediately when the electrical supply is turned off, there is no residual radiation. In addition, Jeter explains, pharmaceutical companies have done product-study tests on the x-ray detectors, running products through the machines hundreds of times, resulting in "no discernible change" to any product.

However, Jeter cautions, x-ray machines are not silver bullets that can detect everything. They can not, for example, detect wood. X-ray works on density, and although wood is very hard, it is not dense. "If it will float on water," he says, "it may not be x-rayable."

The best way for a plant to determine the types and number of detectors or separators needed is to work with suppliers on a plant and process analysis; to survey the plant, walk the process, assess the HACCP plan, address history, then make equipment recommendations. "One of the biggest things I see is that today people think they can get everything off the Internet," Heubel says. "Customers don’t want to talk to salespeople." This is a mistake, he explains, because today’s salespeople are very technical and work with the equipment and processors daily; so they have the experience and knowledge to help plants make good decisions. "There is always a reluctance (to interact with salespeople)," he says. "People want to do their own research, foregoing an excellent resource [in the salesperson]. There is no substitute for actual experience."

Some plant managers will call a supplier sure that they know exactly what they need, believing that an x-ray machine or metal detector is an obvious choice, Jeter says. "But when they dig deeper, they may find that they need both." In fact, he adds, most of their clients do incorporate both technologies into their process. "X-ray is relatively new, but many are looking at it not as a replacement to metal detectors but in addition to."

This is because the two technologies work well hand-in-hand to keep a product safe. Although x-ray technology will find objects which cannot be detected with the metal detector, it is not as good at detecting low-level metals, such as aluminum or a foil chewing gum wrapper – both of which the metal detector will pick up.

UPSTREAM PLACEMENT. "It’s easier to remove one bolt than 5,000 pieces of the same bolt that’s been ground up," says Dave Heubel, sanitary market manager for Eriez, headquartered in Erie, Pa. Not only does this placement prevent additional contamination by early detection, Heubel says, because the metal can damage your production equipment, the sooner an object is detected, the less costly a single bolt or metal fragment could be. "What about all the stuff that the metal does on its way downstream?" Heubel asks. "Think of metal as a contaminate; it really is a hazard."

In addition, if a processor places its only metal detector or x-ray machine at the end of its line, for detection of foreign objects in packaged product, each rejected package represents a full processing investment which may have been avoided by placing the equipment further up-line, he explains. This is particularly true if the metal was brought in from the farm or a supplier. While this final packaging-point detector can be a critical control point, important for detecting such things as in-process metal contamination caused by machinery wear, rarely is it a good practice to make it the only such control.

It is for this same reason that Jeter recommends that metal detectors be installed at numerous points of a process and that every plant have good general practices, such as cleanliness and hygiene, jewelry restriction, gum-chewing bans, etc. "It goes back to the basics," he says, "good plant sanitation and hygiene, and the control of substances that can be a problem."

KEEP IT WORKING. "Too often companies install metal detectors and assume that they are covered from a liability standpoint," D’Onofrio says. But if a plant does receive consumer complaints of a foreign object in the product, the processor must ask a number of questions of itself in relation to the time that the reported contamination would have occurred, such as:

* Were the units powered on?

* Were the metal detectors
operating at the proper sensitivity levels?

* How often are they checked?

* Is there proof the detectors were checked?

Such questions can be answered through proper installation of equipment and any related software or other technology, as well as ongoing equipment maintenance and:

* shift performance checks

* constant reporting of equipment
status

* verification of performance

* logging of detection events.

In addition, Jeter says, whenever a detector does reject a product or ingredient, steps need to be taken for identification. "When equipment rejects stuff, it’s very important to find out what the object was that caused the rejection and how it got there." Is there broken machinery? Did it come in with the raw ingredient? Was something dropped by an employee?

When plant management is determining it needs for foreign-object-detection equipment, it should never think of the equipment as a silver bullet. "There are some types of contaminants that are very difficult to detect once it is mixed into the food," Jeter says. Taking, for example, undetected wood that is ground into sausage. "There isn’t any equipment at this point that will detect that."

For this reason, a plant’s food-safety program which includes such things as visual inspection, strict controls on wooden pallets, etc. are critical to the integrity of products. "If I could recommend one thing above all, it’s additional training," Jeter says. "That’s what builds a strong quality assurance program." Not just for the QA manager, but training to ensure all employees understand the equipment, its programming and its limitations.

"Everything has its limitations," he says. "Our equipment is just one part of your detection program. It’s a tool to work hand in hand with your quality assurance program; and the program is most important." QA

The author is staff editor for QA magazine. She can be reached at llupo@gie.net.