Detecting Foreign Matter

Advances in detection technologies are helping to make the food supply safer than ever. Plus, these machines can do other things, as well.

By Mike Pehanich, Plant Operations Editor

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I'm old enough to remember baking soda submarines (yes, mine finally arrived!) and have fond recollection of that mostly bygone era when you wanted to find a surprise in your cereal box. But in this era of food safety vigilance, keeping surprises out of our food is one of the industry's most sincere ambitions.

More often than not, the threat to food safety comes when some unwanted element -- whether it be fragment of metal or grain husk -- enters a food or its package. Devices that enable processors to detect unwanted elements at desirable production speeds are invaluable. They help to ensure product safety and quality and keep away the lawyers.

But safety and quality aren't the only drivers to improvements in detection technology. Maintaining uptime can have immense impact on the bottom line, and effective detection of foreign matter can maximize production time without sacrificing safety.

While metal detectors continue to do their jobs, other detection technologies that recognize non-metal particles increasingly are being worked into the processing line.

Ease of use and connectivity are other issues driving new technologies and improvements and configurations of existing equipment. Here's a look at some of the latest advances and refinements in the field.

Digital advantage

Metal detection is a mature technology. The current generation of equipment has come close to reaching maximum sensitivity and detection capability. Thus, most of the improvements have aimed at easier system operation. The shift to digital systems, however, has gone a long way to do just that.

"The [digital] unit doesn't need to be calibrated with each product that runs through the line," explains Kevin Jesch, product manager for Heat and Control (, Hayward, Calif., which markets CEIA metal detectors and Ishida X-ray devices. "You can use multiple frequencies. If the plant is running different products, you can accommodate each with a different frequency and easily change." Digital signals also help to avoid ambient interference from motors and other devices, Jesch notes.

Variable frequency operation offers distinct advantages over single or limited frequency detectors. Loma Products (, Carol Stream, Ill., has a range of metal detection systems called Loma IQ3 that can operate at frequencies between 40 and 900 KHz. The systems also can adjust to the proper operating frequency almost instantly with each product or set of conditions, eliminating the expense and time of engineer set-up or adjustment.

Making metal detectors more simple means making them more problem-free. Heat and Control's CEIA THS series metal detectors have been designed to withstand the rigors of washdown and tough sanitary practices. "We've had good success in poultry operations in particular," he says, underscoring the stringent sanitary practices in that food segment. "The systems resist water and chemicals, as well as high temperatures and high pressures."

Simplicity of design is a plus, too. Fortress Technology (, Scarborough, Ontario, claims to have only 50-60 percent of the parts of its competitors. Other advances in metal detectors have included tougher designs, able to resist damage due to vibration and thermal shock. Driving much of the improvement in both metal detection and X-ray detection systems has been the quest to make such systems easier to use.

"X-ray has come a long way. Today, you can learn to operate a machine in five minutes," says Oscar Jeter, national sales manager for Safeline (, Tampa, Fla., a unit of Mettler Toledo. "You can also set it up in five minutes. It gives the plant something it can easily use and get up and operating fast. If it's part of your HACCP [hazards and critical control points] plan, it is important to get it up and running quickly."

New features of Safeline's Powerphase Pro metal detector incorporate features sush as color touch control and icon identifiers aimed at easier use. "Everyone knows how to use an ATM machine," says Jeter. "By using icons, you can guide people in their use of the machines. It's the same with us. We can walk people through. You don't need a 'retraining' program every time you change employees." Uptime, Jeter emphasizes, is of paramount importance. Plants can't afford to have processing lines down, but they can't afford to run without the assurance and protection that sophisticated detection systems provide.

"A growing trend -- although it's not huge yet -- is Ethernet availability," says Heat and Control's Jesch. "As processors want to integrate more discrete equipment into the packaging line, they want to have this capability. Not many are ready for it yet from a control standpoint. It's being used more for data collection than interpretation so far."

Everyone wants connectivity today, Jeter emphasizes, underscoring the importance of safety data collection to HACCP programs. "Processors need to connect to a central data point where they can prove a detection system was turned on and operating during a production run; log and document the monitoring of product during production; and log and document rejects," he adds.

Two techs, twice safe

Unwanted materials such as wood, insects, certain plastics, pieces of conveyor belt remain difficult to detect with metal detectors and other detection technologies. This fact has expanded opportunities for X-ray and other types of vision systems. Experience in the positioning of systems also has added to their effectiveness.

Processors are using multiple detection systems -- and often multiple detection technologies. "Metal detectors find only metal, but X-ray systems find any kind of solid contaminant," adds Jeter. While metal detector refinement aims at detection of tinier metal particles, X-ray and other emerging technologies can single out glass, stone, bone and some other materials.

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