Inspection and Sorting / Food Safety

How In-Line Inspection Systems Multitask

The right in-line inspection system can look for contaminants, check for weight and gauge fat content – all at the same time.

By Pan Demetrakakes, Senior Editor

Like a lot of things, and people, in the food industry, inspection systems are more valuable when they multitask.

Getting in-line inspection systems that can perform more than one function at a time can save money and space, as well as generally make things easier. Systems are available that can check for contaminants and for proper package weight at the same time – and in some cases, perform other functions.

Units that combine contamination detection and weight checking usually perform the two functions with separate machines that are integrated to varying degrees at points such as infeed and exit conveyors and within control panels and control software. For instance, with the CM33 CombiChecker from Mettler-Toledo, the checkweigher’s control panel is used to set up and configure the metal detector as well as the checkweigher. That allows both machines to adapt to stored product parameters every time a different product or package runs on the system.

The CM33 can bring together any of a range of options among Mettler-Toledo’s lineup of both metal detectors and checkweighers. Users can also choose from a variety of ancillary hardware like conveyors, guide rails, transfer plates, dual locking reject bins and rejectors, along with software options that include line integration, production monitoring and control, and communication options.

When specialty confectionery manufacturer Lake Champlain Chocolates added a new chocolate bar production line, it installed a combination metal detector and checkweigher from Mettler-Toledo. Plant operations manager Jason Antkowiak noted that the system “has a smaller footprint and was more cost-effective than buying two separate systems” – important considerations at Lake Champlain Chocolates, where both budgets and space are tight.

Loma Systems offers two kinds of combination systems: a Metal Detector Combination System, which combines a checkweigher with a metal detector, and the X5c & CW3 Check & Detect Combination System, which pairs a checkweigher with an X-ray system. Also available is the X5 Spacesaver/CW3 Check & Detect Combination System, for users who need even more space savings than an ordinary combo system can offer. All of Loma’s combo systems use linked color touchscreens with icon-driven menus for easy operation with integrated machine communication.

Like many combo systems, Loma’s use separate reject mechanisms – one for packages that are off target weight and one for contaminated products. This may take up a little more space than a single rejector would, but there are sound reasons for having two of them, says Kathryn Bors, Loma’s North American brand manager.

Having separate rejectors that push bad packages into separate bins, “helps with tracking and reporting, as well as meeting certain standards,” Bors says. “For instance, customers may rework incorrect weight products, but for food-safety issues they may take [contaminated] products to analyze or discard.”

Twice as nice

On the other hand, some suppliers market X-ray systems that are truly dual-function: Instead of linking two machines, they can detect contaminants and check weight, or perform other tasks, all in one machine.

Eagle Inspection Systems markets X-ray machines that can calculate a package’s weight by gauging the mass and density of the food inside with product-specific algorithms. Kyle Thomas, strategic business unit manager, points out this has an additional advantage in multicomponent products like meal kits. Checking weight with an X-ray allows the system to verify the weight of each individual component – something that wouldn’t be possible with the loadcells used by checkweighers.

Thomas notes that using X-rays for weight verification wouldn’t be feasible in countries where checkweighers are legal for trade – in other words, where the weight marked on the package can legally be verified in-line. Weights determined by X-ray wouldn’t meet those regulations, because a gravity-based method is required. Such is not the case in the U.S., he notes, where legal-for-trade weight is verified by random package sampling, not in-line methods. That relegates in-line weighing to quality control, which can be accomplished by X-rays just as well as by checkweighing.

Eagle systems also can perform other functions while they look for contaminants. One of them is looking for nothing – literally.

Some products, like baked goods and certain kinds of cheeses, are liable to develop internal voids due to air pockets forming during processing. These are hidden until a consumer cuts into the product and discovers them.

“In bread and cheese and things like that, it might be looking for voids within the product itself,” Thomas says. “If it doesn’t fully form, you get an air pocket or a void, leading to a product that may look good on the outside, but once you cut it open, you’ve got a large air void. That leads to a customer not being satisfied with the product.”

Another dual function is fat analysis for meat products. Eagle X-ray systems can check the fat content of products like ground meat or the trim used to make it. This becomes important because most ground meat is graded and sold according to its lean content.

“Customers have struggled with how to ensure they are producing to a lean point, whether you’re a slaughterhouse providing trim to a processor or a processor that is taking that trim and turning it into hamburger,” Thomas says. “They want to only give the customer what they paid for – no more, no less.”

Eagle’s X-ray systems can detect fat content from more than 30 tons of product per hour, Thomas says. It operates through dual-energy operation. The product is scanned twice, by X-rays at two levels of intensity. The contrast in values from both energy levels determine the product’s lean value.

True to itself

Dual-energy operation also can help X-ray systems in another vital aspect of performance: cutting down on false rejects. A system that keeps kicking out good product will be a drag on productivity.

Anritsu recently developed a dual energy sensor for some of its X-ray systems that minimizes false rejects while enabling more dependable detection of hard-to-find contaminants like thin, low-density bones. This is especially important for products like broiler chickens, which are bred for rapid growth and therefore tend to have a lower ratio of bone to meat mass.

The Anritsu DualX X-ray inspection system generates two separate images, at the high- and low-energy levels, that highlight contaminants better than a single image can. An analysis system, QUICCA3, uses a sophisticated algorithm to contrast the images and isolate the contaminants.

QUICCA3 automatically saves each X-ray transmission image for complete product traceability. The automatic extraction function allows a processor to check X-ray images of products before and after the defective product on the screen, which helps find problems before they occur.

Multi-level scanning also is used in metal detection, but for a different reason. Historically, products with high contents of moisture, salt or acid were hard or impossible for metal detectors to process, because the product would generate a signal in the detector’s electromagnetic field similar to a contaminant. By generating fields with more than one frequency of electricity simultaneously, a metal detector can compensate for this “product effect.”

Thermo Fisher Scientific also has the Sentinel, which uses multiple scan frequencies to increase the probability of finding all random sizes, shapes and types of embedded metal foreign objects.

Which way to X-ray?

Many processors are in situations where either X-ray or metal detection would be viable choices. Each has its advantages, but at the most basic level, the decision comes down to cost vs. versatility. X-ray systems are significantly more expensive, but they can find all kinds of contaminants; less-expensive metal detectors are limited to locating metal.

Just last month, Tyson Foods responded to one of the biggest recalls in its history by switching from metal detection to X-ray in the plant where the contamination occurred. Consumers reported finding pieces of metal in frozen chicken strips this spring, prompting a recall in late March that eventually totaled 11.8 million lbs. In early May, Tyson announced it was installing “metal-detecting X-ray machinery” to replace metal detectors at the plant in question, which it did not identify.

An interesting answer to the limitations of metal detectors is available from Eriez, which offers metal detectors and other equipment. Eriez markets PolyMag, an additive that makes plastic or rubber fragments show up on metal detectors.

“We are selling PolyMag to the manufacturers of plastic and rubber parts, tools, etc., which are used in food processing plants and where the risk exists for pieces of the parts to contaminate the food product,” says Jeff Kaveney, Eriez’ director of sales and product management. PolyMag can be used in everything from brooms and dustpans to machinery moldings; processors can look for it in parts and tools, or even specify it from their suppliers if they are in a position to do so.

As in many kinds of equipment, versatility is now available in in-line inspection systems to an unprecedented degree. Taking full advantage of the range of options this presents has the potential to save both time and money.