Loma has various combination systems available, including this pairing of an X-ray and a checkweigher.
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.
