Five New Technologies for Inspection

May 6, 2013
Lab testing will always be the gold standard in food inspection, but rising throughput rates are leading to more quality assurance at the point of production.

Quality is assured by the tools of inspection, and food and beverage manufacturers are beneficiaries of a steady progression to bring inspection closer to the point of production.

Hyperspectral imaging can flag cut potatoes with sugar-deprived ends that will turn black when fried. Key Technology is integrating hyperspectral systems into sortation equipment to remove those cuts before they become fries.

In-line and at-line inspection is a long-running objective in food processing, although higher throughput rates have turned it into more of an imperative than a goal. As production speeds ramp up, lab testing looks more and more like a luxury the industry can ill afford. The rework and scrap created by the time that lab samples flag a problem are a serious drag on optimized production.

Sophisticated rotational viscometers for rheological and texture measurements are built by Brookfield Engineering Laboratories Inc., in Middleboro, Mass. They provide important quality data for both Newtonian and non-Newtonian fluids, the latter of which includes most foods. For example, makers of salad dressings must be mindful of yield stress, the force needed to get the dressing to flow out of a bottle. Quality control must monitor the stress level to avoid producing dressing that either gushes out or refuses to flow.

Robert McGregor, Brookfield's general manager of global marketing and high-end instrument sales, characterizes the firm's benchtop devices as "relatively inexpensive," despite features like an on-board smart phone that "can send messages and tell you when you're out of spec." Identifying the problem with an in-line test would be even better, and the inspection tools for that exist. The cost, however, is multiples higher, "and you need a person to be a champion to promote in-line testing," he observes.

The density of semi-solids such as shortening is a quality spec that can be tested at the line instead of the lab with the consistometer developed by Innoquest Inc.

"Computerized benchtop equipment is great for the Rand D lab," allows Bill Hughes, an engineer and founder of Innoquest Inc., Woodstock, Ill., but the time lag between the lab and the loading dock can be too great. Five years ago, he developed a handheld device to quantify the consistency of semi-solid foods that require a quantitative test before they ship. He dubbed it the SpotOn consistometer.

The tool was developed specifically for vegetable shortening and margarine manufactured by Bunge North America, which had exclusive rights to Hughes' consistometer until last year. The device combines manual force with on-board diagnostics: The user plunges a rod into the food material, and the device measures penetration resistance and correlates it with depth and temperature. An infrared depth sensor calculates the probe's speed of penetration, and if the user exerts too much or too little force, a measurement is not recorded. Typically, an operator masters the proper force after five probes, according to Hughes.

Kevin Higgins is the Managing Editor of Food Processing Magazine. You can email him at [email protected] or check out his .

Measures of consistency, temperature and depth are displayed on an LED panel connected to the device's microprocessor. Data are recorded and downloadable.

Metal detectors are the most common in-line inspection devices in food plants, and the technology is getting better, with fewer false positives and superior detection capabilities.

Edible oils and margarine are placed in a hardening room after processing, and when consistency is in spec, pallets are released. Sometimes, there will be an area on the pallet where product is out of spec. Testing with a consistometer identifies where that area is and allows processors to optimize storage time. Ice cream, whipped toppings and specialty dough are among the semi-hard foods Hughes believes could benefit from his inspection tool.

Double-duty inspection

While quality data are essential for process control, inspection hardware often is viewed as a risk-management tool against negative outcomes. When inspection is combined with a value-added function, capital costs are easier to justify. One example is the BioPrint system that Key Technology Inc., Walla, Walla, Wash., recently added to its portfolio.

Key acquired erstwhile competitor Visys NV in February, complementing Key’s belt-fed sorters with the Belgian firm's chute-fed in-air sorters. More importantly, Key acquired advanced laser technology and hyperspectral-based BioPrint capabilities for its technology tool kit. Visys's Cayman chute has a concave shape that turns "a free fall into a controlled fall," explains John Kadinger, Key's marketing manager. By positioning ejector valves closer to the product passing through the chute, there are fewer false rejects, which means yield is increased.

The chute was an instant hit in California nut harvesting, Kadinger says. Shells, stones and other debris can account for as much as a quarter of walnuts fed into the system, and the chute achieves about a 98 percent efficiency rate in removing the debris. By combining the chute with Key's own three-way sorter, Kadinger predicts efficiencies will approach 100 percent, and value will be added. Whole nuts will be separated from pieces, then multiple data points will segregate the lightest colored, most valuable nuts in a single pass.

Hyperspectral's inspection potential goes beyond walnuts, however. The technology and supporting algorithms develop a biological fingerprint of the food being sorted. Defects that are undetectable with cameras are exposed. For example, a potato reacts to stress by withdrawing sugars from its extremities, resulting in dark splotches called sugar-ends in French fries and zebra chips in potato chips. If those defective fries and chips are removed upstream before value is added, yield and productivity are increased. Extensive testing has demonstrated the technology is effective. The challenge now is making it affordable.

“It’s driven by the market and whether the cost can be justified,” says Kadinger. “We believe it is a valuable improvement.”

Dual energy X-ray absorptiometry (DEXA) is an innovation that is further along the commercialization curve. DEXA uses two arrays of response diodes operating at two voltages to generate two 2D images of the product being inspected. When applied to beef trim, DEXA not only screens for bone and other contaminants, it calculates chemical lean content within 1 percent.

Conventional inspection relies on human judgment, “which is maybe within 5 percent, plus or minus,” notes Richard Hebel, product manager-FA at Eagle Product Inspection, Tampa, Fla., which is now a part of Mettler Toledo. “Trim can constitute up to 40 percent of the cow, so the market potential for DEXA is huge.”

DEXA units are being used in Australia, Latin America, the U.S. and Europe, “and we just installed our first unit in China,” he adds. Most domestic trim suppliers still rely on visual lean, but grinders are levying fines on suppliers who deliver out-of-spec trim, and that will drive greater adoption of DEXA, Hebel predicts.

The upside of IEDs

U.S. military superiority quickly overwhelmed local forces in Afghanistan and Iraq, but snuffing out guerilla resistance on both fronts proved much more difficult. Improvised explosive devices using trace amounts of metal caused many U.S. casualties. Better metal detectors were necessary to protect the troops, and that drove technical advancements that now are incorporated into the detectors used in food inspections.

Multi-frequency detectors exemplify this, measuring the strength and direction of multiple magnetic fields before focusing on one. The Italian firm CEIA has taken this one step farther with multi-spectrum technology that simultaneously and continuously monitors multiple frequencies. This advanced system detects both magnetic and non-magnetic metals, including stainless steel. An industrial version was introduced in 2009, and Hayward, Calif.-based Heat and Control Inc. began sales and support efforts for CEIA's unit in North America the following year.

Products with high salt or moisture content, such as cheese, frozen foods and nonhomogenous products, are a challenge for single- and multi-frequency detectors because the controls must mask the signal generated by the product being inspected, explains Todd Grube, Heat and Control's inspection product manager. With a multi-spectrum system, not only does the unit do "a much better job of masking" the product signal, it is able to generate qualitative data.

For example, temperature changes in product on a frozen line can be monitored over time; if the temperature drifts upward, the strength of the product signals will change. "If the data were tied to a plant network, it's not unrealistic to poll the detector and alert personnel before product quality is affected," says Grube.

Subpart E of the good manufacturing practices section of the Code of Federal Regulations governing food production specifies that processors "protect against the inclusion of metal or other extraneous material in food." That helps explain the presence of metal detectors in most production facilities. But when inspection tools can perform multiple functions to ensure product quality, the demands of high-volume throughput also are served, and value is added.

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