Food Engineering
Engineering R&D

Two-trick pony

January 7, 2013
system schematic xray absorptiometry tech
An enhanced X-ray system moves the technology beyond contaminant inspection to precise analysis of the fat and lean components of meat.
X-ray inspection of food is gradually moving into the mainstream, going beyond the capabilities of metal detectors to add safety assurance against nonmetallic contaminants. Leveraging the technology’s capabilities to help rationalize higher costs could accelerate adoption. One additional application is chemical lean analysis of beef trim.
While a number of ways to calculate fat content exist, most involve sampling and bench top analysis. Even when skilled technicians are involved, sampling is prone to error and exposes buyers and sellers to financial penalties. Dual energy X-ray absorptiometry (DEXA) is a technology that can calculate in real time chemical lean ratios within 1 percent either in 60-lb. boxes or 2,000-lb. totes. DEXA relies on two arrays of response diodes, one operating at 70 kiloelectron volt (keV) to respond to the lower-energy spectrum and the other at 140 keV to respond to the high-energy spectrum. Advanced algorithms use the two resulting 2D images to precisely calculate content.
Directing the fat analysis program at Eagle Product Inspection is Richard Hebel, product manager-FA. A Chicago native, Hebel earned a bachelor’s degree in physiological psychology from Northern Illinois University in DeKalb, and a master’s from Cardinal Stritch University in Milwaukee. He joined Eagle in December 2011.
FE: How does DEXA differ from conventional X-ray inspection?
Hebel: The big difference with DEXA is that it uses two different X-rays and two different signals. For every point in the image, you’re actually getting absorbance information from two different spectra, which proves very helpful when calculating the fat-to-lean ratio of meat.
The EAGLE FA 720 system’s footprint is pretty much the same as that of inspection X-rays, whether cartons or bulk product in totes are being analyzed. Overall, it’s about six-ft. long, four-ft. wide and seven- to eight-ft. tall. It’s an industrially hardened version of the commercial units used in airports, and it’s rated IP 69K. You can open up the system and hit it with high-pressure water and caustics without a problem. Its operating range is 32°F to 70°F.
FE: Several inline analytics have been applied to fat analysis, including guided microwave spectroscopy (GMS). What advantage does DEXA provide?
Hebel: GMS only works with pumpable products, primarily dairy and peanut butter. DEXA relies on X-ray, while GMS is based on radio frequency and the way different materials absorb electromagnetic radiation. I’m not an expert on GMS, but I suspect it would do a good job with meat—provided the temperature of the meat is stable and consistent. With DEXA, it doesn’t matter if the meat is chilled, frozen or hot.
Beef trim can arrive at a grinding operation frozen, refrigerated or hot. Grinders are pushing their trim suppliers to meet a chemical lean content that is dead on. They want trim that is within 1 percent of chemical lean spec so they don’t have to rework the meat later.
GMS is more likely to be applied where meat exits a grinder, whereas DEXA is likely to be used before it reaches the grinder. GMS instrumentation at the output of the grinder head would validate the lean content, but if it’s out of spec, the likelihood of overworking the meat exists. Downstream process analytics like GMS are complementary technologies. The more instrumented the process lines become, the better for all technology providers.
FE: Is X-ray for chemical-lean analysis a niche application?
Hebel: Trim can constitute up to 40 percent of the cow, so the market potential is huge. A small slaughter operation might process the whole carcass, but a global supply chain has evolved for most of the material, and there are distinctions beyond chemical lean for trim from different regions. For example, grain-fed beef from the US is fatter than grass-fed meat from Australia and Brazil, and fast food operators in the United States have begun specifying different blends of grass-fed and grain-fed trim. As a consequence, grinders are tightening their suppliers’ specs and increasing their fat claims for trim that doesn’t meet them.
FE: Are fat claims a major driver in implementation?
Hebel: Fat claims have become a contentious issue. Both sides have gamed the system for years.
Many grinders use sampling techniques that are subject to error to determine the lean ratio of trim that arrives in boxes or combos. If the samples suggest there is too much fat, they will assess a fine or penalty against the supplier. Until now, there was no way for a slaughter house to dispute those claims. This technology gives them a way by providing a full record to support what they shipped.
FE: How does the technology account for moisture?
Hebel: Almost all the moisture in trim is in the lean portion, which is a matrix of protein and moisture. Hot boning is the most common way of generating trim. The process time from slaughter to our system is remarkably consistent in that case, so if you calibrate the system to that process, there is no measurable effect in the analysis because of moisture. However, if you are dealing with a liquid, such as fluid milk, more variation would be evident.
FE: What foods are appropriate for DEXA?
Hebel: The overwhelming applications are for red meat—lamb, goat, cattle. It could be extended to turkey and poultry, but we really focus on red meat, specifically raw meat. When you’re dealing with cooked meat, usually there are added ingredients, particularly salt, which can mess up X-ray readings. Additionally, the volume being inspected is considerably smaller.
FE: Ground beef sold at retail now is required to disclose its fat content on the label. Is that increasing the adoption of fat analysis?
Hebel: Major retail chains are considerably more aggressive in their demands on suppliers to accurately disclose fat content; some also demand X-ray inspection. That causes a ripple effect through the supply chain.
Five or 10 years ago, there really wasn’t a highly accurate method of measuring lean. Ground beef sold as 85 percent lean relied on visual measurement, which was maybe within 5 percent plus or minus, depending on the skill of the person making the judgment. US commodities are still based on visual lean. A significant part of the value of this technology is its ability to limit either overpacking fat and getting returns or overpacking lean and giving away value.
FE: Is USDA exerting pressure for more precise lean labeling at retail?
Hebel: The department doesn’t speak definitively about this. Visual lean has been a rule of thumb practice for 100 years. USDA will never require processors to use a particular technology to measure a given constituent. Still, new technologies like DEXA will be cited under minimum diligence of trade requirements. More importantly, precise measurement results in more value, and the earlier in the process that it is done, the more likely value will be realized downstream.
FE: Why was validation of DEXA done in New Zealand?
Hebel: Our roots are in New Zealand and Australia. Eagle is a spinoff from Smiths Heiman Detection. The EAGLE FA 720 is adapted from Smiths’ security system used in airports. Meat is a significant part of the economy in that region, and university research tends to be directed toward maintaining those exports. From a technology standpoint, the meat industry there is probably the most advanced in the world.
The government commissioned an evaluation of DEXA by one of New Zealand’s largest meat companies; GNS Science, specialists in geological research and nuclear science; and the Institute of Food, Nutrition and Human Health at New Zealand’s Massey University. The technology received the stamp of approval for lean analysis, as well as contaminant detection. In the near term, the major advantage is the ability to capture images of contaminants, particularly bone, and store them for track and trace. That is valuable for purposes of tracing back any problems.
FE: Is the technology used to any extent in North America?
Hebel: Meat is a conservative, incredibly labor-intense industry that has used some of the same methods for more than 100 years. Companies are watching what technologies are being adopted downstream by major processors of premium sausage and other products. DEXA is being deployed by progressive trim suppliers and grinders.