Writer: Karl Hill
Standard methods for detecting disease-causing organisms in food can take days. Rapid screening would benefit consumers and producers - but not if accuracy is sacrificed for speed.
That's where the Food Safety Laboratory at New Mexico State University's Physical Science Laboratory comes in. The lab, funded by the U.S. Food and Drug Administration, tests procedures and develops standards for rapid testing of food products.
"The FDA's standard methods are highly accurate - they have to be," said Myles Culbertson, a PSL project manager who oversees the lab's operations. "But they are also relatively slow, typically, because it is relatively old technology."
The FDA, he said, "needs to know if new, faster technologies are as accurate as their own gold standard."
The lab has been getting good results with some new procedures, said Willis Fedio, the microbiologist who runs the lab.
"We are looking at some very rapid methods for detecting pathogens," Fedio said. "For instance, identifying salmonella in a food sample typically takes six to nine days now. Some of the methods we're working on take one day, and there are even more rapid methods for some organisms. Some DNA-based methods produce results in six or seven hours."
From a public health standpoint, the benefits of rapid identification of contaminated foods are obvious. From the producer's perspective, faster testing of a shipment that is not contaminated can mean the difference between getting a perishable product to market on time or not. "If a shipment of produce coming into New Mexico across the border has to sit for a long time, it's lost," Fedio said.
Initially the FDA considered the concept of on-site testing at border crossings, he said, "but the time it takes to transport a sample to a lab is not as significant as the time it takes to analyze the sample."
The lab's job is to validate rapid testing methods, identify ways they can be improved, develop protocols for testing, and otherwise advance the technologies for identifying pathogens in foods. "Sometimes we will take a method that was developed for one food and expand it to others," Fedio said.
A federal agriculture appropriations measure recently passed by Congress, and expected to be signed by the president, earmarks $2.35 million for PSL to continue its research and development work for the FDA.
In addition to the Food Safety Laboratory, the funding will support PSL's Counterterrorism Chemical Technologies Laboratory, established last year to develop and evaluate techniques for detecting toxins in food "which may or may not be intentionally placed," Culbertson said.
It is a challenging task, because "a particular toxin will show up differently in different foods," he said. "It will throw off a different 'signature.' It will look different in a grape than in a banana, and each combination needs to be identified."
Using mass spectroscopy and other techniques, the lab develops and validates methods for detecting those signatures, while avoiding false positives, said Omar Holguin, the chemist who heads the laboratory.
"Foods vary greatly and they have very complex matrices," Holguin said. "We may be able to extract 'Toxin A' very well from a plant-based food, but an animal product may present different challenges. We try to figure out the different conditions and make sure the FDA methods work well in any situation."
A third aspect of PSL's work for the FDA is development of a computerized risk-assessment system for identifying shipments of food entering the United States "that might need a closer look," Culbertson said.
"We are in the early stages of proving the concept and testing it in real-world situations," he said.
The system is designed to "absorb a tremendous amount of data - unrelated, disparate data about that shipment, that industry, that supply chain, regulatory information," Culbertson said. Using some of the principles of artificial intelligence, the system would order the information and assign a "risk score" to the food shipment, he said.
© 2013 New Mexico State University Board of Regents
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