A tweak of a test discovered by a University of Missouri researcher could keep contaminated eggs off store shelves.
PCR-based testing for salmonella has been around for years, but it couldn’t be trusted, because it couldn’t differentiate between live and dead salmonella cells and only live cells cause sickness.
University of Missouri food safety researcher Azlin Mustapha modified the PCR test. She injected a dye into the test sample. Dead cells absorb the dye. The test only reads the live cells.
“The only difference between those currently available methods and ours is the fact that ours helps to differentiate between the live and dead cells,” Mustapha says.
That makes all the difference. The PCR tests can be ready in 5-to-12 hours. The most popular tests for salmonella can take up to five days to produce results.
“That’s a long time for the food industry to be waiting around for results,” says Mustapha. “PCR-based methods can get you the results within a day or less.”
A test that fast would allow food companies to discover contamination earlier, preventing the shipment of contaminated poultry or eggs. An outbreak of salmonella caused by infected eggs caused thousands of illness and sparked a massive, costly recall. The new test could have prevented the contaminated eggs from being shipped to stores.
Salmonella is the most common cause of food poisoning in the United States, according to the Centers for Disease Control. The illness caused by salmonella can cause diarrhea, vomiting, fever and stomach cramps. Mustapha says salmonella testing in poultry is important because it persists in birds’ spleens and reproductive tracts. An infected bird passes the infection on to all of its eggs.
Mustapha worked with Luxin Wang, a graduate student in the food science program. Their research results were published recently in the Journal of Food Science.