July 1, 2007
By Tom Wray, Associate Editor
The development of rapid testing methods has kept pace as an up-and-coming innovation in the fast-moving food-safety arena.
In an economy in which time is money, meat and poultry products need to be moved to the consumer quickly. Speed is even more important when those products need to come back because of contamination.
Thanks to advancements of the past 10 years, processors have the capability to test for a range of contamination quickly and, more importantly, accurately.
Daniel Y. C. Fung, a professor of food science at Kansas State University in Manhattan, Kan., says there many tests out in the market today, each with different capabilities. “There are a lot of diagnostic kits,” he explains. “There are some convenient diagnostic kits that have come out in the past 30 years.”
In fact, there are so many available, it is easier to categorize them by type than list them. The conventional rapid test kit is the most used, often in hospitals and the food industry. It is testing at its most basic, taking a sample and growing a culture from it.
From there, Fung explains, it gets more precise and complicated. There is now immunology testing that can identify the organism and pinpoint it. The newest is genetic testing.
“They are more precise in probing the gene of the organism,” Fung says.
Genetic tests use polymerase chain reaction (PCR) in its testing. “It’s a very powerful tool that you can actually get a culture and tell where the food contains the organism or not,” he continues.
He adds that a benefit of genetic tests is the speed. A result can be produced in four or five hours after culturing over night. Conventional testing can take up to three or four days. There are even some PCR tests that can give real-time answers.
These tests, which can include techniques such as micro array and biochips, are very precise methods that can identify the organism itself. The accuracy is vital. The sensitivity can be a drawback.
Fung says one important detail that needs to be accurate is whether the organism is alive or dead. He uses Salmonella as an example.
“If you take a chicken and cook it, you kill the salmonella. It’s safe to eat,” he explains. “But some of the systems can still find the DNA, even though it’s already dead.” At this point, the viable cell count is very important, which involves a range of tests, Fung says.
Purnendu Vasranda, a professor of food science at the University of Wisconsin-River Falls, says that false positives can be a drawback. “That will give you a signal when there is no toxin present,” he explains. Moving fast
The technology is advancing rapidly, says Fung. He uses Salmonella as an example.
“Ten years ago, it would take seven days to find out,” he says. “We have cut that down to about three days by five years ago and then down to two days. [It’s] now half a day in some of the systems. The whole field is moving along healthily.”
The benefits to rapid testing are obvious, Vasranda says.
“The benefits are the saving of time,” he states.“The other obvious is the electronic data handling and analysis. Not just the raw numbers, but what does it mean.”
That’s where accuracy comes in again. Vasranda says today’s equipment is sensitive enough not only detect E. coli, but whether it’s the dangerous O157:H7 strain or the more benign common strain.
Recent health scares and recall have raised the issue of rapid testing, according to Vasranda, making it ever more important in a world of just-in-time stocking and new concerns.
Speed becomes paramount when the testing itself is being done. “If something happens, we then have to find out what it is immediately,” says Fung. Otherwise, shipments that should be going to stores and restaurants will instead sit in refrigeration, costing both storage and lost sales. He offered the example of one company whose product was tested and contamination found, and the final cost to the company tallied $5 million.
Fung goes on to say that larger companies are investing in having microbiologists and a lab on site. Otherwise, a company must send samples out to be tested, which adds travel time to the wait for results.
Time is not only the factor of essence, however — steps such as these can be expensive, Vasranda says. For tests in which samples are sent to a lab, there is also a loss of flexibility.
A machine can’t stop a testing process if the something goes wrong or interview company floor employees to learn more about the specific situation.
However, processors dare not face the flip side in which a pathogen is not discovered in product before it heads out to market.
“If you look at things like avian flu, if you don’t have a proper test to do any of those things, then you can’t plan,” Vasranda says. “It all hinges on your ability to catch the culprit in a timely manner.”
Always a concern
For Fung, recent recalls have not made the issue more urgent — it already was.
“For microbiologists, we were already starting to be very concerned anyway,” he says. “[However,] it does highlight the need to test faster.”
The federal government is doing a good job in tracking problems and stopping contamination before it
causes illnesses, Fung says. Compared to much of the world, the American food supply is still the safest.
Part of the solution in protecting food, and easing the need for rapid testing of food, is basic education. Fung explains that basic food safety, which most companies already follow, must extend to the consumer and his or her handling procedures. Hot food must be kept hot — at temperatures 140 F or higher — and cold food kept cold — 40 F and below. That alone can do a lot to protect consumers.
“Leave [the food] out for three or four hours, and you may have a problem,” he said.
The field of rapid testing is growing as quickly as the need for them.
“This is an exciting field of analysis,” Vasranda says. “With the convergence of electronic, nanotech, and molecular biology, the future is going to be very exciting in this area.”
And it will keep growing. Fung says that this year 1.5 billion rapid tests will be done worldwide. That represents a market worth more than $5 billion.
Some work still needs to be done. Not just with the technology but also with synchronization between different countries. Each government has its own special concerns and standards. Vasranda says that more needs to be done to have countries work together and create a smooth system for testing as global trade grows.
The best thing processors can do to foster the development of this system is to educate. Both Fung and Vasranda say that keeping up to date on the newest developments is vital. Food safety is often a panel discussion topic at trade shows. The Food Safety Summit, held every year in March, covers topics such as these in depth. Also, Fung and Vasranda both host seminars on the need and techniques of food safety and testing. In fact, Fung recently completed his 27th such workshop. The methods are there for processors. It’s now time for processors to take rapid testing to the next step — any action along those lines is only bound to help the industry as a whole.
“There are more tools in the tool boxes than there were before,” says Vasranda. “It’s very exciting.”
Education on Rapid Testing
An opportunity to learn more about food safety is coming up in October.
The Food Microbiology Symposium will be held at the University of Wisconsin-River Falls from October 21 through 24, 2007.