In an ideal world, perhaps all of our food would be screened for pathogens before we consume it. But in reality, such testing is expensive and time-consuming for companies.
Most producers do not have the capacity to test for pathogens themselves and must send samples out to a lab. Results can take 2 or more days to process. For companies selling fresh meat or produce with a limited shelf life, this delay can hinder their ability to get product out before it starts to expire.
But a detection technology being developed by nanoRETE, a Michigan-based company, in conjunction with Michigan State University, will allow producers to test their products themselves, and to do it in under an hour.
The system, called X-MARK, works by using a pathogen’s antibodies to draw it out of a food sample via magnetic pull. These separated particles are then put on a biochip, which is fed into the reader, where an electric current will recognize a pathogen based on the pattern of its electrical current.
“It’s simple!” explained Evangelyn Alocilja, who designed the system’s nanoparticles, in a phone interview. Alocilja is a professor of biosystems and agricultural engineering at MSU and chief scientific officer of nanoRETE.
For anyone daunted by the mechanics of how the system works, it’s practical application is as easy as 1, 2, 3. First, obtain a liquid sample. Juice and milk already qualify. For solid products such as fruit, swish the sample in a bag of distilled water and use the water as your sample. Next, add in the nanoparticle solution, one for each pathogen you want to detect. Finally, put the sample on a biosensor chip and insert it into the reader. Let sit for 40 minutes.
“It’s truly field-based,” says Alocilja. “It’s on-site detection.”
X-MARK is not the first detection technology to screen samples in realtime, but it is highly sensitive, detecting as few as 5 to 10 cells per milliliter as opposed to most technologies which have a threshold of 1,000 to 10,000 cells per ml. It’s also faster than most products on the market, and is expected to be affordable once it goes public. Production costs for each test are under $1 each.
“The problem right now is that tests are so expensive that producers don’t do a lot of testing,” says Alocilja.
The system will cut down on testing costs in the short-term, but it could have an even bigger cost-saving impact in the long term by preventing contaminated food from leaving the facility, helping prevent the loss of thousands and even millions of dollars in a recall or outbreak.
“Not only are there the costs of an outbreak or recall,” points out Alocilja, “but there is a negative impact on the brand.”
Indeed some recalls and outbreaks result in bankruptcy for the implicated company.
This does not mean that X-MARK will be a cure-all for outbreaks. Tests can only screen so many products, and a contaminated product may not be caught if it isn’t among the sampled product.
Also, increased testing should not be an indicator that it’s okay to slacken food safety controls earlier on in the production process.
“Testing doesn’t make it safe. All testing does is tell you that a process is under control,” explained Craig Wilson, Costco’s Director of Food Safety, in an interview with Food Safety News last year.
The need for rapid, do-it-yourself testing is now greater than ever. As of last year, the U.S. Department of Agriculture has proposed to add 6 more strains of pathogenic E. coli to its list of banned bacteria, meaning that producers could soon be testing ground beef for these bacteria, in addition to the more well-known E. coli O157:H7. For companies who sell fresh meat and must make room to store it during testing, realtime detection is a valuable tool.
The system will also work especially well for fresh produce, says Alecilja. Fresh fruits and vegetables that don’t undergo a pathogen-killing step during production or become contaminated post-production are especially dangerous since they will not likely be cooked before eating. Cantaloupes, lettuce, sprouts and tomatoes have all been responsible for multiple serious outbreaks over the past 10 years.
X-MARK technology can also be used to detect other harmful bacteria and toxins, such as tuberculosis and anthrax. For foodborne pathogens, testing can get as specific as the antibody. A more general solution will detect E. coli, whereas a specific one would isolate a specific serotype.
Alecilja says she expects the product to hit markets in about two years.
© Food Safety News