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Smaller, Stronger, Faster Labs
Innovations in food safety labs leading the industry
by Neil Canavan
Food, glorious food!/We’re anxious to try it/Three banquets a day/That’s our favorite diet! —Charles Dickens, Oliver Twist
In these non-Dickensian times, the availability of food is not as much of an issue as concerns about food safety. Food is pouring in from all over the world, but ensuring its safety is a complex task. Food safety is inherently bound up in issues related to time, such as how long it takes to detect a problem or contaminant. And because time is money, there’s money to be made—or granted—in exploring the future of rapid detection.
“If you look over the last 12 months, two things have happened that are relevant,” said Marcos Cantharino, global business director at DuPont Qualicon in Wilmington, Del. First, there was a federally mandated determination, in contrast with the previous administration, to protect the consumer from foodborne diseases. And, second, “the government is looking for solutions that are either new technologies or new processes that can be in place at the source within food companies or at suppliers in general.”
As this mandate plays out in the legislative process, some funding is already available for innovation in rapid testing. The Defense Advanced Research Projects Agency recently invited proposal submissions for Systems and Assays for Food Examination methods of rapid detection, identification, and subtyping of Salmonella.
The Qualicon team is particularly interested because the microbe-detecting BAX system is their star player. The company recently received Emergency Response Validation certification for the detection of Salmonella in peanut butter, a distinction awarded by the Association of Official Analytical Chemists (AOAC).
The BAX system is streamlined for rapid detection. “Basically it’s a PCR [polymerase chain reaction] system, but we’ve eliminated all but a few of the 20-plus steps that might normally be taken in the PCR process,” said Cantharino. “We take all of the reagents that you would need for home brew PCR and put them into a tablet. … Just hydrate the tablet with the lysate and run it through the machine.” The results are noninterpretive: Red means you have a problem; green means there is no problem.
The simplicity and size of this benchtop system, as well as Qualicon’s global technical support, allow for on-site testing, a critical need for an increasingly globalized food industry. “We take some very sophisticated and advanced technology and make it into user-friendly applications. You don’t have to have a staff of advanced molecular biologists to use our product,” Cantharino said.
BAX, which recently received AOAC validation for Listeria and Vibrio assays, will make available, in the near term, new rapid tests for E. coli 0157:H7 and Cronobacter, “an important bug for infant formula companies.”
Currently, the rate-limiting step in microbe detection is enrichment. One must grow a large population of a given bug to detect it. Daniel Fung, PhD, a professor of food science at the University of Kansas, is working to solve this problem. “I’ve developed a method which is excellent. There’s an enzyme Oxyrase that, when added to the culture medium, stimulates growth of many pathogens. This cuts the enrichment time from 12 hours to as few as four.” (J Rapid Meth Autom Microbiol, 2007). The discovery has already made its way into proprietary commercially available media. Dr. Fung did not patent the enzyme for enrichment purposes.
Another microbial strategy subject to recent improvement is concentration, or packing bugs into a smaller and therefore more detectable space. Matrix MicroScience, in Golden, Colo., recently launched the fully automated Pathatrix Auto system that relies on immunomagnetic separation technology. “This system is truly an innovation,” Dr. Fung said. Pathatrix uses paramagnetic particles to selectively bind target organisms from a wide range of complex matrices.
“It has a circulating system. You input all 250 mL of broth, and the first pass captures, say, 20% of microbes in suspension.” With a few more passes, a full pathogenic harvest has been reaped in less than an hour, he said.
Key to the success of this and related technologies is keeping them user friendly. “A long time ago, we asked people not to do microbiology unless they have a very good lab,” said Dr. Fung. The company encourages the food producer to send samples out for testing so as not to contaminate the facility. But the methods and machines have come a long way.
“I was just at a meeting where someone said that in the time it takes to prepare and send a sample by FedEx, the company can already have the data if it’s done in house.” These days, even a small company can afford the price and space for a small biological hood, and, often, that is all that is needed.
This has piqued both domestic and global interest. “There are many more workshops on rapid methods popping up right now,” said Dr. Fung, a leading speaker in the field, who was in Abu Dhabi last year and in Cancun in recent weeks. Next year, he plans to attend workshops in Hong Kong, Turkey, and Greece. “I’ve been going all over the place and doing workshops; the excitement is there.”
Mike Doyle, PhD, director of the Center for Food Safety at the University of Georgia, acknowledges the need for speed. “If we’re going to do finished product testing—and the signs of the time are saying we are or the outbreaks are going to be more killing—you’re going to have to have quick test, because it’s a test-and-hold situation.”
The shipment of that perishable product, wherever it may be, is waiting on the test results. Rapid testing is key. “The standard right now is 24 hours, and some say they can get it down to 12,” Dr. Doyle said. But the real need is testing in real time. “It’s where a product passes under a sensor and you have your answer. That’s where we need to go,” he said.
Dr. Doyle will serve as science advisor to Roka Bioscience, a recent spin-off from Gen-Probe in San Diego, Calif. “This detection technology will rely on 16S RNA, which gives you a whole lot more signal than you get with DNA-based assays.” An enrichment phase could be cut from 24 to four hours with this technology, he said.
New Techniques in Contaminant Prevention
Dr. Doyle believes that the science/business world will continue to spearhead innovation in detection; however, new techniques for contaminant prevention are coming from academia. Dr. Doyle’s group, for example, just had a major breakthrough while working on an effective chemical treatment to inactivate pathogens such as Salmonella, Listeria, and E. coli without ruining the product. Because many compounds kill, “the hard part is to retain the quality characteristics, especially something sensitive like lettuce.”
Dr. Doyle’s new combination of levulinic acid and the detergent sodium dodecyl sulfate has not only been shown to have high activity, including on biofilms, but it has no negative impact on organic tissue, he said (J Food Prot. 2009;72(5):928-936).
Prevention also concerns Alan Shema, product manager for consulting and testing services at Mocon in Minneapolis. “We’ve seen growing interest in testing to understand the interaction between the packaging materials and the product:” specifically, gas permeability or residual oxygen. The presence of oxygen may change the flavor or aroma of a product and allow the growth of microbes.
David Plunkett, Center for Science in the Public Interest
The FDA is much more focused on prevention as a strategy for food safety, and they are much more willing to challenge claims by the industry.
Testing for oxygen within a package requires a headspace analyzer. Mocon’s device is the recently upgraded Pac Check Model 450 EC; EC is the upgrade. “That’s electro-chemical. It ensures accuracy while at the same time bringing down costs,” Shema said.
Far more futuristic is the recently launched OpTech 02Platinum. “This is a nondestructive O2 analyzer. With Pac Check, the package had to be pierced. With OpTech, there is a little platinum target, or dot, that you can actually place inside the package,” Shema said. In the presence of oxygen, the platinum chemistry of the dot produces a detectable fluorescence. “It’s portable, and it looks like the scanner gun you see in stores.”
Small Molecule Detection
Mass spectrometry is king of the small molecule domain, with future innovations focused on tweaks to the overall approach. One of the biggest challenges has been the identification of an unknown; for example, who was really looking for melamine when it was detected? The recently introduced Exactive, a benchtop liquid chromatography-mass spectrometry (LC-MS) system by Thermo Fisher, highlighted in these pages last January, was designed to do just that. Exactive is finding its niche, often coupled with other separation techniques. At September’s AOAC meeting, Milena Zachariasova, of the Czech Republic’s Institute of Chemical Technology, used Exactive coupled with TurboFlow technology to resolve unknown mycotoxins in beer.
“You can take a pretty dirty sample, and as long as there are no actual particles in it, inject it into the TurboFlow column,” said Yolanda Fintschenko, PhD, manager of food safety technologies at Thermo Fisher. Because of the flow, the big molecules, proteins, and carbohydrates pass through the system, while smaller molecules diffuse quickly into the packing material and are retained on the column. “Then you switch solvent and elute the fraction you’re interested in, the residue. That can eliminate a lot of complicated steps.” Dr. Fintschenko said that customers report a reduction in running time for sample prep from five hours to about 30 minutes.
Paul Zavitsanos, worldwide food industry manager for the mass spec instrument maker Agilent, said he is concerned with placing high tech tools in the increasingly low tech environments of end product testing. “Frankly, you don’t need a stack of PhDs to run these tests. In this day and age, an Agilent person comes in and sets up the equipment, and all you have to do is learn how to press the start/run button.” The problem arises in the interpretation of the results.
Food safety is a continuously moving target, with new metabolites, new impurities, new contaminants, and new varieties of foods. “So what kind of skill is required, and how can we move that level of skill throughout the global environment to allow people to modify existing methods? That’s the challenge,” Zavitsanos said.
Increasing attention is also being directed at the nutritional content of food. “How much fat is there? Does it contain lycopene? Customers want to know these things now,” he said. Agilent has just released a new protocol for its 1290 Infinity LC System that will help identify fat-soluble vitamins.
Prevention of Problems
Pending legislation sponsored by Sen. Richard Durbin (D-Ill.) will, if passed, greatly enhance the U.S. Food and Drug Administration’s (FDA) authority to ensure food safety. “Things are looking very good for improvements in the system,” said David Plunkett, senior staff attorney at the Center for Science in the Public Interest. The aim is to put the power back on the consumer’s side.
“The FDA and USDA [U.S. Department of Agriculture] have been much more responsive to consumer concerns than they were under the previous administration,” Plunkett said. “They are much more focused on prevention as a strategy for food safety, and they are much more willing to challenge claims by the industry.”
For the industry, the driving force going forward will be the ability to rapidly demonstrate the safety of your product and the readiness to rigorously prove it when needed. ■