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The Future of Allergen Testing with Mass Spectrometry
by Maybelle Cowan-Lincoln
For many people, trying new foods is a delicious adventure. But for consumers with potentially fatal food allergies, it can be a dance with death, relying on incomplete product labeling and inaccurate testing methods. But a new focus for an old technology has given allergy sufferers hope that in the near future they can know how safe what they are about to eat really is.
Federal labeling regulations are in place, but they are hardly comprehensive. The Food Allergen Labeling and Consumer Protection Act of 2004 requires manufacturers to include a “contains” statement, a clear list of ingredients that are defined as allergens in the U.S. by the “big eight” list: Eggs, milk, wheat, peanuts, soy, tree nuts, fish, and crustacean shellfish. The problem arises when the allergens are not intended ingredients. If the food is made in the same facility and on the same equipment as food containing allergens, some of these potentially dangerous ingredients may wind up cross-contaminating other foods.
To warn consumers of possible cross-contamination, companies often adopt advisory statements revealing that a food was produced in a facility that also processes allergens. But these statements are completely voluntary; they are not required by labeling laws.
Conventional Testing Tools
Warning statements cannot be a substitute for Good Manufacturing Practices. Companies are still expected to make a good faith effort to ensure foods that are not supposed to contain allergens are, in fact, allergen-free. That is where allergen testing comes in. But just how reliable are conventional testing technologies?
Typically, companies rely on two types of tests: polymerase chain reaction (PCR) and enzyme-linked immunosorbent assays (ELISA). PCR is a fast and inexpensive method to identify DNA. It amplifies, or copies, small segments of DNA until a large enough sample is grown to determine if an allergen is present. Although the method can identify the DNA of milk, peanuts, soy, walnuts, hazelnuts, fish, and crustaceans, there are several pitfalls to this method that can allow an allergen to slip through the cracks. The most notable is that PCR detects the presence of DNA, but not proteins. Egg whites and milk, significant allergens, contain little or no DNA, but high quantities of protein. Therefore, this method is not reliable for these foods.
The ELISA method, on the other hand, detects antibodies in a sample that indicate the presence of allergens, but a separate kit is required for each allergen, which can get expensive. Consequently, companies often do not test products for the presence of all possible allergens. They do a cost-effectiveness analysis and select the top one, two, or three allergens most likely to be present. Any others can go undetected.
Mass Spectrometer Advantage
A newer technology for detecting allergens is mass spectrometry (MS), a process that identifies proteins and peptides with a high level of accuracy. Unlike other methods, MS directly detects allergens by breaking them down into peptides, or short strings of amino acids that link together to form larger proteins. This platform offers several advantages over conventional detection methods.
Bert Popping, PhD, director, scientific development at Eurofins, an international analytical testing company which is known to have pioneered the use of MS for food allergen testing, explains the reliability of results by MS equipment from the way they detect peptides rather than entire protein structures. Proteins can be degraded by processing, cooking, etc., and an altered structure may not be recognized when an assay is looking for an allergen. However, the shorter peptides are more likely to be still intact after processing and therefore remain detectable by MS. And MS detects more than one peptide per allergen, so should one be degraded, the offending substance can still be discovered by at least one or two other peptides.
Another reason mass spectrometers are more accurate is they directly detect components of the allergen, unlike PCR or ELISA.
Dr. Popping sums it up by stating, “The beauty of mass spectrometry is that you are looking at much smaller sequences, so even if some part is broken away, usually you still have sufficient structure left so the peptide is detectable. And it is safer because instead of relying on finding just one target, you are looking at several.”
To look at this another way, think of a protein as a building. Imagine the building being “broken down” by an explosion. If someone wanted to identify what kind of building it had been, they need only to look at the pieces. A jumble of couches, bedroom furniture, and kitchen appliances points to a residential apartment building, while desks, filing cabinets, and computer hardware indicate an office building. Similarly, the peptides that remain after the protein is broken down by MS determine what protein existed before the test.
Another reason mass spectrometers are more accurate is they directly detect components of the allergen, unlike PCR or ELISA which indirectly detect them through DNA or antibodies. This allows high-protein, low-DNA allergens like milk and egg whites to be detected. In addition, mass spectrometers can multiplex, detecting all of the big eight in one test–making them faster, easier, and less expensive to test for multiple allergens than a series of ELISA assays.
A recent study performed by Dr. Popping confirmed the reliability of the method. Seven allergens, including eggs, milk, and soy, were baked into bread and tested with PCR, ELISA, and MS. The accuracy of PCR and ELISA tests was mixed; sometimes they detected the allergens, but sometimes they did not, and they often underreported how many parts per million (ppm) were present in the sample. Conversely, MS results were unerringly accurate, detecting each allergen every time and in the correct ppm.
Cost is another potential benefit of MS, especially when testing for multiple allergens. One MS test performed by a third-party lab can possibly cost a food manufacturing company more than one ELISA kit, but less than three kits. Therefore, once a company is targeting three or more allergens, MS technology provides a cost savings opportunity that becomes more efficient with each additional targeted protein.
There are, however, a few obstacles preventing MS units from taking their place as a first-line allergen detection method. Considered a newer platform in the food industry, it suffers from the perception that it is highly expensive and technically complicated. While it is true MS equipment requires a significant capital outlay, most testing labs already own the machines, and their technicians are well-versed in their operation. This technology has been in use for other purposes and other industries for years.
According to Dr. Popping, “When people in a community are confronted with change, it takes time for them to adapt. But I am confident that MS will take its place as a first-line detection method because we are seeing more research done and more funding dedicated to developing this technology.”
Cowan-Lincoln is a science/technical writer based in New Jersey. She is a frequent Wiley-Blackwell contributor who has been featured in numerous publications. Reach her at firstname.lastname@example.org.