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Explore This IssueJune/July 2013
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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 email@example.com.
The Smartphone: A Tool for Allergen Testing?
Mass spectrometry adapts existing technology to a new purpose. Similarly, the iTube, now in the prototype phase at time of print, turns an ordinary smartphone into a portable allergen testing lab. Currently designed to detect peanuts, this small attachment—22 mm x 67 mm x 75 mm and weighing a mere 40 grams—is a colorimeter that measures the intensity of light to determine if an allergen is present. Its inventor, Aydogan Ozcan, PhD, associate professor at UCLA, states, “Although several products that detect allergens in foods are available, they are complex and require bulky equipment, making them ill-suited for use in public settings. The iTube was developed to address these issues.”