Thank you to Thomas Grace of Bia Diagnostics, www.biadiagnostics.com for sharing his expertise on Lateral Flow Devices
What are lateral move units (LFDs)?
LFDs are used to qualitatively (is gluten present) or semi-quantitatively (what amount of gluten is present) determine whether gluten is present in a food product. There are a number of LFDs available on the market for testing meals for gluten, including the Ridascreen Fast Gliadin manufactured by R-biopharm, EZ Gluten manufactured by Elisa Technologies, AgraStrip Gluten G12 Test Package manufactured by Romer Labs, and Gluten Tox manufactured by Biomedal Diagnostics. Specifics on each of these checks are included on the finish of the Q & A piece.
How do LFDs work?
LFDs are often what we consider as “dipstick” exams. Most make use of sandwich sort methodologies. They utilize a line of fastened antibody on a surface strip and a second antibody conjugated with coloured “nano” measurement particles (on the sample addition end of the strip). When a liquid pattern extract is utilized to the strip, the conjugate and the sample begin to migrate across the floor of the strip together. If the sample extract has the protein or compound present (gluten) and the conjugate can acknowledge its epitope (binding website), beneath the best circumstances they may bind together. Now that they are “hooked” collectively as they come in touch with the road of antibodies which might be fastened to the strip, these antibodies may also bind to the protein forming a sandwich complicated, “sandwiching” the protein (gluten) between the 2 antibodies. Because the conjugate complicated starts to accumulate on the floor of the strip the “nano” particles start to turn into visible. The more protein (gluten) in the sample the more antibody-protein-conjugate binding will happen and the darker the road turns into.
It must be famous that until the LFD has been shown to reliably detect pure wheat, barley or rye cultivars (e.g. undiluted wheat flour), it ought to have a hook line to avoid false unfavorable outcomes with excessive concentrations of gluten. A hook line is just a small quantity of analyte protein on the surface of the strip that may seize any “free” antibody that has not been sure with the sample. A constructive hook line exhibits that the strip shouldn’t be over loaded and the assay is legitimate.The shortage of any hook line alerts the consumer that the check is over loaded and the pattern ought to be diluted additional.
Beneath what circumstances is it okay for manufacturers to use LFDs?
LFDscan be nice instruments for helping producers in defining their Hazard Analysis Important Control Level packages and figuring out if they’re in compliance with their particular packages. Manufacturers can use LFDs to check uncooked components, to verify surfaces between product runs to ensure they are clear, and in some instances to check completed merchandise. In every case, LFDs require validation to 1) show compatibility with the producer’s product, 2) show the power to detect recognized amounts of gluten in the product (spiked/recovery), and three) prove comparable results could be found with the R5 ELISA technique which most people think about the “gold standard” for gluten testing.
How would a manufacturer go about validating an LFD?
Validation often would include taking an ingredient, ingredient combine, and/or finished product unfavorable management and operating the check on the sample. If the check is damaging, the manufacturer would then take the samples or pattern mixes and add a 20 part per million gluten spike (a proportional mixture of wheat gliadin, barley hordein, and rye secalin) into every sample (the gluten spike ought to be less than 10% of ingredient) and run the check once more to ensure they get a constructive outcome for each of the spiked samples.
If all samples are constructive on the degree expected, they might then take pure wheat flour and check it to be certain they don’t get false adverse results with an over abundance of contaminant. Also, finished products must be periodically checked (each batch if produced on shared gear or each few months if not) by way of third celebration labs utilizing CODEX/AOACRI permitted methods.
What are the restrictions of utilizing a LFD to check food for gluten?
Manufacturers using LFDs should remember that these checks:
- Are qualitative methods used to display for specific proteins or compounds.
- Require two antibody binding websites to be present on the gluten protein or peptide so as for the methods to detect gluten. If only one antibody binding website is present (as will be the case with extremely hydrolyzed foods and components) than no sandwich complicated may be shaped and no check line will probably be seen and a false destructive outcome can be reported.
- Are only meant for detecting hint amounts of protein. When more than trace amounts are current, false unfavorable results might occur.
- Should never be used for finished product validation in and of themselves. Solely a totally validated technique corresponding to ELISA or PCR or HPLC must be used for validating completed products.
Should shoppers use LFDs to check products for gluten?
Consumers usually shouldn’t use these units for residence use because of the acute variance in meals merchandise–each LFD must be validated for each specific product. Why? The burger they make at residence shall be totally different from the burger they get at McDonalds. The fats content shall be totally different. The salt content will probably be totally different. The sauces shall be totally different. All of these variables may make one burger suitable with the LFD and the other not. Something as “innocent” as a pinch of salt or a bit of vinegar may be all it takes for an LFD to produce a false damaging or false constructive outcome. For many shoppers it’s impractical or unimaginable to validate each product they might want to check before they really check it.
Ridascreen Quick Gliadin: From the Producer*
- “RIDA® QUICK Gliadin can be used as a swab test for the gluten determination on surfaces in the hygiene control and for the qualitative detection of gliadin/gluten in raw material. The test should only be used for the detection of small amounts of gluten (contaminations). The gliadin/gluten determination can be carried out for numerous raw materials after a simple ethanol extraction. Further applications, e.g. for processed foods and chocolate, are available upon request.”
- “The immunochromatographic test employs the monoclonal R5-antibody which is specific for the detection of gliadin from wheat and prolamins from rye and barley.”
- “Results are read visually. Generally, the higher the analyte level in the sample, the stronger the red color of the test band will be.”
*From producer web site
EZ Gluten: From the Producer*
- “The EZ Gluten Test is an easy to use home test that will quickly detect the presence of gluten in foods. It is sensitive enough to detect gluten as low as 10 parts per million (ppm). This simple test is also small and portable enough for use in restaurants or when traveling. It can be used to test individual ingredients in foods, or to test finished and cooked products.”
- “The EZ Gluten Test uses the anti-omega gliadin antibody developed by Skerritt and Hill for detection.”
- “The test strip can be read visually for the presence of gluten in the sample.”
Tricia’s notice: The EZ Gluten makes use of the omega-gliadin antibody that has very low cross-reactivity with barley (4 to eight %). If barley is a contaminant within the meals product it won’t be detected (or severely underestimated) using this check.
*From product package deal insert
AgraStrip Gluten G12 Test Package: From the Producer*
- “The AgraStrip Gluten G12 Test Kit is a lateral flow immunochromatographic assay that determines a semi-quantitative level for the presence of gluten.”
- “The Test Kit uses a new monoclonal antibody called G12 that specifically recognizes the pathogenic fragment of the gliadin protein present in gluten. This fragment is called 33-mer and triggers the auto-immune reaction in celiac patients.”
- “The G12 antibody used in the test kit reacts with some oat varieties.”
- Outcomes may be read visually.
*From product package deal insert
Gluten Tox: From the Manufacturer*
- “GlutenTox Home is a rapid and user-friendly test for the detection of gluten in food and drinks which is harmful for people who suffer from celiac disease.”
- “GlutenTox Home contains a new antibody called G12. It was developed to specifically recognize the toxic fraction of gluten present in wheat, barley, rye, and oat that triggers the auto-immune response in celiac patients.”
*From producer website
Tricia’s word: Within the US oats not contaminated with wheat, barley, or rye are allowed in gluten-free diets. Nevertheless, controversy over oats nonetheless exists.
Dietitians attending FNCE 2011: Please make plans to be a part of us at the pre-FNCE workshop, “Celiac Disease Toolkit: Guiding Your Patients through the Gluten-Free Diet” on Saturday, September 24 from 9 am to three:30 pm. Thomas Grace of Bia Diagnostics shall be in attendance and shall be discussing testing strategies for gluten, together with lateral movement units.
Reminder: I’ve began a new website Gluten Free Watchdog (www.glutenfreewatchdog.org) to check merchandise for gluten. Merchandise from Arrowhead Mills, Authentic Meals, Bob’s Pink Mill, Common Mills, Holly’s Oatmeal, Mary’s Gone Crackers, Namaste Foods, Orgran, and Pamela’s have been tested. Products to come embrace those made by Lundberg Farms, Assume Skinny, Twin Valley Mills, and Novartis (Benefiber). Please go to the location and browse the precise merchandise tested and share your thoughts about what you desire to to see tested next.