RI-ERP-FINALACTION-Recommendations
AOAC RESEARCH INSTITUTE AOAC OFFICIAL METHODS OF ANALYSIS (OMA)
OMAMAN-20: R-Biopharm, Qualitative Detection of Gluten on Surfaces and In Processed and Non- Processed Products by R5 Immuno-Chromatographic Dip Stick Study Director: Dr. Markus Lacorn & Thomas Weiss, R-Biopharm AG, An der neuen Bergstraße 17, 64297 Darmstadt, Germany General comments about the method: ER 1 In-house validation report was not available to review the method. ER 2 The method is well established and is known to generate false positives with soy products (e.g., soy milk) that the use of milk powder does not eliminate. This is never mentioned but instead the use of milk powder is presented as a solution~ .The authors should re-write the documents with a more open / critical perspective. -There is also a serious question of why they did not use corn flour that was totally free of gluten and prepare cookies with known levels of 0, etc etc. Method is well written and the experimental details and instructions provided to participants were very clearly laid out. The pre-collaborative tests were organized properly and sufficient time was given to participants to demonstrate proficiency prior to undertaking to analyze the collaborative method samples. The method is very sensitive, I wonder that maybe -looking at the action level of 20 mg/kg- the LFD method could be too sensitive? Another point as with the R5 sandwich, the gluten content = 2 x gliadin. Unifying results to gluten content will be helpful instead of using mg/kg gliadin The dip stick assay based on R5 antibody is meant for a rapid qualitative visual detection of gluten in processed and non-processed samples. The scope of the method to detect intact gluten (prolamins) includes matrices like corn, wheat, rye and barley. The non-processed samples are extracted in 60% ethanol and processed samples are extracted in a proprietary cocktail provided in the kit. The assay has been designed to detect gluten well below the threshold level of 20 mg/Kg. The reproducibility of the assay has been evaluated in corn sample and processed samples like cookies and corn snacks. The assay provides positive results above 2.5 mg/kg in non-processed foods and above 4 mg/kg in processed foods. The positive results are produced if a surface contains more than 1to 2 mcg gliadin/100 cm2. . The R5 dipstick has been in the market for a long time. It’s applicability to food matrices are recognized. However, food surfaces application appears to be an afterthought. No validation data were presented or reported elsewhere. As mentioned in the manuscript, a positive band can have non-uniform color intensity due to in-homogenous distribution of gluten on the dipstick sample pad. This may be a sampling protocol flaw and may give an inconsistent result. ER 3 ER 4 none. ER 5 ER 6 ER 7 ER 8 NA Well designed study with appropriate controls. study includes validation of methods for both processed and non-processed foods none that was obvious. Other dipsticks have been more rigorously validated with inclusion of cross-reactivity (inclusivity / exclusivity agents). and use of surface testing. The authors clearly identify gliadin as what is being measured by the test kit and this is made Page 5 of 13 ER 2 ER 3 ER 4 I think the method looks pretty good. Some issues with the manuscript Pros/Strengths of the Manuscript: ER 1
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