Gluten-free products must contain less than 20 mg/kg of gluten according to Codex Standard 118-1979 to ensure that they are safe for consumption by celiac disease patients. Enzyme-linked immunosorbent assays (ELISA) are most commonly used to test whether such gluten-free products comply with the regulatory threshold. After two interlaboratory comparisons, the ELISA testkit RIDASCREEN® Gliadin was adopted as a Codex type 1 method in 2006 and as an Official Method of Analysis (OMA) 2012.01 First Action in 2012. The applicability of the method was stated as “in food”, but in 2016 it was restricted to “rice- and corn-based foods”, because only these matrices had been tested within the scope of the collaborative studies. This limitation led to uncertainties for laboratories, because extensive validations were now needed for all foods that were not rice- or corn-based. This is why another international collaborative study was carried out to demonstrate the applicability of this ELISA testkit to a comprehensive set of food matrices. Nineteen different food matrices were incurred with 0-40 mg/kg of gluten and subjected to various processing steps, such as heating. In total, 64 samples were analyzed by each of the 14 laboratories that received two blind coded replicates per matrix and concentration level. The method developer additionally analyzed 46 incurred and 13 blank samples. The between-laboratories relative standard deviation (RSDR) was 10% to 28% over 18 matrices, except fruit juice (RSDR = 39%). Recoveries of incurred levels were 81% to 130%, including the matrices with high heat treatment. The only exceptions were fruit juice and chocolate cake with recoveries of 64% and 57%, respectively. Taken together, the collaborative study demonstrated the accuracy of the method and its applicability to quantitate gluten in a wide variety of gluten-free food matrices.

Applicability of the R5 sandwich ELISA for gluten detection in various food matrices confirmed by an international collaborative study

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.