There is a need for a reliable enzyme-linked immunosorbent assay (ELISA) protocol to detect gluten in foods. This would serve as a basis for further Codex Alimentarius regulations.
The monoclonal antibody R5 raised against a secalin extract may prove to be an essential tool for gluten analysis. This can recognize the celiac-toxic epitope QQPFP, which occurs repeatedly in alpha-, gamma- and omega-gliadins, hordeins and secalins.
In this study, researchers from Spain aimed to develop a highly sensitive and specific sandwich ELISA to quantify low levels of wheat, barley and rye prolamins in foods.
The research team developed a simple sandwich ELISA, based on the use of a single monoclonal antibody (R5) as both the coating and detection.
| The assay was insensitive to the non-celiac-toxic cereals maize, rice and oats.|
|European Journal of Gastroenterology and Hepatology|
They also tested a quantitative cocktail gluten-extraction procedure for heat-processed foods.
The team found that the R5-ELISA was able to identify gliadins, hordeins and secalins with assay sensitivities of 0.78, 0.39 and 0.39 ng/ml, respectively.
They determined that the assay's detection limit was 1.5 ng gliadins/ml (1.56 ppm gliadins, 3.2 ppm gluten).
Furthermore, this system was insensitive to the non-celiac-toxic cereals maize, rice and oats. It was also non-cultivar-dependent.
The team also found that it was able to detect gliadins and hordeins in unprocessed and heat-processed wheat- and barley-based products.
In addition, the assay was able to estimate the gluten content of hydrolyzed foods.
Dr Israel Valdés's team concluded, "We present a new generation of a robust sandwich R5-ELISA with good reproducibility and repeatability".
"Its gluten-detection limit of 3.2 ppm is lower than the existing threshold of 20 to 200 ppm".
"The ELISA, which is equally sensitive to barley, wheat and rye prolamins, is compatible with the quantitative cocktail extraction procedure for heat-processed foods".
"Along with the cocktail procedure, the Working Group on Prolamin Analysis and Toxicity is currently evaluating an R5-ELISA system as proposed by the Codex Alimentarius Commission".