Analysis of barley contamination in oats using R5 and ω-gliadin antibodies

Immunological methods based on monoclonal antibodies with varying specifities towards gluten proteins have been used to control the purity of gluten-free products. Commercially available methods have been developed to detect gluten proteins found in wheat. However, difficulties have occurred in quantifying barley proteins with the same accuracy as wheat proteins. Barley is also a common contaminant in oat products. In this study, oat flour samples were deliberately contaminated with known amounts of barley flour and analysed using two commercial enzyme linked immunosorbent assays (ELISA). The methods were based on an ω-gliadin antibody and an R5 antibody. The results obtained with the R5 antibody were overestimates while the ω-gliadin antibody underestimated the higher barley prolamin content. This study showed that inaccuracies in ELISA assays in quantifying barley contaminations can possibly be eliminated by using a hordein standard. However, it is necessary to know the source of contamination. This would prevent overestimation of the hordein content of gluten-free products. Overestimation unnecessarily reduces the variety of gluten-free products and may decrease compliance to a gluten-free diet.