A new study indicates that certain barley beers labeled gluten-free may still contain trace gluten residues capable of affecting people with celiac disease, even when standard antibody tests report them as safe. Researchers at the Leibniz Institute for Food Systems Biology compared two common ELISA antibody methods with a newly developed mass spectrometry technique. Results revealed that the tests do not always detect every celiac-active peptide present. The work appears in Applied Food Research.
Gluten refers to proteins in wheat, rye and barley. Under EU and Codex Alimentarius rules, foods qualify as gluten-free when gluten stays at or below 20 milligrams per kilogram. This threshold allows most individuals with celiac disease, an autoimmune condition of the small intestine, to consume such products without symptoms.
Barley beer naturally contains gluten. Breweries use processing methods to reduce it and then apply standardized ELISA tests to confirm compliance. These assays rely on antibodies to identify immunogenic protein fragments generated during gluten breakdown.
The team tested four regular beers and 21 gluten-free barley beers. While one ELISA method found all gluten-free samples below the limit, the second method detected four samples slightly above it. The mass spectrometry approach identified 44 peptides known from literature to trigger celiac responses, with 29 appearing in the gluten-free beers. Seventeen of these peptides had structures the ELISA antibodies cannot recognize.
The findings suggest gluten-free barley beers are generally safe yet highlight inconsistencies between antibody tests and their inability to catch every relevant peptide. Further studies are required to determine whether the additional peptides pose meaningful health risks, though their concentrations remained low. Researchers note that combining rapid tests with mass spectrometry could eventually improve safety of gluten-free foods.
