Enzyme-linked immunosorbent assays (ELISA) are used to quantify proteins that are harmful for people with coeliac disease, i.e., wheat, barley and rye prolamins, and to control the safety of gluten-free foods. Prolamins consist of a complex mixture ofproteins that set high requirements for quantification. Modification of proteins further increases their diversity, and risks the reliability of analysis results. The reactivity of prolamins with different prolamin-specific antibodies was examined and clear differences between the recognition of antibodies of prolamin subgroups were shown by western blotting. The results of ELISA demonstrated that barley prolamins are not accurately quantified by R5 antibody. However, with a barley prolamin standard, more precise results were obtained. Further studies were carried out to study how enzymatic or chemical modification affects the measurement of prolamin contents. Both sandwich and competitive R5 ELISAs detected residual rye prolamins after enzymatic hydrolysis in sourdough systems with comparable results. However, after deamidation by acid treatment ELISAs based on R5 and omga-gliadin antibodies failed to measure accurately wheat prolamins. The results demonstrate that current gluten analysis methods cannot accurately quantify prolamins in all food matrices and more work is needed to improve the reliability of gluten quantification.
展开▼
