Determination of Prolamins in Beers by ELISA and SDS-PAGE

Abstract

Coeliac disease is triggered by exposure to the prolamin protein fraction of wheat, barley, or rye. The prolamin content of five lager beers and one wheat beer were analyzed by sodium dodecyl sulfate—polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting and seven lager beers and three wheat beers were analyzed by enzyme-linked immunosorbent assay (ELISA). Most of the lager beers were made from barley and some had varying amounts of rice or corn as adjuncts. One of the beers was “gluten-free”, having been produced from corn and buckwheat without barley. The lager beer samples were gel-filtered before ELISA or SDS-PAGE analysis. Prolamin proteins were found in all but one beer which was made of corn, rice and barley and which was not the “gluten-free” beer. ELISA analysis was done using a commercially available gluten assay kit. For lager beers, a barley prolamin standard for ELISA was propanol-extracted from barley malt instead of using the prolamin standard of the gluten assay kit. As expected, the wheat beers contained much higher amounts of prolamins than the lager beers. The samples were studied by SDS-PAGE to identify different prolamin fractions. Proteins having a relative molecular mass in the range of 8000–17,000 and 38,000 and above were detected in immunoblotting by the prolamin sensitive antibody in the lager beers.