Immunochemical determination of gluten in malts and beers

Abstract

The gluten content in different varieties of barley and malts, and in different types of beers, was determined by a ‘sandwich’ enzyme immunoassay (RIDASCREEN® Gliadin kit). The gluten levels in barley wheat, rye and spelt malts ranged 18.8–45.0, 44.0–68.0, 41.6 and 21.2 g kg–1, respectively. When various types of beer were compared, the gluten concentration increased as follows: alcohol-free beer (<3.0), lager beers (<3.0–8.7 mg l–1), stouts (9.0–15.2 mg l–1) and wheat beers (10.6–41.2 mg l–1). When 10 Czech lager beers were analysed, using both sandwich and competitive ELISA, the results showed that the latter method provided values several times higher than the former. Gluten balance was carried out during the brewing process, starting from the raw materials and terminating at the final beer. Gluten levels decreased due to precipitation during the mashing process, primary and secondary fermentation and, lastly, as a result of adsorption during beer stabilization. The gluten content in beer is, thus, approximately three orders of magnitude lower than in the raw malt.