Variation in gluten protein and peptide concentrations in Belgian barley malt beers

Abstract

Gluten is the main family of storage proteins found in barley. During malting and brewing, some of the barley malt's proteinaceous material is hydrolysed into peptides or to amino acids. Most of the gluten proteins are removed with the spent grains and with hot‐ and cold‐breaks. However, some gluten proteins and especially gluten‐derived peptides can remain throughout the brewing process and will hamper the gluten‐free (≤20 ppm) status of the beer. In this work, three production batches (a, b and c) of 51 Belgian barley malt beers from 24 breweries were analysed with the sandwich (R7001) and competitive (R7021) Ridascreen gliadin R5‐ELISA to quantify gluten proteins and peptides. Although the majority of the beers contained low‐gluten protein concentrations of ≤20 ppm (a/45, b/47, c/48), only a minority were truly gluten‐free with ≤20 ppm gluten peptides (a/18, b/17, c/15). The grain bill had no influence on the measured gluten concentration, but the use of (combined) clarification techniques and presence of wheat malt in the grist was respectively a positive and negative influence. Ten beers, from four breweries, were gluten free in all analysed samples. These included two wheat beers, reflecting the importance of effective clarification in the management of gluten. These results explore the feasibility of the production of gluten‐free barley malt beers. Copyright © 2018 The Institute of Brewing & Distilling

Gluten Assessment in Beers: Comparison by Different Commercial ELISA Kits and Evaluation of NIR Analysis as a Complementary Technique

“…Considering that ale yeast is used for gueuze beer production, results from the present research are completely in agreement with those reported with Belgian beers. Indeed, no correlation exists between the original extract of barley beers and gluten content [ 29 ], which we confirmed. As a whole, and supported by the literature, both the main ingredients as well as the yeasts used are relevant contributors to the gluten content of beers.…”

“…Similar inferences were made in 51 commercial Belgian barley malt beers, measured by the same kits. R5 competitive ELISA identified less than half the number of GF beer than did direct assay (18 vs. 45) [ 29 ]. However, in the present approach, the noncompetitive kit comes from a different manufacturer and is a direct ELISA and thus not based on sandwich methodology.…”

“…Another reason could be related to the brewing process. The addition of malted cereal or not, the use of clarification processes, such as filtration, centrifugation, or a cold-break step, can influence the gluten content in beer [ 29 ]. The malting process implies germination of the grain that provides the necessary proteases to degrade storage proteins such as hordeins [ 9 ].…”

“…Similar results were found in 51 Belgian beers measured by R5 competitive ELISA. They analyzed 13 beer types and highlighted that in wheat and gueuze beer, gluten content was extensively most abundant [ 29 ]. Considering that ale yeast is used for gueuze beer production, results from the present research are completely in agreement with those reported with Belgian beers.…”

“…In other studies, commercial beer analyzed by R5 competitive [ 36 ], Skerrit sandwich [ 33 ] or G12 competitive ELISA kits [ 10 ], also determined less than 20 mg/kg of gluten; 28%, 50%, and 27%, respectively (beer proportion was of 7 out of 25, 25 out of 50 and 8 out of 30). In their research, Watson et al shed light on the divergences among studies [ 29 ]. In their gluten content quantification by R5 competitive ELISA kit, they described that 10 out of 51 beers did not contain more than 20 mg/kg of gluten in any of the three batches analyzed.…”