Proteomic and peptidomic characterisation of beer: Immunological and technological implications

In this study, the protein and peptide fractions of two commercial Italian barley malt beers, made with different processes by the same producer, have been analysed with a combined immunochemical and mass spectrometry approach. The "gluten" content of beer samples, measured with the R5 monoclonal antibody, was below the caution limit proposed by the Codex Alimentarius for gluten-free foods. The proteomic approach allowed to identify a 17 kDa avenin-like protein partially homologous to hordeins, that was particularly abundant in foam, in addition to the already reported barley albumins (Z(4)-barley and ns-LTPs) and to minor amounts of yeast glycolytic enzymes. No intact hordeins were detected, although fragments derived from gamma(3)- and B-hordein were present. In consideration of the many implications of the protein/peptide pattern, these data provide useful information to improve quality and safety of beer.