What is in a beer? Proteomic characterization and relative quantification of hordein (gluten) in beer.

The suite of prolamin proteins present in barley flour was characterized in this study, in which we provide spectral evidence for 3 previously characterized prolamins, 8 prolamins with only transcript evidence, and 19 genome-derived predicted prolamins. An additional 9 prolamins were identified by searching the complete spectral set against an unannotated translated EST database. Analyses of wort, the liquid extracted from the mashing process during beer production, and beer were undertaken and a similar suite of prolamins were identified. We have demonstrated by using tandem mass spectrometry that hordeins are indeed present in beer despite speculation to the contrary. Multiple reaction monitoring (MRM) mass spectrometry was used for the rapid analyses of hordein in barley (Hordeum vulgare L.) beer. A selection of international beers were analyzed and compared to the results obtained with hordein deletion beers. The hordein deletion beers were brewed from grains carrying mutations that prevented the accu...