title: Proteome-Based Analysis of Colloidal Instability Enables the Detection of Haze-Active Proteins in Beer.
abstract: Colloidal haze is a serious quality defect of bright beers that considerably reduces their shelf life and is thought to be triggered by hordeins, a class of proline-rich barley proteins. In this work, the proteomes of fresh and old beers were investigated in bottled pilsners and compared to the protein inventory of haze to identify specific haze-active proteins. Haze isolates dissolved in rehydration buffer contained high concentrations of proteins and sugars but provided protein gels with weak spot signals. Consequently, a treatment for the chemical deglycation with trifluoromethanesulfonic acid was applied, which resulted in the identification of protein Z4, LTP1, CMb, CMe, pUP13, 3a, and Bwiph as constituents of the haze proteome. Because only one hordein was detectable and the proline content in haze hydrolysates was lower than those of barley prolamins, our results suggest that this class of proteins is of minor importance for haze development.
authors: Fakultät für Biologie, Proteom- und Metabolomforschung and ‡Technische Fakultät, Fermentationstechnik, Universität Bielefeld , 33615 Bielefeld, Germany.
authors: Fabian
authors: F
authors: Schulte
authors: Fakultät für Biologie, Proteom- und Metabolomforschung and ‡Technische Fakultät, Fermentationstechnik, Universität Bielefeld , 33615 Bielefeld, Germany.
authors: Erwin
authors: E
authors: Flaschel
authors: Fakultät für Biologie, Proteom- und Metabolomforschung and ‡Technische Fakultät, Fermentationstechnik, Universität Bielefeld , 33615 Bielefeld, Germany.
authors: Karsten
authors: K
authors: Niehaus
mesh_terms: D001515:Beer / Q000032:analysis*; D015180:Electrophoresis, Gel, Two-Dimensional; D008401:Gas Chromatography-Mass Spectrometry; D001467:Hordeum / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020543:Proteome / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D020543:Proteome
keywords: Hordeum vulgare; Saccharomyces cerevisiae; barley; beer haze; beer proteome; colloidal instability; hordeins; yeast