These data correspond well with our findings here. In addition, we report for the first time that different brewer’s yeast strains render different beer proteomes; i.e. Exg1 and Bgl2 are identified in the KVL011 beers, whereas in the WLP001 beer only Exg1 is identified. These data strongly indicate that changes

in the beer proteome are strain dependent. Identification of released yeast di-sulphide anchored proteins Uth1, Exg1 and Bgl2 in beer indicates the existence of a reducing environment which can be beneficial for the beer quality by reducing and liberating cell wall anchored yeast proteins. Overexpression of β-glucanases, like Exg1 and Blg2, in genetically modified brewer’s yeast strains, have shown positive effects on filtration of beer, due to increased degradation of β-glucans interfering with filtration [37, 38]. Also in wine fermentations, an elevated production of Exg1 has Selleckchem Bortezomib positive effects on the quality of the end product due to an increased production of volatile products [39]. Uth1 could be speculated to function as an antioxidant or chelator of transition metals in beer due to its conserved cysteine residue motive with a putative Fe-binding motive [31]. A controlled release of these cell wall anchored proteins could contribute to improved BMS-354825 in vivo beer quality. It

should be stressed that our study, using immature beer, only reveals a very limited number of yeast proteins in the beer as compared to the reports of e.g. Fasoli et al. (2010) and Konecna et al. (2012). Rebamipide These authors investigate commercial beers that are most likely fully mature and pasteurized [4, 5], although not specifically stated, thereby explaining the higher number of identified yeast proteins due to cell lysis. Conclusion In this study we find that the proteome of immature beer is dependent on the brewer’s yeast strain used. These data suggest a potential of using different yeast strains to gain wanted protein-related traits of beer, such as e.g. filtration ability and oxidative stability. Acknowledgements This project was financed by the Danish Ministry of Food Agriculture

and Fisheries, project no. 3304-FVFP-07. We thank Chris White from White Labs, San Diego, USA, for providing us with yeast strains. We are also grateful for the sublime 2-DE and MS guidance obtained from Anne Blicher, Birgit Andersen and Avishek Majumder, Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, DK. Electronic supplementary material Additional file 1: MS/MS Spectra’s for single peptide identification. (DOC 48 KB) References 1. Bamforth CW: Perceptions of beer foam. J I Brewing 2000,106(4):229–238.CrossRef 2. Bamforth CW: The foaming properties of beer. J I Brewing 1985,91(6):370–383.CrossRef 3. Siebert KJ, Carrasco A, Lynn PY: Formation of protein-polyphenol haze in beverages. J Agr Food Chem 1996,44(8):1997–2005.CrossRef 4.