Protein Z
Protein Z is a protein with a molecular mass of 40 kDa found in the barley endosperm, though its biological function is unknown.[1][2] It becomes glycated, mainly during the malting process.[3] Protein Z survives the malting and brewing process and it is the most abundant protein found in beer, ranging from about 20–170 mg/L.[1][4][5]
Protein Z has often been credited with playing a significant role in foam stability (and not foam formation), although this notion has been called into question by a study demonstrating that beer without Protein Z still maintains a comparable level of foam stability.[6] In other words, Protein Z appears to have little or no role in foam stability.[1] However, similar to LTP1, Protein Z contains free thiols on its two cysteine residues, so it very likely plays an active role as an antioxidant in beer, although not to the extent of LTP1.[4] See Protein for more information.
See also[edit]
References[edit]
- ↑ a b c Steiner E, Gastl M, Becker T. Protein changes during malting and brewing with focus on haze and foam formation: a review. Eur Food Res Technol. 2011;232:191–204.
- ↑ Jin B, Li L, Liu GQ, Li B, Zhu YK, Liao LN. Structural changes of malt protein during boiling. Molecules. 2009;14(3):1081–1097.
- ↑ Bobálová J, Petry-Podgórska I, Laštovičková M, Chmelík J. Monitoring of malting process by characterization of glycation of barley protein Z. Eur Food Res Technol. 2010;230(4):665–673.
- ↑ a b Lund MN, Lametsch R, Sørensen MB. Increased protein–thiol solubilization in sweet wort by addition of proteases during mashing. J Inst Brew. 2014;120(4):467–473.
- ↑ Krottenthaler M, Back W, Zarnkow M. Wort production. In: Esslinger HM, ed. Handbook of Brewing: Processes, Technology, Markets. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA; 2009.
- ↑ Picariello G, Mamone G, Nitride C, Ferranti P. Proteomic analysis of beer. In: Colgrave ML, ed. Proteomics in Food Science. 2017:383–403.