Protein: Difference between revisions

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 ===Oxidation===
-Oxygen introduced into the mash causes the aggregation of "gel-proteins" (certain types of hordeins) as well as larger polypeptides.<ref name=adb/><ref name=poyri>Pöyri S, Mikola M, Sontag-Strohm T, Kaukovirta-Norja A, Home S. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2002.tb00550.x The formation and hydrolysis of barley malt gel-protein under different mashing conditions.] ''J Inst Brew.'' 2002;108(2):261–267.</ref><ref name=celus/><ref name=karhan/><ref name=jinspe>Jin YL, Speers RA, Paulson AT, Stewart RJ. [https://www.researchgate.net/profile/Robert-Speers/publication/285959138_Effects_of_b-Glucans_Shearing_and_Environmental_Factors_on_Wort_Filtration_Performance/links/587e215408ae4445c06f6ff2/Effects-of-b-Glucans-Shearing-and-Environmental-Factors-on-Wort-Filtration-Performance.pdf Effects of β-glucans, shearing, and environmental factors on wort filtration performance.] ''J Am Soc Brew Chem.'' 2004;62(4):155–162.</ref> They become insoluble at higher mash temperatures and settle as a doughy layer on top of the spent grains in a traditional lauter tun. This layer is often called the teig or ''Oberteig'' (which means "upper dough" in German), and it can prevent clarification, and slow down or stop lautering and/or recirculation.<ref name=stephenson>Stephenson WH, Biawa JP, Miracle RE, Bamforth CW. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2003.tb00168.x Laboratory-scale studies of the impact of oxygen on mashing.] ''J Inst Brew.'' 2003;109(3):273–283.</ref> Small starch granules, β-glucans, and pentosans, which in turn are linked to proteins, also take part in the formation of complexes, which lead to increased dough formation. They can also hinder the release of starch granules and thus the effect of the amylases. The formation of gel-protein is minimal at low temperature (e.g. 118°F, 48°C) possibly due to the action of proteases, but during and after the saccharification rests (e.g. 145°F, 63°C), the amount of gel-protein rises rapidly when the mash is oxidized. The ''Oberteig'' tends to become especially prominent if the mash is recirculated, or it can also form during vorlauf.
+Oxygen introduced into the mash causes the aggregation of "gel-proteins" (certain types of hordeins) as well as larger polypeptides.<ref name=adb/><ref name=poyri>Pöyri S, Mikola M, Sontag-Strohm T, Kaukovirta-Norja A, Home S. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2002.tb00550.x The formation and hydrolysis of barley malt gel-protein under different mashing conditions.] ''J Inst Brew.'' 2002;108(2):261–267.</ref><ref name=celus/><ref name=karhan/><ref name=jinspe>Jin YL, Speers RA, Paulson AT, Stewart RJ. [https://www.researchgate.net/profile/Robert-Speers/publication/285959138_Effects_of_b-Glucans_Shearing_and_Environmental_Factors_on_Wort_Filtration_Performance/links/587e215408ae4445c06f6ff2/Effects-of-b-Glucans-Shearing-and-Environmental-Factors-on-Wort-Filtration-Performance.pdf Effects of β-glucans, shearing, and environmental factors on wort filtration performance.] ''J Am Soc Brew Chem.'' 2004;62(4):155–162.</ref> They become insoluble at higher mash temperatures and settle as a doughy layer on top of the spent grains in a traditional lauter tun. This layer is often called the teig or ''Oberteig'' (which means "upper dough" in German), and it can prevent clarification, and slow down or stop lautering and/or recirculation.<ref name=stephenson>Stephenson WH, Biawa JP, Miracle RE, Bamforth CW. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2003.tb00168.x Laboratory-scale studies of the impact of oxygen on mashing.] ''J Inst Brew.'' 2003;109(3):273–283.</ref><ref>Lewis MJ, Young TW. ''Brewing.'' Springer; 2001:216.</ref> Small starch granules, β-glucans, and pentosans, which in turn are linked to proteins, also take part in the formation of complexes, which lead to increased dough formation. They can also hinder the release of starch granules and thus the effect of the amylases. The formation of gel-protein is minimal at low temperature (e.g. 118°F, 48°C) possibly due to the action of proteases, but during and after the saccharification rests (e.g. 145°F, 63°C), the amount of gel-protein rises rapidly when the mash is oxidized. The ''Oberteig'' tends to become especially prominent if the mash is recirculated, or it can also form during vorlauf.
 All of these negative effects can be prevented by limiting oxygen in the mash, especially when oxygen-scavengers are also used.<ref name=poyri/><ref name=karhan/><ref name=mullerr/> In other words, [[low oxygen brewing]] improves lautering and recirculation speed due to the prevention of ''Oberteig'' and gel protein aggregate formation. However, low-oxygen mashing actually encourages effective coagulation of larger proteins such that they do not contribute to haze.<ref name=derouck>De Rouck G, Jaskula-Goiris B, De Causmaecker B, et al. [https://www.brewingscience.de/index.php?tpl=table_of_contents&year=2013&edition=0001%252F0002&article=82374 The impact of wort production on the flavour quality and stability of pale lager beer.] ''BrewingScience.'' 2013;66(1/2):1–11.</ref><ref name=karhan/> They are retained in the spent grains after lautering, but not in a form that reduces wort flow.