Protein: Difference between revisions

Oxygen introduced into the mash causes the formation of larger polypeptide aggregates (linked via disulfide bridges, see below), which become insoluble at higher mash temperatures and which settle as a doughy layer on top of the spent grains in a traditional lauter tun.<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/> This layer is often called the ''Oberteig'' (which means "upper dough" in German), and it can prevent clarification, and slow down or stop lautering and/or recirculation. Similar behavior is seen by the so-called "gel proteins", which are certain types of hordeins dissolved during malting. During mashing, they too can result in groups of a protein/polypeptide/lipid aggregates resulting from oxidation. 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.