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Protein: Difference between revisions
→Proteins in the mash
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==Proteins in the mash== | ==Proteins in the mash== | ||
Complex protein biochemistry occurs during the mash.<ref name=kerr/> The activity of enzymes is the prime example, and they have numerous important effects (see [[Enzymes]]). Beyond this, certain proteins combine with other substances such as sugars or [[phenolic compounds|polyphenols]], storage proteins are partly degraded and/or solubilized and transferred into the produced wort, and some proteins can help buffer against [[oxidation]].<ref name=steiner/> Negative effects on the brewing process can also occur as a result of protein chemistry. The protein matrix (hordeins) of poorly-modified [[malt]] may inhibit [[saccharification|starch degradation]] during mashing by physically preventing access by α-amylase, which can potentially reduce the amount of [[extract]] obtained.<ref name=yu/> Protein aggregation may reduce or prevent wort flow during [[lautering]] or recirculation (i.e. a "[[stuck mash]]") by forming a gel.<ref name=slack>Slack PT, Baxter ED, Wainwright T. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1979.tb06837.x Inhibition by hordein of starch degradation.] ''J Inst Brew.'' 1979;85(2):112–114.</ref> Despite all this activity, much of the protein is insoluble and therefore discarded with the [[spent grains]]. The intact proteins present in the wort at the end of mashing (at least 20 different types) are generally those that are resistant to degradation by malt proteinases.<ref name=iimure/> Proteins are not significantly modified via [[glycoproteins|glycation]] during the mashing process. However, mashing at higher temperature increases the level of [[glycoproteins]], perhaps due to greater extraction.<ref name=jegou/> | Complex protein biochemistry occurs during the mash.<ref name=kerr/> The activity of enzymes is the prime example, and they have numerous important effects (see [[Enzymes]]). Beyond this, certain proteins combine with other substances such as sugars or [[phenolic compounds|polyphenols]], storage proteins are partly degraded and/or solubilized and transferred into the produced wort, and some proteins can help buffer against [[oxidation]].<ref name=steiner/> Negative effects on the brewing process can also occur as a result of protein chemistry. The protein matrix (hordeins) of poorly-modified [[malt]] may inhibit [[saccharification|starch degradation]] during mashing by physically preventing access by α-amylase, which can potentially reduce the amount of [[extract]] obtained.<ref name=yu/> Protein aggregation may reduce or prevent wort flow during [[lautering]] or recirculation (i.e. a "[[stuck mash]]") by forming a gel.<ref name=slack>Slack PT, Baxter ED, Wainwright T. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1979.tb06837.x Inhibition by hordein of starch degradation.] ''J Inst Brew.'' 1979;85(2):112–114.</ref> Despite all this activity, much of the protein is insoluble and therefore discarded with the [[spent grains]]. The intact proteins present in the wort at the end of mashing (at least 20 different types) are generally those that are resistant to degradation by malt proteinases.<ref name=iimure/> Proteins are not significantly modified via [[glycoproteins|glycation]] during the mashing process. However, mashing at higher temperature increases the level of [[glycoproteins]], perhaps due to greater extraction.<ref name=jegou/> | ||
The precipitation of nitrogenous compounds at high temperatures removes sequestering agents from the wort leading to a significant loss of minerals.<ref name=monmay>Montanari L, Mayer H, Marconi O, Fantozzi P. [https://www.sciencedirect.com/science/article/abs/pii/B9780123738912000341 Chapter 34: Minerals in beer.] In: Preedy VR, ed. [[Library|''Beer in Health and Disease Prevention.'']] Academic Press; 2009:359–365.</ref> | |||
===Oxidation=== | ===Oxidation=== | ||