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Enzymes: Difference between revisions
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** '''Catalase''' catalyses the conversion of peroxides to water and ground state (unreactive) oxygen, however it is rapidly destroyed during mashing at 149°F (65°C) and therefore it is largely irrelevant in the brewhouse.<ref name=etokakpan/> inactivated rapidly during mashing at 65°C.<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> catalase - inactivated rapidly during mashing at 65°C.<ref name=poyri/> Catalase is denatured during mashing at 65C.<ref name=clalar/> 2H<sub>2</sub>O<sub>2</sub> --> 2 H<sub>2</sub>O + O<sub>2</sub> | ** '''Catalase''' catalyses the conversion of peroxides to water and ground state (unreactive) oxygen, however it is rapidly destroyed during mashing at 149°F (65°C) and therefore it is largely irrelevant in the brewhouse.<ref name=etokakpan/> inactivated rapidly during mashing at 65°C.<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> catalase - inactivated rapidly during mashing at 65°C.<ref name=poyri/> Catalase is denatured during mashing at 65C.<ref name=clalar/> 2H<sub>2</sub>O<sub>2</sub> --> 2 H<sub>2</sub>O + O<sub>2</sub> | ||
** '''Superoxide dismutase''' catalyses the formation of peroxides from superoxides which in the absence of catalase leads to the formation of the hydroxyl radical.<ref name=etokakpan>EtokAkpan OU. [https://link.springer.com/article/10.1023/B:WIBI.0000043169.65135.b4 Preliminary study of fat oxidation in sorghum and maize brewing.] ''World J Microbiol Biotechnol.'' 2004;20:569–573.</ref> inactivated rapidly during mashing at 65°C.<ref name=poyri/> superoxide dismutase - inactivated rapidly during mashing at 65°C.<ref name=poyri/> SOD is destroyed within 15 minutes of mashing at 65C.<ref name=clalar/> 2O<sub>2</sub><sup>-</sup> + 2H<sup>+</sup> --> O<sub>2</sub> + H<sub>2</sub>O<sub>2</sub> | ** '''Superoxide dismutase''' catalyses the formation of peroxides from superoxides which in the absence of catalase leads to the formation of the hydroxyl radical.<ref name=etokakpan>EtokAkpan OU. [https://link.springer.com/article/10.1023/B:WIBI.0000043169.65135.b4 Preliminary study of fat oxidation in sorghum and maize brewing.] ''World J Microbiol Biotechnol.'' 2004;20:569–573.</ref> inactivated rapidly during mashing at 65°C.<ref name=poyri/> superoxide dismutase - inactivated rapidly during mashing at 65°C.<ref name=poyri/> SOD is destroyed within 15 minutes of mashing at 65C.<ref name=clalar/> 2O<sub>2</sub><sup>-</sup> + 2H<sup>+</sup> --> O<sub>2</sub> + H<sub>2</sub>O<sub>2</sub> | ||
** '''Oxalate oxidase''' Active during mashing<ref name=kanbam2/> | ** '''Oxalate oxidase''' (AKA germin) - catalyses the conversion of oxalate into carbon dioxide and hydrogen peroxide. pH optimum of approximately 4.0 but active over a large range. Because the enzyme is active in a broad pH range, and because it has high heat tolerance, it was active during mashing, but it was less important than other oxidases for scavenging oxygen from mashes because of its low affinity for oxygen.<ref name=kanoxi/> Active during mashing<ref name=kanbam2/> | ||
** '''Ascorbate (per)oxidase''' (optimal pH 5.5) - catalyzes the oxidation of [[ascorbic acid]] by hydrogen peroxide.<ref name=kanoxi>Kanauchi M. [https://www.intechopen.com/chapters/56077 Oxidative enzyme effects in malt for brewing.] In: Kanauchi M, ed. ''Brewing Technology.'' IntechOpen. 2017:29–47.</ref> Highly active during mashing.<ref name=kanbam2/> | ** '''Ascorbate (per)oxidase''' (optimal pH 5.5) - catalyzes the oxidation of [[ascorbic acid]] by hydrogen peroxide.<ref name=kanoxi>Kanauchi M. [https://www.intechopen.com/chapters/56077 Oxidative enzyme effects in malt for brewing.] In: Kanauchi M, ed. ''Brewing Technology.'' IntechOpen. 2017:29–47.</ref> Highly active during mashing.<ref name=kanbam2/> | ||
** '''Ascorbic acid oxidase''' (optimal pH 7.0, but active in a large range) - catalyzes the oxidation of ascorbic acid by O<sub>2</sub>.<ref name=kanoxi/> | ** '''Ascorbic acid oxidase''' (optimal pH 7.0, but active in a large range) - catalyzes the oxidation of ascorbic acid by O<sub>2</sub>.<ref name=kanoxi/> | ||