Enzymes: Difference between revisions

Line 17:

** '''Cytase''' degrades cell wall structures.<ref name=fix/>

===Mashing===

=== Mashing ===

During [[mashing]], a very large number of enzymes act simultaneously on the components of the grist under conditions that are far from optimal for many of them in terms of substrate concentration and accessibility, pH, and enzyme stability. Enzymes are progressively inactivated at different rates depending on the temperature, the pH, the presence of substrate and other substances (such as tannins and cofactors such as calcium ions) in solution.<ref name=bsp/> Starch, proteins, nucleic acids, lipids and other substances are degraded, usually by hydrolytic (cleaving) reactions, but other reactions, such as oxidations, also occur.<ref>Szwajgier D. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2011.tb00505.x Dry and wet milling of malt. A preliminary study comparing fermentable sugar, total protein, total phenolics and the ferulic acid content in non-hopped worts.] ''J Inst Brew.'' 2011;117(4):569–577.</ref>

Line 52:

* Phenolic compound release or oxidation (see [[Phenolic compounds]], [[Oxidation]])

** '''Polyphenol oxidase''' (optimal 60–65°C, pH 6.5–7.0) oxidizes polyphenols, especially lower molecular weight polyphenols (e.g. catechin).<ref name=esslinger/><ref name=quibai>Quinde-Axtell Z, Baik BK. [https://pubs.acs.org/doi/abs/10.1021/jf060974w Phenolic compounds of barley grain and their implication in food product discoloration.] ''J Agric Food Chem.'' 2006;54(26):9978–9984.</ref><ref name=quipow>Quinde-Axtell Z, Powers J. Baik BK. [https://onlinelibrary.wiley.com/doi/abs/10.1094/CC-83-0385 Retardation of discoloration in barley flour gel and dough.] ''Cereal Chem.'' 2006;83(4):385–390.</ref><ref name=adb/> Polyphenol oxidase loses activity during malting, being largely destroyed by kilning (although still active in pils malt), and it may be entirely destroyed depending on the temperature (even in pale malt).<ref name=clalar/> Polyphenol oxidase is able to catalyze the oxidation of polyphenol compounds with oxygen into very reactive quinonic compounds.<ref name=cargon/> Polyphenol oxidase is the main responsible for the enzymatic browning in fruits and vegetables.<ref name=cargon/>

** '''Polyphenol oxidase''' (optimal 60–65°C, pH 6.5–7.0) oxidizes polyphenols, especially lower molecular weight polyphenols (e.g. catechin).<ref name=esslinger/><ref name=quibai>Quinde-Axtell Z, Baik BK. [https://pubs.acs.org/doi/abs/10.1021/jf060974w Phenolic compounds of barley grain and their implication in food product discoloration.] ''J Agric Food Chem.'' 2006;54(26):9978–9984.</ref><ref name=quipow>Quinde-Axtell Z, Powers J. Baik BK. [https://onlinelibrary.wiley.com/doi/abs/10.1094/CC-83-0385 Retardation of discoloration in barley flour gel and dough.] ''Cereal Chem.'' 2006;83(4):385–390.</ref><ref name=adb/> Polyphenol oxidase loses activity during malting, being largely destroyed by kilning (although still active in pils malt), and it may be entirely destroyed depending on the temperature (even in pale malt).<ref name=clalar/> Polyphenol oxidase is able to catalyze the oxidation of polyphenol compounds with oxygen into very reactive quinonic compounds.<ref name=cargon/> Polyphenol oxidase is the main responsible for the enzymatic browning in fruits and vegetables.<ref name=cargon/> PPO is totally destroyed during malting.<ref name=bilgar>Billaud C, Garcia R, Kohler B, Néron S, Boivin P, Nicolas J. [https://www.vttresearch.com/sites/default/files/pdf/symposiums/2000/S207.pdf#page=248 Possible implications of four oxidoreductases (polyphenoloxidase, catalase, lipoxygenase, and peroxidase) present in brewery's barley and malt on organoleptic and rheological properties of mash and beer.] In: VTT SYMPOSIUM 2000;207:247–250.</ref>

** '''Feruloyl esterase''' AKA '''ferulic acid esterase''' AKA '''cinnamoyl esterase''' (optimal activity 40–50°C, pH 5.2–6.6) liberates phenolic acids (mainly [[ferulic acid]]) from [[beta-glucans and arabinoxylans|arabinoxylans]].<ref name=adb/><ref name=schwarz>Schwarz KJ, Boitz LI, Methner FJ. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2012-1011-02 Release of phenolic acids and amino acids during mashing dependent on temperature, pH, time, and raw materials.] ''J Am Soc Brew Chem.'' 2012;70(4):290–295.</ref> Inactive at 65°C and above.<ref name=wangas>Wannenmacher J, Gastl M, Becker T. [https://ift.onlinelibrary.wiley.com/doi/abs/10.1111/1541-4337.12352 Phenolic substances in beer: Structural diversity, reactive potential and relevance for brewing process and beer quality.] ''Compr Rev Food Sci Food Saf.'' 2018;17(4):953–988.</ref>

** '''β(1-4)-endoxylanase''' releases xylooligosaccharides<ref name=schwarz/>