Editing Enzymes

{{In progress}}

An enzyme is a [[protein]] that catalyzes a chemical reaction, greatly speeding it up while not being consumed by the reaction. This allows enzymes to be active even in very low concentrations. Enzymes play an important role in the creation of all fermented beverages, and more generally, they are needed for all life processes.<ref name=kunzemashing/> As with all proteins, enzymes have particular temperature and pH ranges in which they function, and more narrow ranges in which the activity is considered optimal.<ref name=mostra>Mosher M, Trantham K. [[library|''Brewing Science: A Multidisciplinary Approach.'']] 2nd ed. Springer; 2021.</ref> The effect of temperature is greater than the effect of pH. Knowing the optimal ranges can be helpful, but it must be realized that the enzymes will be active to some extent outside those ranges.<ref name=bsp/> Enzymes denature (the three-dimensional structure unfolds) at higher temperatures, rendering them inactive.<ref name=kunzemashing/> Enzymes tend to have a very specific substrate upon which they act, and therefore are often named after the substrate, adding "-ase" to the end.<ref name=fix>Fix G. [[Library|''Principles of Brewing Science.'']] 2nd ed. Brewers Publications; 1999.</ref>

'''Coenzymes''': The action of many enzymes is tied to the presence of an additional non-protein component that binds with its structure. For example, bivalent metal ions (e.g. iron, magnesium, calcium) are often involved as coenzymes.<ref>Kunze, Wolfgang. ''Technology Brewing & Malting.'' Edited by Olaf Hendel, 6th English Ed., VLB Berlin, 2019. p. 54.</ref>

'''Isoenzymes''': Enzymes that have different structures but catalyze the same reaction are called isoenzymes. Each isoenzyme may have different characteristics such as optimal temperature and pH ranges. Generally, most enzymes in living organisms have several isoenzymes.

==Natural enzymes==
===Malting===
''Coming eventually''

Enzymes are of special importance during malting. In post-harvest maturity, harvested malting barley contains a huge amount of enzymes and their precursors. From the malting point of view, enzymes of the hydrolasis group can be classified as the most important enzymes. They can be divided into four groups (cytolytic enzymes, proteolytic enzymes, phosphatases, amylases) and the class of oxidoreductases, followed then by transferases, lyases, isomerases, and ligases.<ref>Benešová K, Běláková S, Mikulíková R, Svoboda Z. [http://kvasnyprumysl.eu/index.php/kp/article/download/95/74 Activity of proteolytic enzymes during malting and brewing.] ''Kvasný Prům.'' 2017;63(1):2–7.</ref>

*Cytolytic enzymes
** '''Beta-glucanase''' degrades cell wall structures.<ref name=fix/>
** '''Cytase''' degrades cell wall structures.<ref name=fix/>

=== 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>

* Starch and sugar degradation (see [[Starch]] and [[Sugars]])
** '''α-amylase''' (optimal 72–75°C, pH 5.6–5.8) degrades starch and dextrins into smaller sugars by cleaving α-1,4-bonds.<ref name=esslinger>Krottenthaler M, Back W, Zarnkow M. Wort production. In: Esslinger HM, ed. [[Library|''Handbook of Brewing: Processes, Technology, Markets.'']] Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA; 2009.</ref><ref name=adb/><ref name=kunzemashing/><ref name=bsp/> Rapid inactivation occurs at 78–80°C and above.<ref name=visser>Visser MJ. [https://core.ac.uk/download/pdf/37326474.pdf Evaluation of malted barley with different degrees of fermentability using the Rapid Visco Analyser (RVA).] University of Stellenbosch. 2011.</ref><ref name=adb/>
** '''β-amylase''' (optimal 60–65°C, pH 5.4–5.6) releases maltose from the ends of sugar chains by cleaving α-1,4-bonds.<ref name=esslinger/><ref name=adb>Narziss L, Back W, Gastl M, Zarnkow M. [[Library|''Abriss der Bierbrauerei.'']] 8th ed. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA; 2017.</ref><ref name=kunzemashing/> Rapid inactivation occurs at temperatures of 65-70°C and above.<ref name=visser/><ref name=adb/><ref name=evans>Evans DE, Fox GP. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2017-4707-01 Comparison of diastatic power enzyme release and persistence during modified Institute of Brewing 65°C and Congress programmed mashes]. ''J Am Soc Brew Chem.'' 2017;75(4):302–311.</ref>
** '''Limit dextrinase''' AKA '''debranching enzyme''' AKA '''R-enzyme''' AKA '''pullulanase''' (optimal 55–65°C, pH 5.4) degrades limit dextrins into dextrins/sugars by cleaving the branch point (α-1,6 bonds).<ref name=esslinger/><ref name=adb/><ref>McCafferty CA,  Jenkinson HR, Brosnan JM, Bryce JH. [https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2050-0416.2004.tb00623.x Limit dextrinase — Does its malt activity relate to its activity during brewing?] ''J Inst Brew.'' 2004;110(4):284–296.</ref> Inactivation occurs at temperatures of 65-75°C and above, although it's not destroyed unless boiled.<ref name=visser/><ref name=adb/><ref name=evans/>
** '''α-glucosidase''' AKA '''maltase''' (optimum 35–45°C, pH 4.6–6.0) degrades maltose, isomaltose, oligosaccharides, dextrins and starch, cleaving single glucose units from the ends of chains (mainly α-1,4 bonds, but also some α-1,6 bonds).<ref name=bsp/><ref name=esslinger/><ref name=guerra>Guerra NP, Torrado-Agrasar A, López-Macías C, et al. Use of Amylolytic Enzymes in Brewing. In: Preedy VR, ed. ''Beer in Health and Disease Prevention.'' Academic Press; 2009:113–126.</ref><ref name=crit>Bamforth CW, Fox GP. Critical aspects of starch in brewing. ''BrewingScience.'' 2020;73:126–139.</ref><ref>Im H, Henson CA. [https://www.sciencedirect.com/science/article/abs/pii/000862159500212C Characterization of high pI α-glucosidase from germinated barley seeds: substrate specificity, subsite affinities and active-site residues.] ''Carbohydr Res.'' 1995;277(1):145–159.</ref> This class of enzyme has not been studied to the same extent as the other starch-degrading enzymes.<ref>Andriotis VME, Saalbach G, Waugh R,
Field RA, Smith AM. [https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0151642 The Maltase Involved in Starch Metabolism in Barley Endosperm Is Encoded by a Single Gene.] ''PLoS ONE.'' 2016;11(3):1–13</ref>
** '''Glucoamylase''' (optimal 35–40°C) cleaves a single glucose unit from the end of any sugar chain (both α-1,4 and α-1,6 bonds).<ref name=Vriesekoop>Vriesekoop F, Rathband A, MacKinlay J, Bryce JH. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2010.tb00425.x The evolution of dextrins during the mashing and fermentation of all-malt whisky production.] ''J Inst Brew.'' 2010;116(3):230–238.</ref><ref name=guerra/> Its activity is virtually non-existent during mashing because of its very low optimal temperature.
** '''Invertase''' (optimal 50°C, pH 5.5) splits sucrose into glucose and fructose. Active up to 62–67°C.<ref name=adb/>

* Protein degradation and oxidation (see [[Protein]])
** '''Endopeptidases''', which include '''metalloproteases''', '''cysteine proteases''', '''aspartic proteases''', and '''serine proteases''' (optimal 45–50°C, pH 3.9–5.5) over 40 different endopeptidase enzymes degrade proteins into peptides and free amino acids.<ref name=esslinger/><ref name=kunzemashing>Kunze W. Wort production. In: Hendel O, ed. [[Library|''Technology Brewing & Malting.'']] 6th ed. VLB Berlin; 2019. p. 230.</ref>
** '''Carboxypeptidases''' (optimal 50°C, pH 4.8–5.6) degrade proteins & peptides into free amino acids.<ref name=esslinger/><ref name=kunzemashing/>
** '''Aminopeptidases''' (optimal 45°C, pH 7.0–7.2) degrade proteins & peptides into free amino acids.<ref name=esslinger/><ref name=kunzemashing/> Inactive during mashing.
** '''Dipeptidase''' (optimal 45°C, pH 8.8) degrades dipeptides into free amino acids.<ref name=esslinger/><ref name=kunzemashing/> Inactive during mashing.
** '''Thiol oxidase''' (optimal pH 8.0) catalyzes oxidation of thiols. Very active during mashing.<ref name=kanbam2>Kanauchi M, Bamforth CW. [https://www.themodernbrewhouse.com/wp-content/uploads/2019/02/BrewingScience_bamforth_82-84.pdf A Challenge in the study of flavour instability.] ''BrewingScience - Monatsschrift Brauwiss.'' 2018;71(Sept/Oct):82–84.</ref>

* Beta-glucan liberation and degradation (see [[Beta-glucans and arabinoxylans]])
** '''β-glucan solubilase''' (optimal 62–65°C, pH 6.8) releases high-molecular-weight matrix-bound β-glucans, increasing the amount in the wort.<ref name=esslinger/><ref name=sacher2/>
** '''Endo-(1,3;1,4)-β-glucanase''' (optimal 48°C, pH 4.7) degrades soluble high-molecular-weight β-glucan into low-molecular-weight β-glucan.<ref name=esslinger/><ref name=jin>Jin YL, Speers RA, Paulson AT, Stewart RJ. [https://www.researchgate.net/profile/Robert-Speers/publication/296811873_Barley_b-glucans_and_their_degradation_during_malting_and_brewing/links/595a4f16458515a5406fc54e/Barley-b-glucans-and-their-degradation-during-malting-and-brewing.pdf Barley β-glucans and their degradation during malting and brewing.] ''Tech Q Master Brew Assoc Am.'' 2004;41(3):231–240.</ref>
** '''Endo-(1,3)-β-glucanase''' degrades soluble high-molecular-weight β-glucan into low-molecular-weight β-glucan, and may also help solubilize β-glucan.<ref name=muller>Muller R. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-53-0136 Factors influencing the stability of barley malt β-glucanase during mashing.] ''J Am Soc Brew Chem.'' 1995;53(3):136–140.</ref><ref name=kanbam>Kanauchi M, Bamforth CW. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2008.tb00332.x The relevance of different enzymes for the hydrolysis of β-glucans in malting and mashing.] ''J Inst Brew.'' 2008;114(3);224–229.</ref>
** '''Endo-(1,4)-β-glucanase''' AKA '''cellulase''' degrades soluble high-molecular-weight β-glucan (including [[cellulose]]) into low-molecular-weight β-glucan.<ref name=muller/><ref name=kanbam/><ref name=mashing/>
** '''Exo-β-glucanase''' (optimal <40°C pH 4.5) degrades glucose from the ends of β-glucan.<ref name=esslinger/><ref name=kanbam/>

* Phosphate liberation (see [[Phosphates]])
** '''Phosphatases''' (optimal 50–53°C, pH 5.0) releases organic-bound phosphate, increasing inorganic phosphate in the wort.<ref name=esslinger/><ref name=sacher2>Sacher B, Becker T, Narziss L. [http://www.themodernbrewhouse.com/wp-content/uploads/2017/04/pddvxvf.pdf Some reflections on mashing – Part 2.] ''Brauwelt International.'' 2016;6:392-397.</ref> Inactive at 62°C.<ref name=sacher2/>

* Lipid degradation and oxidation (see [[Lipids]])
** '''Lipase''' (optimal 55–65°C, pH 6.8–7.0) degrades lipids & lipid hydroperoxides into glycerine plus free fatty acids, and/or hydroperoxides.<ref name=esslinger/><ref name=golston>Golston AM. The impact of barley lipids on the brewing process and final beer quality: A mini-review. ''Tech Q Master Brew Assoc Am.'' 2021;58(1):43–51.</ref><ref name=schwarzp>Schwarz P, Stanley P, Solberg S. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-60-0107 Activity of lipase during mashing.] ''J Am Soc Brew Chem.'' 2002;60(3):107–109.</ref><ref name=mashing>Evans E. [[Library|''Mashing.'']]  American Society of Brewing Chemists and Master Brewers Association of the Americas; 2021.</ref>
** '''Lipoxygenases''' (optimal 45–55°C, pH 6.3–7.0) oxidizes fatty acids into fatty acids hydroperoxides.<ref name=esslinger/><ref name=golston/><ref name=mashing/> The function of lipoxygenase (LOX) during mashing is rather controversial. Lipoxygenase is suggested to be heat labile because only a minor part of the activity present in green malt survives kilning. However, this remaining part of LOX is known to be very stable towards heating. Almost 60% of the LOX activity of malt extract can survive for 1 h at a temperature of 67°C. LOX may survive temperatures as high as 95°C in spent grains. In addition, lipoxygenase purified from germinating barley has a pH optimum at 6.5.<ref name=poyri/>
** '''Hydroperoxide lyase''' transforms lipid hydroperoxides through a series of steps into staling compounds such as trans-2-nonenal.<ref name=mashing/>

* 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>Clarkson SP, Large SJ, Bamforth CW. [https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2050-0416.1992.tb01096.x Oxygen-scavenging enzymes in barley and malt and their effects during mashing.] ''J Inst Brew.'' 1992;98(2):111–115.</ref> Polyphenol oxidase is able to catalyze the oxidation of polyphenol compounds with oxygen into very reactive quinonic compounds.<ref name=cargon>Carvalho DO, Gonçalves LM, Guido LF. [https://ift.onlinelibrary.wiley.com/doi/abs/10.1111/1541-4337.12218 Overall antioxidant properties of malt and how they are influenced by the individual constituents of barley and the malting process.] ''Compr Rev Food Sci Food Saf.'' 2016;15(5):927–943.</ref> 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://web.archive.org/web/20221204060251/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/>
** '''β-D-xylosidase''' releases xylose and xylooligosaccharides<ref name=schwarz/>
** '''α-L-arabinofuranosidase''' releases the corresponding furanosidase<ref name=schwarz/>
** '''Peroxidase''' (optimal >60°C, pH 6.2) generates free radicals from various organic and inorganic substrates.<ref name=esslinger>Krottenthaler M, Back W, Zarnkow M. Wort production. In: Esslinger HM, ed. [[Library|''Handbook of Brewing: Processes, Technology, Markets.'']] Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA; 2009.</ref> Requires [[iron]] coenzyme.<ref name=bsp/> Peroxidase can retain its activity even at 80°C.<ref name=poyri/> Peroxidases catalyze the oxidation of polyphenols.<ref name=adb/> Barley malt contains remarkably high activity of the many peroxidase iso-enzymes, giving evidence for the importance of hydrogen peroxide reactions.<ref name=muller95>Muller R. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1997.tb00961.x The formation of hydrogen peroxide during oxidation of thiol-containing proteins.] ''J Inst Brew.'' 1997;103(5):307–310.</ref> Peroxidases are considered to act mostly on the oxidation of polyphenols.<ref name=poyri/> Many different peroxidases exist and vary by the variety of barley.<ref name=mahalingam>Mahalingam R. [https://bmcgenomics.biomedcentral.com/articles/10.1186/s12864-016-3408-5 Shotgun proteomics of the barley seed proteome.] ''BMC Genomics.'' 2017;18(44).</ref>

* Other
** '''Endo-xylanase''', '''exo-xylanase''', and '''arabinosidases''' (optimal 45°C) degrade [[pentosans]].<ref name=adb/>
** '''Pentosan solubilase''' releases bound pentosans.<ref name=adb/>
** '''Phosphorylase''' cleaves the terminal alpha-(1, 4) links in non-reducing chain ends with inorganic phosphate to release glucose-1-phosphate. Apparently its possible role in mashing has never been investigated.<ref name=bsp/>
** '''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>
** '''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/>
** '''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/>

===Fermentation===
''Coming eventually''
* Yeast enzymes
** '''Invertase''' breaks sucrose into its constituents glucose and fructose.
** '''Phenolic acid decarboxylase (PAD; also known as ferulic acid decarboxylase, courmaric acid decarboxylase, cinnamate decarboxylase)''' catalyzes the enzymatic decarboxylation of HCAs to their vinyl derivatives. PAD is present in a wide variety of bacteria and fungi. These include species which represent contaminants in a brewing environment, but also species and strains utilized in brewing, such as many strains of brewer's yeast (''Saccharomyces cerevisiae''), as well as ''Brettanomyces'' sp., ''Lactobacillus'', and ''Pediococcus''.<ref name=len>Lentz M. [https://www.mdpi.com/2311-5637/4/1/20 The impact of simple phenolic compounds on beer aroma and flavor.] ''Fermentation.'' 2018;4(1):20.</ref>

==Added enzymes==
A variety of enzyme products ("exogenous" enzymes) are available to home brewers for various purposes such as increasing starch/dextrin degradation or decreasing haze.

General information:

'''Storage''' - Enzyme preparations are not stable, so they should be stored cool and used fresh since the activity decreases over time.<ref name=bsp/><ref name=hob10/> Refer to the manufacturer for specific recommendations.

'''Impurities''' - Enzyme products are created by living organisms.<ref name=mashing/> Therefore these products are not "pure", and will usually contain other substances such as residual materials from the nutrient medium in which the microbes were cultured, other enzymes besides the one(s) specified, diluents, extenders or carriers, and preservatives. Be aware that these impurities can potentially lead to haze formation, deterioration of beer foam, and loss of yeast flocculation. Modern enzyme products usually do NOT contain viable microbes.<ref name=bsp/><ref name=hob10>Ryder DS. Processing aids in brewing. In: Stewart GG, Russell I, Anstruther A, eds. [[Library|''Handbook of Brewing.'']] 3rd ed. CRC Press; 2017.</ref>

'''Product comparison''' - Products from different suppliers should be considered distinct, and it can be difficult to make comparisons between them due to lack of standardization. Also, the action of enzyme products can be greatly influenced by the usage conditions (e.g. temperature and pH), and therefore the results may vary between different brews. Consequently, the effectiveness of the addition of an enzyme preparation must be determined by brewers under their particular processing conditions.<ref name=bsp>Briggs DE, Boulton CA, Brookes PA, Stevens R. [[Library|''Brewing Science and Practice.'']] Woodhead Publishing Limited and CRC Press LLC; 2004.</ref>

Common products:
* '''Amylase''' (bacterial) - Degrades starch to dextrins very effectively but does not produce much fermentable sugar. Used mainly for [[saccharification|liquefaction]] of [[adjuncts|adjunct]] starch.<ref name=hob10/> See [[Bacterial alpha amylase]].
* '''Fungal Alpha Amylase''' - Degrades larger dextrins, producing limit dextrins plus some fermentable sugars. Used to mildly increase fermentability. See [[Fungal alpha amylase]].
* '''Glucoamylase''' - Degrades dextrins to produce mostly glucose, greatly increasing fermentability. Used to produce dry beer (e.g. "Brut IPA"), low-carb beer, or to accelerate [[sour beer]] production. See [[Glucoamylase]].

[[File:Amylase-comparison-chart.jpg|600px]]

* '''Clarity Ferm''' AKA '''Clearzyme''' AKA Clarex? is a proline-specific endoprotease that reduces chill haze and reduces "gluten"<ref name=mashing/>
* '''Glucabuster'''
* '''Lysovin''' (lysozyme)
* Alpha galactosidase [https://www.homebrewing.org/Alpha-Galactosidase-Enzyme-3-Pack_p_8270.html from AIH]

*ferulic acid esterase products - can be used to increase release of phenolic acids during mashing<ref>https://onlinelibrary.wiley.com/doi/epdf/10.1002/j.2050-0416.2011.tb00489.x</ref>

<!-- Enzymes that may be difficult to acquire and/or just aren't used by home brewers ...

Ondea Pro and Brewers Compass are enzyme concoctions that allow brewing satisfactory quality beer from unmalted barley.<ref name=mashing/>

Tested Shearzyme 500L (xylanase, Novozymes), Glucanase (Megazyme), Ultraflo Max (glucanase + xylanase, Novozymes) Neutrase 0.8L (proteinase, Novozymes): All exogenous enzymes gave, to different extents, increased activities of starch-degrading enzymes compared with the control to which no enzymes were added. Neutrase 0.8L proteinase was the most effective enzyme and the maximal activities of α-amylase, β-amylase and limit dextrinase during mashing were improved by 12, 57 and 173%, respectively, compared with the control.<ref>Hu S, Dong J, Fan W, et al. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/jib.172 The influence of proteolytic and cytolytic enzymes on starch degradation during mashing.] ''J Inst Brew.'' 2014;120(4):379–384.</ref> The β-glucanase, Shearzyme 500L, Ultraflo Max and Neutrase 0.8L enhanced the soluble starch content by 20, 14, 23 and 43% respectively, at the end of the
protease/β-glucanase rest, and improved the soluble starch by 20, 23, 20 and 28%, respectively, at 55 min into mashing (gel temp), compared with the control to which no enzyme was added.

The β-amylase of barley is also available commercially and can be used to increase attenuation. Barley β-amylase is relatively stable at acid pH, so it will partially digest dextrins under fermentation conditions.<ref name=hob10/>

Alpha-acetolactate decarboxylase (ALDC) can be used in fermentation or after the beer has been transferred to aging, maturation, or storage in order to eliminate alpha-acetolactate and, thus, the associated undesirable buttery flavor of diacetyl.<ref name=hob10/>

The heat-stable amylase from ''B. licheniformis'' is not very effective at temperatures below 70ºC. The enzyme is not recommended for use in a normal brewer’s malt mash, where the temperature cannot be above 70ºC because of the limited heat stability of barley β-amylase.<ref name=hob10>Ryder DS. Processing aids in brewing. In: Stewart GG, Russell I, Anstruther A, eds. [[Library|''Handbook of Brewing.'']] 3rd ed. CRC Press; 2017.</ref>

The value of using the bacterial enzyme pullulanase (similar to the debranching enzyme present in malt) in making highly fermentable worts is clear.<ref name=bsp/>

Pullulanase, a bacterial starch debranching enzyme that specifically hydrolyses (1→6)-a-glycosidic linkages, is effective in improving wort attenuation.<ref name=model>MacGregor AW, Bazin SL, Macri LJ, Babb JC. [https://www.sciencedirect.com/science/article/abs/pii/S0733521098902338 Modelling the contribution of ''alpha''-amylase, ''beta''-amylase and limit dextrinase to starch degradation during mashing.] ''J Cereal Sci.'' 1999;29(2):161–169.</ref> It increases maltose concentration rather than glucose. -->

==See also==
*[[Malting]]
*[[Mashing]]

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Potential sources
*http://themodernbrewhouse.com/forum/viewtopic.php?f=11&t=1821
*[http://www.themodernbrewhouse.com/wp-content/uploads/2017/04/BrewingScience_0910_James_2014.pdf Amino Acid Permeases and their Influence on Flavour Compounds in Beer]
*https://scholar.google.com/scholar?hl=en&as_sdt=1%2C36&q=sun+A+quantitative+assessment+of+the+importance+of+barley+seed+alpha-amylase%2C+beta-amylase%2C+debranching+enzyme+and+alpha-glucosidase+in+starch+degradation.&btnG=#d=gs_qabs&u=%23p%3DRr5Dbt7Zj7MJ
*https://www.researchgate.net/profile/Ahmed_Gomaa35/publication/323252887_Application_of_Enzymes_in_Brewing/links/5b5f33ae458515c4b2531f59/Application-of-Enzymes-in-Brewing.pdf
*http://www.knudsenbeverageconsulting.com/wp-content/uploads/2011/mbaa/mbaarmdpresentationenzymesinbrewing51102.pdf
*http://themodernbrewhouse.com/forum/viewtopic.php?f=11&t=2168
*https://www.themodernbrewhouse.com//forum/download/file.php?id=1931
*https://prowm.com/wp-content/uploads/2019/06/PRO-Tech-Notes-ISSUE-6-VOLUME-2.pdf
*https://www.researchgate.net/profile/Ahmed_Gomaa35/publication/323252887_Application_of_Enzymes_in_Brewing/links/5b5f33ae458515c4b2531f59/Application-of-Enzymes-in-Brewing.pdf
*Scheffler, A. and Bamforth, C.W. (2005) Exogenous β-glucanases and pentosanases and their impact on mashing, Enzym. Microb. Tech. 36, 813–817.
*Bamforth, C.W. (2010) The enzymology of cell wall breakdown during malting and mashing: An overview, Tech. Q. Mast. Brew. Assoc. Am.

==References==