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Enzymes: Difference between revisions
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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. 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> | 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. | '''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. | '''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. | ||
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** '''Cytase''' degrades cell wall structures.<ref name=fix/> | ** '''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> | 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> | ||
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** '''Invertase''' (optimal 50°C, pH 5.5) splits sucrose into glucose and fructose. Active up to 62–67°C.<ref name=adb/> | ** '''Invertase''' (optimal 50°C, pH 5.5) splits sucrose into glucose and fructose. Active up to 62–67°C.<ref name=adb/> | ||
* Protein degradation (see [[Protein]]) | * 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. | ** '''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/> | ** '''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. | ** '''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. | ** '''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]]) | * Beta-glucan liberation and degradation (see [[Beta-glucans and arabinoxylans]]) | ||
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* Lipid degradation and oxidation (see [[Lipids]]) | * 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> | ** '''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/> | ** '''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/> | ** '''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]]) | * 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> | ** '''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> | ** '''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(1-4)-endoxylanase''' releases xylooligosaccharides<ref name=schwarz/> | ||
** '''β-D-xylosidase''' releases xylose and xylooligosaccharides<ref name=schwarz/> | ** '''β-D-xylosidase''' releases xylose and xylooligosaccharides<ref name=schwarz/> | ||
** '''α-L-arabinofuranosidase''' releases the corresponding furanosidase<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> | |||
** '''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> | |||
* Other | * Other | ||
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** '''Pentosan solubilase''' releases bound 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/> | ** '''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''' 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''' 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=== | ===Fermentation=== | ||
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**'''Phenylacrylic acid decarboxylase (PAD1)''' is not actually a decarboxylase, but catalyzes the synthesis of an FMN-related co-factor required for the function of FDC1<ref name=len/> | **'''Phenylacrylic acid decarboxylase (PAD1)''' is not actually a decarboxylase, but catalyzes the synthesis of an FMN-related co-factor required for the function of FDC1<ref name=len/> | ||
**'''Ferulic acid decarboxylase (FDC1)''' catalyzes the decarboxylation of cinnamic acid and derivatives.<ref name=len/> | **'''Ferulic acid decarboxylase (FDC1)''' catalyzes the decarboxylation of cinnamic acid and derivatives.<ref name=len/> | ||
==Added enzymes== | ==Added enzymes== | ||
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Potential sources | Potential sources | ||
*http:// | *http://themodernbrewhouse.com/forum/viewtopic.php?f=11&t=1821 | ||
*[http://www. | *[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://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 | *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://www.knudsenbeverageconsulting.com/wp-content/uploads/2011/mbaa/mbaarmdpresentationenzymesinbrewing51102.pdf | ||
*http://themodernbrewhouse.com/forum/viewtopic.php?f=11&t=2168 | *http://themodernbrewhouse.com/forum/viewtopic.php?f=11&t=2168 | ||