Enzymes
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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.[1] 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.[2] Enzymes denature (the three-dimensional structure unfolds) at higher temperatures, rendering them inactive.[1] 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.[3]
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.
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
- Cytolytic enzymes
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.[2] Starch, proteins, nucleic acids, lipids and other substances are degraded, usually by hydrolytic (cleaving) reactions, but other reactions, such as oxidations, also occur.[4]
- Starch and sugar degradation (see Saccharification, Starch, 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.[5][6][1][2] Rapid inactivation occurs at 78–80°C and above.[7][6]
- 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.[5][6][1] Rapid inactivation occurs at temperatures of 65-70°C and above.[7][6][8]
- Limit dextrinase AKA debranching enzyme AKA R-enzyme (optimal 55–65°C, pH 5.4) degrades limit dextrins into dextrins/sugars by cleaving the branch point (α-1,6 bonds).[5][6][9] Inactivation occurs at temperatures of 65-75°C and above, although it's not destroyed unless boiled.[7][6][8]
- 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).[2][5][10][11][12] This class of enzyme has not been studied to the same extent as the other starch-degrading enzymes.[13]
- 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).[14][10] 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.[6]
- Protein degradation (see Protein)
- Endopeptidase (optimal 45–50°C, pH 3.9–5.5) degrades proteins into peptides and FAN.[5][1]
- Carboxypeptidase (optimal 50°C, pH 4.8–4.6) degrades proteins & peptides into FAN.[5][1]
- Aminopeptidase (optimal 45°C, pH 7.0–7.2) degrades proteins & peptides into FAN.[5][1]
- Dipeptidase (optimal 45°C, pH 8.8) degrades dipeptides into FAN.[5][1]
- Beta-glucan liberation and degradation (see Beta-glucans)
- β-glucan solubilase (optimal 62–65°C, pH 6.8) releases high-molecular-weight matrix-bound β-glucans, increasing the amount in the wort.[5][15]
- Endo-1,3-β-glucanase (optimal <60°C, pH 4.6) degrades soluble high-molecular-weight β-glucan into low-molecular-weight β-glucan, cellobiose, & laminaribiose.[5]
- Endo-1,4-β-glucanase (optimal 40–45°C pH 4.5–4.8) degrades soluble high-molecular-weight β-glucan into low-molecular-weight β-glucan, cellobiose, & laminaribiose.[5]
- Exo-β-glucanase (optimal <40°C pH 4.5) degrades cellobiose & laminaribiose into glucose.[5]
- Phosphate liberation (see Phosphates)
- Lipid degradation and oxidation (see Fatty acids, Oxidation)
- Phenolic compound oxidation (see Phenolic compounds, Oxidation)
- Polyphenol oxidase (optimal 60–65°C, pH 6.5–7.0) oxidizes polyphenols.[5]
- Non-specific oxidation (see Oxidation)
- Peroxidase (optimal >60°C, pH 6.2) generates free radicals from various organic and inorganic substrates.[5]
- Other
- Endo-xylanase, exo-xylanase, and arabinosidases (optimal 45°C) degrade pentosans.[6]
- Pentosan solubilase releases bound pentosans.[6]
- Feruloyl esterase (optimal 35-47°C, pH >5.7) dissolves the ester bond between ferulic acid and arabinose (see Pentosans and Phenolic compounds).[6]
- 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.[2]
Fermentation
Coming eventually
- Yeast enzymes
- Invertase breaks sucrose into its constituents glucose and fructose.
Wine
Coming eventually
Enzyme products
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.[2][16] Refer to the manufacturer for specific recommendations.
Impurities - Enzyme products are created by living organisms. 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.[2][16]
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.[2]
Common products:
- Amylase (bacterial) - Degrades starch to dextrins very effectively but does not produce much fermentable sugar. Used mainly for liquefaction of adjunct starch.[16]
- 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.
- Clarity Ferm AKA Clearzyme
- Glucabuster
- Lysovin (lysozyme)
See also
Potential sources
- http://lowoxygenbrewing.com/forum/viewtopic.php?f=11&t=1821
- "Enzymes in Brewing."
- "Limit dextrinase from malted barley: extraction, purification, and characterization"
- "Amylase action pattern on starch polymers"
- "The survival of limit dextrinase during fermentation in the production of Scotch whisky"
- "A new approach to limit dextrinase and its role in mashing."
- "Amino acid substitutions of the limit dextrinase gene in barley are associated with enzyme thermostability."
- https://www.researchgate.net/profile/David_Evan_Evans/publication/287854702_The_Impact_of_the_Thermostability_of_a-Amylase_b-Amylase_and_Limit_Dextrinase_on_Potential_Wort_Fermentability/links/578ebea708ae81b4466ecdc5.pdf
- https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/beta-amylase
- https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/alpha-amylase
- https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/enzymes
- Saranraj P. Fungal Amylase - A Review 2013.
- Amino Acid Permeases and their Influence on Flavour Compounds in Beer
- Osman AM. The advantage of using natural substrate-based methods in assessing the roles and synergistic and competitive interactions of barley malt starch-degrading enzymes. J Inst Brew. 2002;108:204–214.
- Muslin, E. H., Clark, S. E., and Henson, C. A. The effect of proline insertions on the thermostability of a barley α-glucosidase. Protein Eng. 15:29-33, 2002.
- 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
References
- ↑ a b c d e f g h Kunze W. Wort production. In: Hendel O, ed. Technology Brewing & Malting. 6th ed. VBL Berlin; 2019. p. 230.
- ↑ a b c d e f g h Briggs DE, Boulton CA, Brookes PA, Stevens R. Brewing Science and Practice. Woodhead Publishing Limited and CRC Press LLC; 2004.
- ↑ a b c Fix G. Principles of Brewing Science. 2nd ed. Brewers Publications; 1999.
- ↑ Szwajgier D. 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.
- ↑ a b c d e f g h i j k l m n o p q Krottenthaler M, Back W, Zarnkow M. Wort production. In: Esslinger HM, ed. Handbook of Brewing: Processes, Technology, Markets. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA; 2009.
- ↑ a b c d e f g h i j Narziss L, Back W, Gastl M, Zarnkow M. Abriss der Bierbrauerei. 8th ed. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA; 2017.
- ↑ a b c Visser MJ. Evaluation of malted barley with different degrees of fermentability using the Rapid Visco Analyser (RVA). University of Stellenbosch. 2011.
- ↑ a b Evans DE, Fox GP. 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.
- ↑ McCafferty CA, Jenkinson HR, Brosnan JM, Bryce JH. Limit dextrinase — Does its malt activity relate to its activity during brewing? J Inst Brew. 2004;110(4):284–296.
- ↑ a b 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.
- ↑ Bamforth CW, Fox GP. Critical aspects of starch in brewing. BrewingScience. 2020;73:126–139.
- ↑ Im H, Henson CA. 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.
- ↑ Andriotis VME, Saalbach G, Waugh R, Field RA, Smith AM. The Maltase Involved in Starch Metabolism in Barley Endosperm Is Encoded by a Single Gene. PLoS ONE. 2016;11(3):1–13
- ↑ Vriesekoop F, Rathband A, MacKinlay J, Bryce JH. The evolution of dextrins during the mashing and fermentation of all-malt whisky production. J Inst Brew. 2010;116(3):230–238.
- ↑ a b c Sacher B, Becker T, Narziss L. Some reflections on mashing – Part 2. Brauwelt International. 2016;6:392-397.
- ↑ a b c Ryder DS. Processing aids in brewing. In: Stewart GG, Russell I, Anstruther A, eds. Handbook of Brewing. 3rd ed. CRC Press; 2017.