Enzymes

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Enzymes and their role in gluten-free brewing

Enzymes play an important function as biological catalysts in both conventional and gluten-free brewing and perform a wide array of tasks during the brewing and fermenting process. A key area of enzyme interest for gluten-free brewers is in amylolytic enzymes that convert starch to sugar.

Amylolytic enzymes

Amylose is a linear polymer of glucose mainly linked with α(1→4) bonds
Amylopectin molecule

In partial and all-grain mashing, amylolytic enzymes help to convert starches in the "grain bill" to fermentable and non-fermentable sugars. Those starch sources are typically malted grains, but can also include unmalted grains and root vegetables. The enzymes responsible for this starch to sugar conversion occur naturally in grains and root vegetables as part of the plant's growth cycle (whereby enzymes unlock stored energy needed for growth). The malting process aids in developing these enzymes for use by brewers during mashing. Diastatic power is an indicator of how capable enzymes are of breaking down starches into simpler sugars during the mash.

Amylolytic enzymes include a variety of different types that play different roles in breaking down the two major types of starch:

  • Amylose
    • A long string of glucose molecules connected by more simple (1-4) bonds (the numbers identifying which carbon atoms join the two molecules).
  • Amylopectin
    • These are more complex starch chains composed of amylose branches that are joined via (1-6) bonds.

Categories of amyloytic enzymes

Alpha amylase

Encompass a variety of enzymes that are capable of hydrolyzing (breaking down) amylose at random points along the starch chain (breaking the 1-4 glycosidic bonds). This generates shorter chains of varying length: single glucose molecules, maltose (two glucose molecules), maltotriose (three glucose molecules) and longer chains of polysaccharides / dextrins. "Maltogenic" alpha amylase enzymes are ones that favor production of maltose.

Beta amylase

Maltose producing enzyme that work from the ends of amylose chains rather than randomly breaking them (as per alpha amylase). Works on larger starch molecules before moving to smaller residual molecules.[1]

Glucosidase

Glucose producing enzymes that work at the non-branching ends of amylose and amylopectin starch chains.

Limit dextrinase

Also known as pullulanase, this class of enzyme is able to break the (1-6) glycosidic bonds that represent the branch point of amylopectin molecules. Limit dextrinase aids in creating a more fermentable wort by making available new amylose chains that can be acted on by other maltose and glucose producing enzymes.

Endogenous enzymes

Endogenous enzymes are those that are naturally incurring in the grain. In general gluten free grains have a lower concentration of the amylolytic enzymes responsible for liquefaction and sugar production than malting barley. This is evident in their lower diastatic power (DP) ratings. While these enzymes are present in small amounts, it may be necessary to supplement them with exogenous ones, and to take measures to avoid denaturing them at the higher gelatinization temperatures required for GF grains.

Between millet, sorghum, rice and buckwheat, millet appears to have the highest endogenous (naturally occurring) diastatic power. Enzymes can be denatured (i.e. made ineffective) through high kilning temperatures and/or high gelatinization temperatures. Dark roasted grains and crystal malts thus usually have no diastatic power.

Sweet Potato

Several elongated reddish brown tubers
Several elongated reddish brown tubers

Sweet potato (Ipomoea batatasis) is a natural source of alpha-amylase and beta-amylase, the latter a rare commodity outside of endogenous enzymes from malted grains. The names sweet potato and yam (genus Dioscorea) are often used interchangeably in North America [2], though the two are different species. Sweet potatoes are relatively low in protein but a source of starch as well as amylase for starch conversion. Optimum activity for alpha amylase activity was found to be at 71.5 C (160-161 F) -- however heat denatured in the absence of calcium (Ca2+) above 63C (145F). Alpha-amylase optimum pH is between 5.8 and 6.4. Sweet potato beta-amylase is heat stable up to 60C (140F) but optimum at 53C (127F) and a pH between 5.3 and 5.8.[3] The diastatic power of sweet potatoes was determined by one study to be 207 °WK (63.7°Lintner) compared to 231 °WK for rice malt and 418 °WK for the barley malt sample.[4] The same study found that sweet potato (thinly sliced, dried at 40C, and then milled) was an effective enzyme source for sorghum malt based beer given malted sorghum's low diastatic power (54 °WK). For gluten-free brewing, it may be worth employing sweet potatoes for enzymatic help either during an initial pre-saccharification rest at 53-60C (127-140F) or towards the end of a reverse mash step after 1,6- glucose bonds and larger amylose chains have been broken down.

Exogenous enzymes

Many gluten-free brewers working with gluten-free grains rely on commercially available exogenous enzymes to do the heavy lifting of converting starch to sugar. These enzymes are primarily synthesized from bacterial or fungal sources and are available in liquid format. Gluten-free brewers may use a combination of these enzymes with different dosing rates at specific temperatures and pH levels during the mash.

List of Commercial Enzymes for Gluten Free Brewing

Enzyme Manufacturer Type Min Dosage (ml/lb) Max Dosage (ml/lb) Effective Min Effective Max pH Range Notes
SEBAmyl Bal 100 Enzyme Innovation Alpha Amylase 0.136 0.408 155°F 165°F 5-6.5 Bacterial alpha-amylase enzyme. See notes for temp range variance.[5]
SEBAmyl L Enzyme Innovation Alpha Amylase 0.113 0.227 140°F 170°F Medium temperature, maltogenic fungal alpha amylase.
SEBAmyl GL Enzyme Innovation Glucoamylase 0.227 0.454
SEBstar HTL Enzyme Innovation Alpha Amylase 0.091 0.363 180°F 190°F
Termamyl L Novozymes Alpha Amylase 0.227 0.363 30C (86F) 95C (203F) Popular choice for mashing at high temperatures where endogenous amylolytic enzymes would otherwise denature. It is produced from a strain of Bacillus licheniformis. Calcium (Ca++) helps to stabilize at higher temps and lower pH values.[6]
Termamyl SC DS Novozymes 0.091 0.272
AG 300L Novozymes Glucoamylase, alpha amylase 0.227 1.588
Fungamyl 800L Novozymes Alpha Amylase 0.036 0.227 50C (122F) 60C (140F) Maltogenic fungal alpha amylase. Similar in function to SEBAmyl L
Attenuzyme Pro Novozymes Glucoamylase, pullulanase 0.091 0.907
Ondea Pro Novozymes 1) Beta glucanase, 2) xylanase, 3) alpha amylase, 4) pullulanase, 5) protease, 6) lipase 0.181 1.134 53C (127F) 64C (147F)
Ceremix Flex Novozymes 1) pullulanase, 2) alpha amylase Maltogenic fungal alpha amylase

Termamyl

Termamyl is a heat-stable alpha amylase enzyme. It is manufactured by Novozymes and stable to 105-110 C (221-230 F). This makes it a popular choice for mashing at high temperatures where endogenous amylolytic enzymes would otherwise denature. It is produced from a strain of Bacillus licheniformis.

Sebamyl BAL

Sebamyl L

Same enzyme as Fungamyl, but different manufacturer. Also derived from aspergillus oryzae. Per Aaron Gervais (Otherwise Brewing), may have different dosage rates.

Fungamyl 800L (aka Fungamyl BrewQ)

"Fungamyl 800 L is a fungal alpha-amylase obtained from a selected strain of Aspergillus oryzae". Prolonged exposure is reported to result in formation of a high concentration of maltose, thus it may be an acceptable substitute for beta amylase when seeking maltose (vs. glucose) production. The product is manufactured by Novozymes. Less heat tolerant than Termamyl, Fungamyl 800L is primarily active between 50 - 60 c (with very limited activity at 65 c and higher). Relative activity is greatest between 5 and 6 pH. [6]

AMG

Ondea Pro

Combines multiple enzymes including pullulanase, α-amylase, cellulase, xylanase, protease, and lipase. The key feature for gluten free brewers is pullulanase a debranching enzyme that hydrolyzes (1,6)-alpha-D-glucosidic linkages in pullulan, amylopectin and glycogen. Because the different enzymes are effective and denature at different temperatures, it will be more effective in a rising temperature mash routine — and enzymes should be added prior to saccharification steps. Product literature suggests starting at 53c and rising to 64c (max).

Ceremix Flex

Other enzyme functions

  • Reduce viscosity
    • Xylanases, Cellulases, Hemi-cellulases, Beta-glucanases
  • Improve yeast nutrition, reduce protein haze and increase shelf stability
    • Proteases (FAN production)

See also

  • Prolyl endopeptidase. Primary purpose to clarify beer by precipitating protein-haze. See Gluten Reduced vs Gluten Free beer.
  • "Hop creep" is the phenomenon wherein heavily dry-hopped beers undergo unintended additional fermentation after the beer is thought to have stabilized (i.e. reached terminal gravity). This can occur when enzymes associated with the hops (primarily alpha and beta amylase, but also glucosidase and limit-dextrinase) convert some of the remaining dextrins to fermentable sugars. In beers where yeast is still present and at temperatures warm enough to permit yeast activity, this can lead to further fermentation, diacetyl production, and potential packaging problems.[7]

External Links

  • K. Muoria, John & Linden, James & Bechtel, Peter. (1998). Diastatic Power and alpha-amylase Activity in Millet, Sorghum and Barley Grains and Malts. Journal of the American Society of Brewing Chemists. 56. 131-135.
  • Enzymes in Brewing MBAA
  • Otherwise Brewing Blog, Enzymes for Gluten Free Brewing
  • Aaron Gervais's GF enzymes dosage calculator


References

  1. Alan Windhausen, Practical Enzymatic Brewing, Craft Brewers Conference presentation, May 4, 2020.
  2. https://www.thekitchn.com/whats-the-difference-between-yams-and-sweet-potatoes-word-of-mouth-211176
  3. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2621.1994.tb06970.x Sweetpotato α‐ and β‐Amylases: Characterization and Kinetic Studies with Endogenous Inhibitors
  4. Improving the Saccharification of Sorghum Mash With Supplementary Enzymes From Local Crops
  5. Manufacturer's website provides a wider range for liquefaction: 140-170°F. Enzyme Innovation, Liquefaction Enzymes
  6. http://www.ebiosis.co.kr/Novozymes%20Product%20Sheet/Fungamyl%20800L.pdf
  7. MBAA podcast, episode ...