Enzymes

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An enzyme is a protein that facilitates a chemical reaction. Enzymes play an important role in every fermented beverage.

For beer production, grain is malted in order to increase the amount of enzymes. Enzymes active during the mash include α- and β-amylase, proteases, peptidases, β- (1,3)(1,4)-glucanases and lipases. The most important action of these enzymes is that during the mash they break down the starches in the grain into fermentable sugars. Brewers may sometimes add extra enzymes such as glucoamylase in order to further break down the complex sugars (dextrins). Hops also have enzymes that can break down dextrins.

Proteolytic enzymes in the mash and their optimal temperatures:

• Endopeptidases (45-50°C)
• Carboxypeptidase (50°C)
• Aminopeptidase (45°C)
• Dipeptidases (45°C)

Lipoxygenases (LOX) oxidize fatty acids to hydroxy fatty acids, which are precursors to staling compounds. These enzymes are formed during malting and activated during milling and mashing. LOX activity is enhanced with a low dough-in temperature and pH closer to 6.0. Much of the LOX is destroyed during kilning, moreso in darker malts. Things that reduce LOX activity:

• Selecting a more kilned malt
• LOX does not require oxygen, however it is inhibited by preventing oxygen (air) from contacting the milled grain
• High dough-in temperature, high mash temperature, and short mash duration
• A more coarse crush
• Milling temperature?
• Low pH value

In wine production, a group of enzymes known as pectinase is commonly added to improve clarity and extraction.

Microbes use a large variety of enzymes in order to grow, survive, and conduct fermentation. (See Fermentation.)

Some enzymes can have a negative impact (such as polyphenol oxidase in fruit) and we can take steps to inhibit their undesirable effects.

The action of enzymes is influenced by pH, temperature, and other factors. High temperatures will permanently disable enzymes because the protein structure becomes irreversibly distorted, preventing them from functioning.

• https://www.researchgate.net/profile/David_Evan_Evans/publication/230559002_Assessing_the_impact_of_the_level_of_diastatic_power_enzymes_and_their_thermostability_on_the_hydrolysis_of_starch_during_wort_production_to_predict_malt_fermentability/links/5789973608ae5c86c99ae90f.pdf
• https://www.researchgate.net/profile/David_Evan_Evans/publication/226691242_The_Properties_and_Genetics_of_Barley_Malt_Starch_Degrading_Enzymes/links/578f1cf408ae81b4466ed501/The-Properties-and-Genetics-of-Barley-Malt-Starch-Degrading-Enzymes.pdf
• http://lowoxygenbrewing.com/forum/viewtopic.php?f=11&t=1821