Enzymes
(In progress)
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 natural amylase enzymes. During the mash these enzymes convert 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.
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 take steps to inhibit them.
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.