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Barley can be separated into base grains, which provide the majority of fermentation sugars, and specialty grains which add color and flavor. In this article I’ll cover the base grains, and cover specialty grains in a future post. Base grains typically contain active enzymes, which are a necessary part of beer brewing. Enzymes are proteins that help facilitate chemical reactions, in this case the enzymes we are interested in will snip apart the larger starch molecules into more biologically useful sugars.
In order to break down the starch of the barley grains into fermentable sugars, malting facilities will soak the grains, allowing them to germinate and begin producing enzymes. The developing seedling would normally utilize these enzymes to mobilize the starch resources for growth. However, in this case the maltster will halt growth by heating and drying the grains. At this point the grains typically will be shipped to the brewer for beer production. Brewers crush the grains to open up the starch reserves to the enzymes.
The addition of heat will increase the rate of most chemical reactions, and the same is true for the breakdown of starch by barley enzymes. However, above a certain temperature, proteins will be inactivated as they begin to lose cohesion and fall apart, or denature. In the brewing process the crushed grain will be added to hot water, and kept at a temperature high enough to allow the reaction to happen quickly, but not so hot that the enzymes are denatured. Once the starch has been converted, the sweet liquid will be drained, and the grains rinsed with additional water. Typically, this will provide the source of all the sugars needed for fermentation.
Earlier in this series:
Yeast Inspection
An Introduction to Brewing Ingredients
Up Next: Specialty Grains