Homebrewer's Glossary

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Homebrewer's Glossary

You’ll hear a lot of brewing terms tossed around and maybe you are not entirely sure what they mean. Homebrewing is a science and it has a language all of its own. From Ale to Zymurgy, here's the Philly Homebrew Outlet's official Homebrewer's Glossary:


Ale - A beer brewed from a top-fermenting yeast with a relatively short, warm fermentation.


Alpha Acid Units (AAU) - A homebrewing measurement of hops. Equal to the weight in ounces multiplied by the percent of alpha acids.


Attenuation - The degree of conversion of sugar to alcohol and CO2.


Beer - Any beverage made by fermenting a wort made from malted barley and seasoned with hops.


Cold Break - Proteins that coagulate and fall out of solution when the wort is rapidly cooled prior to pitching the yeast.


Conditioning - An aspect of secondary fermentation in which the yeast refine the flavors of the final beer. Conditioning continues in the bottle.


Fermentation - The total conversion of malt sugars to beer, defined here as three parts, adaptation, primary, and secondary.


Hops - Hop vines are grown in cool climates and brewers make use of the cone-like flowers. The dried cones are available in pellets, plugs, or whole.


Hot Break - Proteins that coagulate and fall out of solution during the wort boil.


Gravity - Like density, gravity describes the concentration of malt sugar in the wort. The specific gravity of water is 1.000 at 59F. Typical beer worts range from 1.035 - 1.055 before fermentation (Original Gravity).


International Bittering Units (IBU) - A more precise unit for measuring hops. Equal to the AAU multiplied by factors for percent utilization, wort volume and wort gravity.


Krausen (kroy-zen) - Used to refer to the foamy head that builds on top of the beer during fermentation. Also an advanced method of priming.


Lager - A beer brewed from a bottom-fermenting yeast and given a long cool fermentation.


Lag Phase - The period of adaptation and rapid aerobic growth of yeast upon pitching to the wort. The lag time typically lasts from 2-12 hours.


Pitching - Term for adding the yeast to the fermenter.


Primary Fermentation - The initial fermentation activity marked by the evolution of carbon dioxide and Krausen. Most of the total attenuation occurs during this phase.


Priming - The method of adding a small amount of fermentable sugar prior to bottling to give the beer carbonation.


Racking - The careful siphoning of the beer away from the trub.


Sanitize - To reduce microbial contaminants to insignificant levels.


Secondary Fermentation - A period of settling and conditioning of the beer after primary fermentation and before bottling.


Sterilize - To eliminate all forms of life, especially microorganisms, either by chemical or physical means.


Trub- The sediment at the bottom of the fermenter consisting of hot and cold break material, hop bits, and dead yeast.


Wort - The malt-sugar solution that is boiled prior to fermentation.


Zymurgy - The science of brewing and fermentation.