ABV: alcohol by volume, the common method of measuring alcohol content in beer.
Acetobacter: an aerobic bacteria that produces acetic acid in a beer, generally undesirable except in a few styles, such as lambic and Flemish red or brown ales.
Ale: family of beer that ferments at warmer temperatures, also called “warm-fermenting” or “top-fermenting” because of the action of ale yeast
Attenuation: the degree to which fermentable sugars are converted into alcohol as influenced by yeast, mash conditions and ingredients among other things.
Bottom-Fermenting: a term for the lager family of beers, based on the tendency of lager yeast to be active at the bottom of a fermentation tank
Barley, two-row and six-row: refers to the number of kernel rows in the head of the stalk, two-row is the more commonly used, whereas six-row is employed when extra amylase enzymes are required to convert other grains.
Brettanomyces: a yeast that produces horsey, cheesy or barnyard aromas and flavors, generally undesirable in beer except in lambics and a few others.
Cask: the traditional container for all beer, in modern times it has come to mean a barrel-type container that is used for real or cask-conditioned ale, dispensed via gravity or hand pump at cellar temperatures.
Decoction: a traditional German procedure where a portion of the mash is heated to boiling separately and returned to the main mash to raise the whole stepwise through ideal enzymatic ranges.
Drum Kiln: a cylindrical kiln used to produce malts of myriad colors and properties without the application of direct heat.
Fermentation: the process by which yeast metabolizes simple sugars into alcohol
Gravity: short for specific gravity, or the measure of density of a liquid.
Grist: crushed or milled grain before it is mixed with hot water to form a mash.
Hops: the cone-shaped flowers of the vine Humulus lupulus, used to give beer its bitterness and aroma, and as a preserving agent.
Hydrometer: an instrument that measures the specific gravity of a liquid; in the case of brewing, it enables brewers to measure the concentration of sugars in wort or the progress of fermentation as the sugars are converted to alcohol.
IBU: International Bittering Units, a measure concentrations of various hop compounds in a beer, an indication of the beer’s bitterness.
Lactobacillus: an anaerobic bacteria that produces sour notes in a beer, generally undesirable except in a few styles, such as lambic and Flemish red or brown ales.
Lager: family of beer that ferments at cooler temperatures, also called “cold-fermenting” or “bottom-fermenting” because of the action of ale yeast.
Malt: grain (usually) barley, that is allowed to germinate, with the process stopped by heat. The amount and duration of the heat determines the color and other qualities of the malt, which govern the color of the beer and many flavor components.
Mash: a mixture of milled grain ( grist ) and water used to produce fermentable liquid.
Mashing: the process by which a mash undergoes temperature-dependent enzymatic changes to create wort for fermentation by breaking down proteins and converting starch into both fermentable sugars and unfermentable dextrine.
Melanoidins: heat-catalyzed chemical reactions that enhance color, aroma and flavor of malt or wort via the interaction of sugar and protein components.
Modified/Under-Modified: the degree to which barley starches are converted by a malt-producer; under-modified malt requires more manipulation by the brewer during mashing than highly-modified.
Noble Hops: hop varieties, including Hallertauer Mittelfruh, Tettnang Tettnanger, Spalt Spalter and Czech Saaz, prized for their aromatic qualities
Parti-Gyle: an ancient brewing practice where successive beers are produced by draining the mash and re-saturating several times to create incrementally weaker beers from a single mash.
Reinheitsgebot or the Bavarian Purity Law of 1516: A law that mandated that beer could be made only from malted barley, hops and water; amended later to include yeast.
Sparge: the process where hot water is sprinkled on the top of the mash at the same rate as it is drained into the boiling kettle to leach all of the components out of the grist.
Top-Fermenting: a term for the ale family of beers, based on the tendency of ale yeast to be active at the top of a fermentation tank
Yeast: in the making of beer, the micro-organism that ferments sugar into alcohol