ALCOHOL BY VOLUME

A measure of how much alcohol is contained in a standard volume of an alcoholic beverage.

ALCOHOL BY WEIGHT

A measure of how much alcohol is in an alcoholic beverage expressed as a percentage of the total beverage weight.

ALE

Refers to beer made with ale yeast (saccharomyces cerevisiae), which ferments better in warmer temperatures, creating a full-bodied, often fruity, flavor profile.

ATTENUATION

The reduction of specific gravity in wort caused through fermentation when yeast consumes wort sugars and converts them into alcohol and CO₂.

BRETTANOMYCES

A genus of single-celled yeast organisms that ferment sugar, and can produce desirable or undesirable characteristics.

CARBOY

A large bottle—glass, plastic, or earthenware—used for fermentation of wort.

DEGREES PLATO

A measure of the density of liquid, invented by Karl Balling in 1843, and refined later by Fritz Plato.

DIACETYL

A common off-flavor that has a butter or butterscotch-like flavor and aroma.

DIMETHYL SULPHIDE (DMS)

A common off-flavor that has the aroma and flavor of cooked vegetables or creamed corn.

FUSEL ALCOHOL

A family of high molecular weight alcohols caused by excessively high fermentation temperatures, imparting harsh characteristics, resembling paint thinner.

GRIST

Part of the beer recipe that is malt, particularly after it’s crushed; also known as the “grain bill.”

HOPS

The flowering and fruiting body of the plant Humulus lupulus; adds bitterness and flavor to beer.

IBU

International Bitterness Unit; One part-per-million of isomerized alpha acid, or 1 mg/liter.

KEG

A cylindrical vessel that holds carbonated beer under pressure. Homebrew kegs are generally 5 gallons in volume.

KRAUSEN

The head of foam which appears on the surface of wort during fermentation.

LACTOBACILLUS

Bacteria that converts unfermented sugars found in beer into lactic acid. Sometimes thought to spoil beer, but can be intentionally added to finished beer in order to add desirable sourness.

LAGER

German term meaning for “to store”; in brewing, refers to beer made with lager yeast (saccharomyces pastorianus), which ferments better in cooler temperatures, creating a more crisp, less fruity, flavor profile.

LAUTERING

The process of removing sugary liquid from the mash vessel.

LIQUOR

Refers to water used in the brewing process before grain has been infused into it.

MAILLARD REACTION

The result of applying heat to brown food and drink, creating flavor and changing the color.

MALT

Barley forced through a false germination process, then kilned, creating a reserve of starch and enzymes that will transform into sugar during the mashing process.

MALT EXTRACT

Powdered or liquid malt made to take the place of mashing/grain in a homebrew setting.

MASH

The mixture of grain and hot water that forms the wort.

MASH TUN

The vessel in which the grain is soaked in water and heated, converting starch to sugar and extracting sugars, colors, flavors for brewing.

PEDIOCOCCUS

Bacteria usually considered contaminants of beer, although their presence is desirable when for some beer styles.

SACCHAROMYCES

The genus of single-celled yeasts that ferment sugar, and are commonly used in brewing.

SPARGING

The action of rinsing hot water over the top of the mash filter bed during lauter, which assists in removing sugar from the grain.

SPECIFIC GRAVITY

A measure of the density of liquid expressed in a ratio of the density of a substance to the density of a reference (eg., wort-to-water).

TRANS-2-NONENOL (T2N)

A common off-flavor that has the flavor of wet newspaper or cardboard.

TRUB

Residual proteins, hop oils, and tannins produced during the boiling and cooling stages of brewing.

VORLAUF

The process of recirculating liquid from the bottom of the mash vessel to the top of the mash vessel, in order to set the grain into a filter bed.

WORT

Unfermented beer; specifically, the liquid that will become beer, before yeast has been added to it.

YEAST

A unicellular fungus that metabolizes sugar and secretes ethanol, CO₂, and hundreds of flavor compounds that make beer both alcoholic and delicious.