This is a subset of the terms listed at BYO Magazine‘s comprehensive Brew Glossary.

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O

P | Q | R | S | T | U | V | W | X | Y | Z

A

adjunct: any substitute unmalted grain or fermentable ingredient added to a mash. Reduces cost and produces lighter-bodied, paler, and less malty beers.

aeration: exposing a substance to air, performed at various stages of the brewing process.

airlock (or fermentation lock): a one-way valve that allows carbon dioxide gas to escape while preventing the entry of contaminants.

ale: a generic term for beers produced by top fermentation (i.e. using ale yeast strains) at temperatures higher than lager fermentation temperatures; wort usually made by infusion mashing.

alpha acid: the soft, bitter hop resin responsible for most of beer¹s bitterness. Alpha acids must be boiled to convert alpha acids to iso-alpha acids. Measured as a percentage of the total weight of the hop cone.

all-grain beer: a beer made entirely from malted grains, as opposed to beers made from malt extract.

amylase: generic name for enzymes that break the bonds holding starch molecules together.

attenuation: the drop in specific gravity that occurs as a wort goes through fermentation.

B

bacteria: one-celled organisms that reproduce rapidly under strict temperature, pH, and other conditions. (Bacteria can be killed with disinfectants.)

bitterness units (BU): a system to express the bitterness in beer with a unit based on alpha acid content. The homebrewers’ bittering unit estimates the bitterness of hopped malt extract by multiplying the amount of hops by the alpha acid unit of the hops used.

bottle-conditioned: beer carbonated naturally in the bottle by priming or re-yeasting.

break: the clumping and separation of protein matter during the boiling stage (hot break) and cooling stage (cold break).

brilliance (or brightness): description of beer in terms of clarity and effervescence (also called purity).

C

caramel malt: a malt that is prepared by “stewing” (kilning in a moist environment) to produce sugars from starch (the sugars caramelize when the malt is dried to yield color and flavor compounds). Also called crystal malt.

carbonation: injecting or dissolving carbon dioxide gas in a liquid to create a bubbly taste and texture.

carboy: a large glass or plastic vessel with a narrow neck.

conditioning: the process of carbonating beer.

crystal malt: another name for caramel malt (see earlier).

D

decoction mashing: the method of removing some of the mash, boiling it, then returning it to the main kettle to boost the mash temperature (this process is used in all-grain brewing).

doughing in (or mashing in): mixing ground malt with water, the first step in all-grain brewing.

dry hopping: the practice of adding hops to the primary or secondary fermenter (or to finished beer) to increase the aroma and hop flavor of the beer without increasing its bitterness.

E

enzyme: a protein that acts as a biological catalyst for chemical reactions, such as alpha-amylase, which converts starch to maltotriose and dextrin sugars, or beta-amylase, which converts dextrins to simpler sugars: maltose, glucose and smaller dextrins.

extract brewing: making beer from malt extract syrup or powder as opposed to unprocessed malt (which is used in all-grain brewing).

F

fermentation: the process by which yeast releases energy in the absence of oxygen by breaking sugar into carbon dioxide and alcohol.

G

grist: crushed malt and adjuncts mixed with hot water for mashing.

gypsum: hydrated calcium sulfate used to treat soft or neutral water making it hard.

H

heat exchanger: equipment used to heat or cool the wort rapidly.

high gravity: an original wort gravity of 1.060 or greater.

hops: the flowers or cones of the female hop plant used in brewing to impart flavor and bitterness. These can be used whole, or in form of pellets or plugs.

hot break: the precipitation of protein and tannic matter when hops are added to boiling wort.

hydrometer: a glass instrument used to measure the specific gravity of beer by comparing it to that of water.

I

IBU (International Bitterness Unit): unit of measurement used to express a beer¹s bitterness as milligrams of iso-alpha-acid (a compound created when alpha acids are boiled) per liter of beer.

Infusion mashing: the traditional British method of mashing, primarily used in ale brewing. It occurs at a single temperature and is carried out in a combination mash-lauter vessel called an infusion mash tun.

Irish moss: a red seaweed added at the end of the boiling process as a fining agent.

J

K

kettle: a large vessel used to heat wort.

kraeusen: the fluffy head of foam that forms on the surface of wort during the first few days of fermentation. At its peak it is called “high kraeusen.”

L

lactic acid: an acid produced by bacteria during mashing or (more frequently) during fermentation and aging via contamination.

lager: (n.) any beer produced by bottom fermentation. (v.) Aging beer at cold-storage temperatures.

lauter: to separate the wort produced during mashing from the spent grains (husks and coagulated protein).

lauter tun: a large, perforated, false-bottomed vessel used to strain the sweet wort from the spent grains after mashing. Sometimes the mash tun is used for both mashing and lautering.

Lovibond: the scale often used to evaluate malt, wort and beer color.

M

malt: barley or other grain steeped in water and germinated to create enzymes to be used in mashing, then kilned to stop the growth of the grain and to reduce moisture.

malt extract: wort concentrated into a syrup or powder by removing all or most of the water.

mash: (n.) a mixture of milled malted grains and hot water used to produce the sweet wort needed in brewing. (v.) mixing ground malt with hot water in the mash tun to extract the malt starch and convert it to grain starches and fermentable sugars.

mash tun: a vessel used to hold the mash in infusion brewing. May be fitted with a perforated false bottom to remove the sweet wort produced during mashing from spent grains.

milling: grinding the malt into grist before extracting sugars during mashing.

modification: the net physical changes that occur within the barley kernel as it is converted from barley to malt.

N

natural conditioning: a secondary fermentation that occurs during ageing. During this maturation period there are still live yeast in the beer.

nutrients: like any living creature, yeast require nutrients to remain healthy while performing their duty (i.e. fermentation). The essential nutrients are nitrogen and phosphorous, which are typically packaged and sold as “yeast nutrients” to add right after pitching your yeast.

O

original gravity (OG): this is the specific gravity of a wort before it goes through any fermentation. The measurement tells you the amount of solids that are in a wort in reference to that of pure water at a certain temperature (which is given the value of 1.000 SG).

P

pasteurization: A stabilizing technique that uses high heat in packaged materials or brew to kill microorganisms. This process also prevents post packaging fermentation in brews and lengthens shelf life.

pH: the commonly used abbreviation for “potential hydrogen.” This measurement is given a number between 1-14, representing the acidity or alkalinity in a solution. A solution below 7 pH is considered acidic and a solution above 7 is alkaline.

potential alcohol: the estimated amount of alcohol that a final brew will have. This measurement is based on the pre-fermentation sugar content.

primary fermentation: the first phase of fermentation where sugars are converted into ethyl alcohol and carbon dioxide.

priming: the practice of adding sugar to fermented brew before bottling to reintroduce fermentation and carbonate the brew in bottle.

R

rack: to move beer from one container to another, typically from a primary to secondary fermenter in order to separate beer from the solids that fall out of solution during the initial fermentation period.

racking cane: a plastic tube with an arced end that is attached to a hose and used to siphon brew. The arced end stays above the solids when lowered to the bottom of a fermenter and helps to leave sediment behind.

real ale: an ale that hails from England and is cask-conditioned in the cellar. Real ales are often served from casks in the pub with a beer engine.

rest: during the mash, brewers hold the mash at a predetermined temperature in order to draw out certain enzymes from the grain.

RIMS: an acronym for Recirculating Infusion Mash System, a type of brewing system that many homebrewers use.

runoff: a synonym for wort, or the liquid that you separate from the spent grain husks during lautering.

S

saccharification: the process of converting starches contained in malt into fermentable sugars.

secondary fermentation: the second, slower stage of fermentation that takes place after primary fermentation has forced solids out of solution and the brew is racked to a closed bin (the “secondary fermenter”).

sediment: the solid material that falls out of solution during fermentation (more so in the primary fermentation, but also in the secondary for certain brews.)

soft water: water that is free of calcium, magnesium, cholorine, iron and other elements that otherwise contribute to “hard water.”

sparge: a process that brewers conduct during mashing in which spent grains are sprayed with hot water in order to extract the remaining sugars from the husks.

specific gravity (SG): a measurement that represents the density of a liquid at a specified temperature. Pure water is given a value of 1.000 SG at 39 ºC (4 ºC). This measurement is highly used in brewing in order to monitor various processes from boiling throughout fermentation.

T

terminal gravity: a term used to define the specific gravity after a beer has fermented and aged appropriately. A synonym that is commonly used is final gravity.

top fermentation: a fermentation method that utilizes yeast that hover on the surface as opposed to sinking to the bottom. Ales are “top fermented” beers while lagers are bottom fermented.

U

V

vorlauf: German word referring to the process of recirculating wort through the grain bed.

W

wort: the sweet solution created by boiling malt, hops and water. It is high in sugar and ferments when yeast is added.

Y

yeast: A single-celled organism of the genus Saccharomyces. During fermentation, yeast convert sugar into alcohol and carbon dioxide.

yeast nutrients: These are elements that can be added to a fermentation to promote yeast health and vitality. Homebrew supply shops sell pre-measured packages of yeast nutrients for small batches.

Z

zymology (or zymurgy): the science of fermentation