Home Brewing

Glossary of Brew Terms

Welcome to the wonderful world of brewing! We have compiled this glossary to help you get a better understanding of common brewing terms


This volatile compound has the taste and aroma of fresh-cut green apples. It is normally reduced to ethanol by yeast during the secondary fermentation, but oxidation of the finished beer may reverse this process, converting ethanol to acetaldehyde.

Elevated levels of acetaldehyde are generally present in green beer or if the beer is prematurely removed from the yeast. Using refined cane sugar as an adjunct in your brew will generate excessive quantities of acetaldehyde. It can also be a produced as a result of bacterial infection by Zymomonas or Acetobacter bacteria.


Unmalted grain, sugars or syrups used in brewing. These are added for a number of reasons: reduce cost, increase alcohol volume or to change colour or to improve flavour and body of the beer. Honey, Candy Sugar and Dextrose are examples of commonly used adjuncts.


To mix air into solution to provide oxygen for the yeast. Generally done through stirring wort before or after pitching. 


A device used on a fermenter that allows carbon dioxide to escape while stopping the entry of any undesirable bugs, gases and the like from entering. Several styles are available, most common are ‘S-type’ airlock and the ‘3 piece’ airlock. These are filled with water (or sterilised water) to prevent  contamination.


Alcohol By Volume. A measure of the percentage of alcohol volume over the total volume of the brew.


A chemical precursor to alcohol. In some cases, alcohol can be oxidized to aldehydes, creating off-flavours.


A beer that’s brewed  with a top-fermenting yeast that is fermented at warmer temperatures (19°C to 25°C). Ale fermentations are generally shorter than lager fermentations.


The condition of pH between 7-14. The chief cause of alkalinity in brewing water is the bicarbonate ion (HCO3-1).

All Grain Brew

Refers to a beer that’s been brewed using only a combination of malted and unmalted grains.

Alpha Acid

One of the resins found in hops, produced by the lupulin glands on the hops flower. This converts to bittering compounds during the boiling process.

Alpha Acid Units (AAU)

A homebrewing measurement of hops and hop bitterness. Equal to the weight of 28g multiplied by the percentage of Alpha Acids. 

AAU’s do not take into consideration such important factors as batch size, boil time or specific gravity, for this reason the use of AAU’s has been largely replaced by International Bitterness Units (IBU).


An enzyme group that converts starches to sugars in the brewing process. This consists primarily of alpha and beta amylase. Also referred to as the diastatic enzymes.

Aroma Hops

Hops added to a brew specifically for the addition of aroma. They may be added during the last few minutes of a mash or boil or dry hopped during fermentation. 

Aroma hops generally do not contribute to the bitterness of a beer. These are also commonly referred to as Noble Hops.


Refers to a mouth-puckering, harshness or dryness in the finish of the flavour of a beer. Astringency can be caused by over-sparging grain in an all grain brew or steeping grain too long or at too high a temperature. It can also occur as a result of over-oxidising a brew or through a bacterial infection.


Is the percentage of sugars that a strain of yeast will consume. The fermentation conditions and specific gravity of a particular beer will cause the attenuation to vary, hence each strain of brewers yeast has a characteristic attenuation range, typically between 65-85%.


When yeast run out of nutrients and die, they release their innards into the beer, producing off-flavors and a rubbery stench

Base Grain

The malted grain that serves as the main part of the beer and the main source of fermentable sugars and flavour of the beer.


A hard organo-metallic scale that deposits on fermentation equipment composed of calcium oxalate. Can be avoided with proper cleaning and sanitising.

Beta Acid

Three different acids (Lupulone, Colupulone and Adlupulone) that are found in the resin produced by the lupulin glands on the hops flower. Unlike the alpha acid group, these acids do not contribute greatly to the bitterness of the brew. They contribute more to the aroma of the brew and act as a natural preservative.

Beta Glucanase

An enzyme that assists in the breaking apart of starch molecules in unmalted barley, oatmeal and wheat during the mashing process.


A type of airlock arrangement consisting of a tube exiting from the fermenter, submerged into a bucket of water. This allows the release of carbon dioxide and removal of excess fermentation material.


The fullness or thickness of a brew on the palate, commonly known as mouth feel. Body can be enhanced by adding unfermentable (complex) sugars such as dextrose or maltodextrins or increasing proteins in your brew. Improving the body of a brew will also improve head retention.

Bottle Conditioned

Beer that has undergone secondary fermentation in the bottle. The addition of extra fermentable sugar (carbonation drops, table sugar etc) during the bottling stage provides the yeast with just enough food to naturally carbonate the beer.

Bottle Filler 

Rigid plastic tube often with a spring loaded valve at the tip, used to connect to a fermenter tap for filling bottles.


When proteins coagulate and fall out of the solution. The hot break occurs during the actual boil while the cold break occurs during the wort chilling process.


A chemical species, such as a salt, that by disassociation or re-association stabilizes the pH of a solution.

Carbon Dioxide

One of the major by-products produced by yeast as it metabolises sugars during fermentation. The process of dissolving Carbon Dioxide in beer is referred to as Carbonation. Generally each beer style has a carbonation level associated with it. Some beers require low levels of carbonation (stouts, porters) while others may require more (German and Belgian beers).


A  container used by some brewers as a fermentation vessel. Generally glass or plastic and either have rubber bungs or screw lids. Capacities are generally 5 litres to 60 litres in volume.

Cellar Temperature

Adopted from the UK and refers to the generally accepted optimal temperature that ales should be served: 7°C – 12°C.

Chill Haze

A precipitation of proteins and tannins in beer that appears when the beer is chilled. As the temperature increases, this will usually disappear. Can be reduced through the use of finings or Irish Moss in the later stages of a boil or ferment.


Overly sweet in flavour to the point of being unpalatable. Often the result of excess malt or a lack of hops.  


The process of maturing beer over a period of time. Done at the same temperature as the primary fermentation, bottled beer will become carbonated during this period. 


The process during the mash of grains in beer where enzyme activity converts starch to sugar. This generally occurs between 60°C and 70°C.


Pertaining to the finish of a beer. A crisp finish will be dry and fizzy. This kind of finish can be achieved with the addition of a dry enzyme during the fermentation that assists in the breakdown of normally unfermentable sugars.


A complex method of mash brewing that involves raising the temperature of the mash in steps by removing a portion of the mash, boiling it, and returning it to the mash tun


A complex, unfermentable sugar molecule derived from starches during the mash process that contributes to the body and mouth feel of a beer.


Equivalent to Glucose, a simple sugar predominantly extracted from corn. Also known as corn sugar.


A term used to describe a beer that exhibits a buttery or butterscotch flavour to its finish. It is a volatile compound that is produced by some strains of yeast when a beer has been fermented at warmer than optimal conditions. 

Diastatic Power 

The amount of diastatic enzyme potential that a malt contains.

Dimethyl Sulfide (DMS)

A powerful aromatic compound that imparts a cooked-corn smell to beer. It is usually a by-product of lager style grains and can generally be acceptable in very low amounts in lagers.

DME – Dry Malt Extract

A powdered concentrate form of unhopped malt.


The spent grain and other solid matter left in the mash tun or kettle after starch conversion is complete.

Dry Hopping

Addition of fresh or dry hops directly to fermenting beer in order to accentuate the hop aroma and flavour in the finished product. Popular in styles like West Coast IPAs, New England IPAs and Milkshake IPAs.


The nutritive tissue of a seed, consisting of carbohydrates, proteins, and lipids.  It is this substance that is converted via enzyme activity to fermentable sugar during the mashing process.


The kind of unpleasant aroma that emanates from a beer that has a foul, almost rotten odour. If your beer produces an enteric aroma, there’s a good chance that it has been the target of a wild yeast contamination or a bacterial infection.


Protein based enzyme activity during the mash stage of brewing that converts starch molecules to sugars.


Aromatic compounds formed from alcohols by yeast action. It is a volatile substance that contributes a fruity aroma to beer.


A volatile, flammable, colourless liquid produced by yeast as a result of its metabolising of sugars during fermentation.

EBC – European Brewing Convention 

The colour graduation method developed in Europe for measuring the colour of malts and beers.


The result of the removal of water from a unhopped wort. Can be a thick liquid concentrate or a dried powder.

Extract Brewing

Extract brewing involves the use of concentrated malt extract in the brewing process. The main advantage of this style of brewing over all grain brewing is that it allows novice and intermediate brewers to skip the mash and lauter steps, and move straight into boiling the extract with hops. This cuts the total brew time down and reduces the amount of equipment required.


The process of conversion of fermentable sugars in wort, by yeast, into alcohol and carbon dioxide. Fermentation can be defined as three parts; adaptation, primary and secondary.

Final Gravity

The specific gravity of a beer measured at the end of the fermentation period.


The point at the end of the boil where the flame is extinguished. Some beer recipes will call for the addition of hops at this point in order to add aroma and flavour, but no bittering.


It is the clumping and settling of the yeast in beer wort.


Substances such as isinglass, bentonite, gelatine and Irish moss used to clarify beer by precipitating particulate matter out of suspension. 


Also known as aftertaste, it is the final impression of the beer according to your taste buds after sampling the product.

Finishing Hops

Hops added to a beer for aroma and flavour. Often added at the tail end of a boil, flameout or dry hopped during fermentation. 

Fusel Oils

A group of higher molecular weight alcohols that esterify under normal conditions. These products are often created by yeast at higher fermentation temperatures. When present after fermentation, fusels have sharp solvent-like flavours and are thought to be partly responsible for hangovers.


The process of rendering starches soluble in water by heat, or by a combination of heat and enzyme action.


The most basic unit of sugar. 


Gravity in brewing, describes the concentration of malt sugar in the wort. The specific gravity of water is 1.000 at 15c. The alcohol content of beer is measured by taking the gravity reading at the end of fermentation (FG) away from the gravity reading (OG) at the start of the fermentation process.


Cracked grain that is ready to be used in brewing. This is mixed with hot water in preparation for mashing.


An old fashioned mixture of herbs used for bittering and flavouring beer prior to the use of hops.


Calcium Sulphate  used to balance the pH level of water prior to brewing.


The white foamy layer of bubbles covering the surface of a freshly poured beer. The bubbles contain carbon dioxide while the bubble walls consist of proteinaceous matter from within the beer.

Head Retention

The long term stability of the head on a beer.


The flowers of a plant called Humulus Lupulus. Hops provide bitterness to balance the sweetness of malt, flavour and aroma and also help stabilize and preserve beer. 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.. The flowers are usually green in colour with yellow lupulin glands between the petals that provide many of the essential oils. The hop plant is the closest living relative to the cannabis plant.


A vessel that is filled with hops to act as a filter for removing the break material from the finished wort.


The outer covering of most cereal grains. The husk needs to be cracked (via a grain mill) prior to steeping or mashing the grain to allow access to the starchy endosperm.


A floating instrument used for determining the specific gravity of liquid. It is usually a hollow glass or metal instrument, weighted at one end so as to float upright. The stem of the instrument is graduated so as to indicate the gravity of the liquid. Hydrometers are necessary when making beer from scratch (all-grain brewing) or when designing recipes.


A mashing process where heating is accomplished via additions of boiling water predominantly for making ales that requires a single temperature rest for mashing.

IBU – International Bitterness Units 

The unit of measurement used in making beer to express bitterness. This is measured as milligrams of iso-alpha-acid (created when hops are boiled) per litre of beer. This is amore precise unit for measuring hops. Equal to the AAU multiplied by factors for percent utilization, wort volume and wort gravity.

Invert Sugar 

A mixture of dextrose and fructose found in fruits or produced artificially by the inversion of sucrose.

Irish Moss

A clearing agent used during the boil. It is made from a dried red marine algae known as Chondrus CrispusIs. Irish moss promotes break material formation and precipitation during the boil and upon cooling.


A clearing agent used during the fermentation process. Consisting mainly of the structural protein collagen, acts to absorb and precipitate yeast cells, via electrostatic binding. It is semi-transparent, whitish and very pure form of gelatine, prepared from the air-bladders of certain fish, originally sturgeons, now largely cod, ling and carp.


Boiling the wort with the hops added, changes (isomerises) the structure of the alpha acids so that they register a bitterness on the palate.


A vessel used in brewing in which the wort is boiled.


The step in the malting process after the germination of the grain has occurred where heat is applied to halt growth. Different levels of heat applied for varying lengths of time produce different levels of darkness in the finished malt.


The layer of foamy head that appears on the surface of the wort during the peak of fermentation.


The practice of adding a fresh actively fermenting wort to a beer that has completed its primary fermentation that induces a secondary fermentation, naturally carbonating the beer..


A beer that has been infected with lactobacillus will generally exhibit sour, tart or acidic notes to the beer flavour due to poor sanitation procedures. Some beer styles such as lambics require such an infection.


A nonfermentable sugar used to impact sweetness in beers, lactose comes from milk and has historically been added to Stout, hence Milk Stout.

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.


A class of beer made with a bottom-fermenting yeast and given a long cool fermentation. Also a term used for storing a beer for an extended period of time at reduced temperatures after fermentation to drive off yeast by-products, resulting in a “cleaner” character in the finished beer.


Lautering acts to separate the wort from grain via filtering and sparging when mashing is complete. It is derived from the German word that means “to clear”. Lautering is usually performed in a large vessel called a Lauter Tun. The Lauter Tun characteristically has either a perforated false bottom or manifold that acts as a sieve allowing the wort to drain through while holding back the spent grain as a filtrate layer.


As alpha amylase breaks up the branched amylopectin molecules in the mash, the mash becomes less viscous and more fluid; hence the term liquefaction. 

LME – Liquid Malt Extract

A liquid form of unhopped malt.


A system for classifying beer according to colour depth. It ranges from 0 for lighter colour to 500 for that darkest. The Lovibond scale is being replaced by the SRM and EBC schemes.

Lupulin Glands 

Small bright yellow nodes at the base of each of the hop petals, which contain the resins utilized by brewers.

Maillard Reaction 

A browning reaction caused by external heat where the sugar (glucose) and an amino acids form a complex product that has a role in various subsequent reactions that yield pigments and melanoidins.


Grain (normally barley, wheat, rye etc) soaked in water, germinated and then kilned to stop the growth of the grain and to reduce moisture. This modifies the grain so that sugars can be extracted by mashing.

Malt Extract

Concentrated syrup or dried powder created by drawing off and dehydrating the liquid sugar solution from malted barley.


The process of soaking, sprouting, and then drying barley (or other grain) to develop its enzyme content and render it suitable for mashing.


Also known as Corn Syrup, this substance contains a high percentage of unfermentable soluble carbohydrates that can be used as an adjunct to give beer more body and better head retention.


A natural, fermentable sugar created during mashing by enzyme activity of the available starch in a mash. The preferred food of brewing yeast. 


The process of steeping malted, cracked grain (grist) with hot water to force it to undergo enzymatic breakdown that converts starch to soluble, fermentable sugars. The term also refers to the contents of the mash.


The start of the mashing process where the water and grain are initially mixed together.

Mash Paddle

Speciality tool used to stir and mix grains during mashing to break up clumps. Generally shaped like a paddle with aeration holes in the main paddle area.

Mash Tun

A vessel used in the mashing process. Generally insulated to keep temperature at a consistent degree. 


Strong flavour compounds produced by browning (Maillard) reactions.


A term used by maltsters to refer to malted grain that has been fully modified and thus exhibits a chewy character.


The changes that take place in malting grain during the germination step resulting in the softening of the endosperm and the creation of enzymes.

Mouth feel

The fullness or thickness of a brew on the palate. Also referred to as the body of a beer.

Noble Hops

Another term for Aroma Hops.


The fragrance, aroma and bouquet of a beer.

Original Gravity

The specific gravity of wort before fermentation begins to convert the fermentable sugars. Also known as Starting Gravity


Referring to the paper, wet cardboard or sherry like aroma and flavour of beer that has reacted with oxygen.

Partial Mashing

A method of brewing used by brewers who want the simplicity of extract brewing while offering some of the flexibility of all grain brewing, but lack the equipment or time needed for full all grain brews. Partial mash brewing follows the same steps as all grain brewing, but only specialty grains are mashed with a small amount of pale malt to provide enzymes. After mashing, extract malts are added to provide the bulk of the fermentable sugars.


A scale (parts hydrogen) that measures the acidity of a liquid substance. It is a logarithmic scale that runs from 1 (very acidic) to 14 (highly alkaline). Pure water comes in at a pH of 7.


A description of a beer that exhibits band-aid like, smokey, clove like or plastic like flavours and aroma. Phenolic characteristics are necessary for some beers in small quantities but are generally an unfavourable and unacceptable addition to most beers. Phenolic flavour and aroma can be caused by excess tannin from an over sparged grain, over use of smoked grain or wild yeast infections. 


The term for the process of adding yeast to cool wort in order to commence fermentation.


Adding extra fermentable material, such as dextrose or carbonation drops to bottles prior to filling in order to perform the secondary fermentation that is required to carbonate the beer in a bottle conditioned beer.


A proteolytic enzyme which breaks up large proteins in the endosperm that would cause haze in the beer, such as commonly found in New England IPAs.

Protein Rest

A period of time that a mash is held at a constant temperature, lower than the final mashing temperature, to allow any remaining large proteins to be broken down into smaller proteins and amino acids. Performing a protein rest can reduce the possibility of obtaining a chill haze in your finished product.


The process of transferring wort or beer from one container to another in order to separate it from the sediment (trub) on the bottom of the first container. Normally this is used in relation to the transfer between a primary and secondary fermentation vessel (bottling). 


A piece of test equipment that looks a bit like a monocular that is used to determine the sugar content in your wort. It contains a complex construction of mirrors, prisms and highly polished glass. You can tell the sugar content of your wort by placing a drop of the wort on a glass sample plate, looking through the eye-piece toward a light source, you will see a reading of the sugar level. The measurements are commonly in Brix % although some also have Specific Gravity graduations as well.


Diluted wort that is extracted from the grain bed of a mash tun during the sparging process.


The conversion of soluble starches to sugars via enzymatic action.

Saccharomyces Carlsbergensis

A family of yeast strains commonly referred to as lager yeasts that generally ferment at lower temperatures (6°C – 19°C). They are also referred to as bottom fermenting yeasts.

Saccharomyces Cerevisiae

A family of yeast strains commonly referred to as ale yeasts that generally ferment at warmer temperatures (19°C – 26°C). They are also referred to as top fermenting yeasts.


The cleaning process to remove all possible containments from the equipment used throughout the brewing process.

Single Infusion

A style of mash brewing where the mash is held at a single temperature throughout the mashing process. This is the simplest method of all grain brewing.


Rinsing the spent grain with hot water to extract as much of the fermentable sugar from the grain as possible. It requires recirculation of the wort through the grain bed until the runnings are clear followed by rinsing with additional hot water.

Specific Gravity

The density of a solution as compared to water. This is measured in grams per millilitre so that 1ml of water weighs 1gram or 1.000. The scale is absolute, that is, a specific gravity of 1.050 means the liquid weighs 1.05 times as much as an equal amount of water. This measure is usually made with the use of a hydrometer. Measurement prior to fermentation is known as the Original Gravity. Measurement at the end of fermentation is known as Final Gravity.

SRM – Standard Reference Method 

A measurement of the colour of beer and malt that is similar but more accurate than the old Lovibond scale.


Also known as a Yeast Starter. A small volume of wort that yeast is added to in order to activate it prior to pitching into the main body of the brew.


Soaking malted grain in hot water to extract the fermentable sugars from the grain and dissolve them in the wort.

Step Infusion

A method of mashing that involves several rests at increasing temperatures during the process. The temperatures are attained via direct heating of the mash tun.


Same as sanitise – To eliminate all forms of life, especially microorganisms, either by chemical or physical means.

Strike Temperature

The temperature at which the water must be maintained prior to mashing-in.


It is most readily available as cane sugar and exists when the fructose molecule is joined with a glucose molecule.


A polyphenol polymer compound, with a characteristic astringent flavour, extracted from hops and the husks of barley. Tannins react with other proteins and contributes to haze formation


The layer of sediment at the bottom of the fermenter consisting of hot and cold break material (proteins), hops, and dead yeast after the fermentation process.


A vessel used to collect the wort from a mash tun.


The addition of water to a mash-in-progress from below so that the grain bed floats slightly and thus remains uncompressed. This process encourages quicker and more thorough mixing and reduces the chance of a stuck mash.

Under Modified

A term used to describe malted grain that contains fewer free amino acids and an abundance of complex proteins. This type of malt requires an additional step in the mashing process to break down the proteins in the grain known as a protein rest. Under-modified malt also has the potential to cause a protein chill haze in the finished beer. Virtually no modern malts are under-modified.


Process used to separate hops and trub from wort after boiling. Wort is stirred in a circular motion and collects in the centre of the whirlpool. Clear wort is drained from the edge. Hop additions in certain recipes will take place during this whirlpool stage.


The solution, post boil, made up of water, malt, hops and other fermentable sugars before yeast is added to ferment it into beer.

Wort Chiller

A heat exchange unit that is used to cool boiled wort to yeast pitching temperature. Wort chillers can take two general forms. The most common, an immersion chiller, is a metal coil placed into the hot wort with chilled water being passed through it to cool. The second form requires pumping the hot wort through the chiller itself while coolant fluid is pumped in the opposite direction with the two fluids being separated by either plates or tubing. The second type of chiller is more commonly known as a counter-flow chiller.


Large class of microscopic fungi, several species of which are used in brewing to convert the sugars in the wort into the beer’s alcohol content. Yeast can also impact flavours of the beer depending on style, fermentation temperature and amount pitched.


The branch of chemistry that defines thescience of brewing and fermentation.


By jase3812

I drink beer. And occasionally I'll write about it. But mostly, I drink beer.

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