Brewing Copper As home brewing becomes ever more popular in Ireland we've had increasing numbers of requests for a glossary of brewing. Many of the more technical activities in brewing are described by terms we tend not to see elsewhere in ordinary life, and several others have a meaning in brewing quite distinct from what we're used to. So, as an enhancement to the brewing chat in our Forums, and as a general reference tool, we've initiated this guide to the language of brewing.

The bulk of the initial work was carried out by Dr Jacoby, with contributions from Hendrixcat and some overview from the Editorial Team. It is intended to grow organically with the needs of the whole community, so if there's a term you think should be included, let us know in this thread.

- The Editorial Team


Acid rest
an optional rest period during the mash of between fifteen and thirty minutes where the grist is held at 35 - 40°C to acidify the mash and aid the action of malt amylases.

Adjuncts any secondary source of starches and/or sugars used in brewing, the primary source being malted barley. Adjuncts include (but are not limited to) flaked cereal grains, sugars, syrups, corn, and rice.

Aerate – the process of mixing air into wort, usually at the beginning of fermentation, to provide oxygen for the yeast.

Airlock typically a plastic water lock which allows carbon dioxide produced by yeast to escape from the fermentation vessel, while preventing the influx of outside air (which may carry infectious microbes).

Alcohol By Volume (ABV) a standard measure of how much alcohol is contained in an alcoholic beverage. It is expressed as a percentage of total volume.The ABV for a beer can be calculated based on Specific Gravity readings taken before and after fermentation using the formula: ABV = (Original Gravity - Final Gravity) X 131

For example:
(1.045-1.009) X 131= Alcohol by Volume.
0.036 X 131=Alcohol by Volume.
4.716 = Alcohol by Volume.

Ale broadly speaking, a beer brewed using a top-fermenting yeast; one that ferments best at warmer temperatures (usually between 16°C – 24°C). (Contrast with Lager). 

Alkalinity the concentration of carbonates in brewing water. Highly alkaline water requires acidification before it is suitable for mashing. Alkaline water prevents the correct pH being met during mashing, causing problems with extract and original gravity.

All-Grain Brewing the use of raw malted barley as the primary source of malt sugars in a brewing session (as opposed to the use of malt extracts). Since all-grain brewing requires mashing and sparging, it is considered the most "advanced" form of home brewing. (Contrast with Kit Brewing and Extract Brewing). See also this guide to all-grain brewing .

Amylase malt enzyme responsible for the breakdown of malt starch into simpler sugars during mashing. 

Alpha Acids  acids present in hops which are isomerised during the boil into isoalpha acids.

Alpha Acid Units (AAU) – the amount of bitterness in hops. Low alpha acid hops are in the 2% – 5% range; high alpha hops are in the 9% and over range. Brewers also measure hopping volumes in IBUs (International Bittering Units). IBUs tell how bitter the beer is, whereas AAUs tell how bitter the hops themselves are.

Aroma Hops – hops added near the end of the boil in order to extract and preserve their delicate aromatic oils. 

Attenuation – the extent to which yeast converts sugar to alcohol and CO2.

Autolysis the tendency for yeast to feed on each other after fermentation finishes, releasing unpleasant aromas and flavours into the beer. For beers which will remain in the fermenter for an extended period of time (more than 2-3 weeks), the potential for autolysis can be reduced by using a secondary fermenter to reduce the amount of sediment present.

a syphon tube with a built-in pump to deliver the suction needed to start the syphoning process. Autosyphons do not require the user to physically suck on the end of the tube (as is the case with a simple syphon), and so are less likely to be a source of infection.    


Ball lock the most common type of keg fitting used on corny kegs for the liquid and gas connections. The quick-disconnect locks onto a groove in the keg fitting using a spring-loaded collar, and small steel ball bearings.

Barley – the grain that provides the most common source of fermentable sugar in beer.

Base malt the malt that contributes the majority of fermentable sugars in the grist. (Contrast with Speciality Malt)

Batch priming the practice of adding the full quantity of priming sugar for a batch of beer to the bottling bucket prior to bottling. This can be contrasted with the method of priming each bottle individually with an equal quantity of priming sugar.

Batch sparging a method in which the mash tun is first completely drained of wort, then an additional amount of hot liquor is infused into the mash tun, stirred to help dissolve more extract and then drained again into the brewpot. (Contrast with Continuous sparging).

Beer kit – see Kit brewing

Bench capper – see Bottle Capper.

Bittering Hops hops added at the beginning of the boil and provide the bitter flavour to beer. (Contrast with Aroma Hops).

Blow-off-tube – a tube (one side of which is inserted into a fermenter and the other submerged into a bucket of water) which allows for the release of carbon dioxide and excess fermentation material.

Body – refers to the fullness or mouthfeel of a beverage. In beer, body is the result of residual malt sugars, dextrins and alcohol.  

Boiler the vessel, usually plastic or stainless steel, in which you boil your beer to prepare it for fermentation. Smaller brewpots can be used on a normal kitchen stove top. Larger vessels may require the installation of heating elements or the use of a gas burner to bring the liquid to a rolling boil. Also known as a Copper or a Kettle.

Boiling time the period during which wort is boiled. Generally one hour is sufficient. The boil must be vigorous and rolling to maximise utilisation of hop alpha acids, good break formation, sterilisation of the wort and removal of volatiles in steam. An evaporation rate of 10% per hour indicates that the boil is vigorous enough.

Bottling wand a device which allows beer bottles to be filled with minimal splashing, thereby reducing aeration/oxidation of the finished beer.  A typical bottling wand consists of a rigid plastic tube long enough to reach the bottom of the bottle, and a valve which is opened by pressing the tip of the filler against the bottom of the bottle.  Can be attached directly to the end of a siphon hose, or to the spigot of a bottling bucket. See also this guide to bottling beer

Bottle capper a device for crimping metal caps onto beer bottles. The two most common bottle cappers are the hand-held, double lever type, and the somewhat more expensive bench capper. See also this guide to bottling beer

Bottle conditioning – a method of carbonating bottled beer by adding a small amount of extra sugar (see Priming) at the point of bottling. The residual yeast creates carbon dioxide under pressure, carbonating the beer.

Bottling bucket a vessel from which beer is syphoned off and placed into bottles. Generally beer is racked from a fermenter into the bottling bucket, leaving behind unwanted yeast matter. A fixed amount of priming sugar is added before bottling to provide carbonation through the action of the entrained yeast. See also this guide to bottling beer

Break material – see Cold break and Hot break.

Bung in brewing, an apparatus (usually rubber) used to seal a fermentation vessel. Unlike a lid, which encloses a container from the outside, a bung is partially inserted inside the container to act as a seal. Bungs can also be purchased bored to allow an airlock to be fitted to a fermenter. 

Brew belt an electric heating belt which can be wrapped around a fermenter.

Brewpot – see Boiler.

Brix unit of measurement of sugar in wort. Functionally equivalent to degrees Plato



Calcium – an essential component in brewing liquor. Essential for good mashing, break formation, fermentation and clarification. Values of between 50 and 150 ppm are common.

Calcium Chloride – a source of calcium in brewing water. Chloride provides fullness to the mouthfeel of beer. Should be balanced with sulphate.

Calcium Sulphate – see Gypsum

Caramel malt – see Crystal Malt.

Carbonation – the concentration of carbon dioxide gas present in beer. Expressed in volumes of carbon dioxide, and generally between 1 and 5 volumes, depending on the beer style. Determined by the amount of sugar used when priming.

Carboy – a fermenter with a large body and narrow neck, the advantage of which is minimal surface area exposed to air contact (which can lead to oxidation and infection). Carboys come in glass and plastic varieties, glass being the preferred alternative due to the fact that they are less susceptible to infections and less permeable to air. Each variety is available in several sizes, the standard size being 5 gallons (25L).

Cask-conditioned beer – see Real Ale.

Chill haze  haze that forms in beer upon chilling. Very common in home brewed beer and Real Ale due to a lack of filtration. The haze disappears upon warming and does not generally appear above 10 C. Caused by the interaction of tannins and protein.

Clone recipe a recipe that purports to clone a commercially brewed beer.

Cold break refers to the proteins that precipitate out of the wort when it is rapidly cooled after the boil has come to an end. If the wort is not cooled rapidly, the proteins will remain in the beer and may cause Chill haze. (Contrast with Hot break).

Continuous hopping the constant addition of hops to wort during the boil, in contrast to the more traditional batch addition of hops at specific times. Best typified by the 120 minute IPA brewed by Dogfish Head Brewery, Delaware USA.

Continuous sparging – a method in which water is continuously introduced to the top of the mash, usually with the aid of a sprinkler system.  This water then percolates down through the grain bed increasing in sugar concentration as it goes. The goal is to gradually replace the wort with the water, stopping the sparge when the gravity is 1.008 or when enough wort has been collected, whichever comes first. This method demands more attention by the brewer, but is generally considered the most efficient sparge method. (Contrast with Batch sparging). 

Copper – see Boiler.

Crystal malt  one of the three main categories of brewing grains. Crystal malts are created by the maltster by steeping wet grains to achieve the production of sugars within the whole grains. When the grains are then dried and heated in kilns, the sugars are crystallised and caramelised to varying degrees of darkness. Since crystal malts do not require mashing, they may be used by extract and all-grain brewers alike.

Clarify – to remove haze-causing particles and solids out of solution, often with the help of finings. Clarification is primarily a cosmetic process since haze-causing particles usually have no effect on flavour.

Cold break – proteins that coagulate and fall out of solution when the wort is rapidly cooled prior to pitching the yeast.

Conditioning – the residual activity of the yeast following primary fermentation, which helps to refine the flavour of the beer.

Cornelius keg (aka corny keg)  a tall, skinny stainless steel keg, typically 5 gallons in capacity, manufactured by the Cornelius company. Probably the most popular system for kegging homebrew.

Corn sugar see Dextrose.

Corny keg see Cornelius keg.  

Craft brewing – a newer, less common term for "microbrewed" beer. Craft breweries generally produce all-malt beers from quality ingredients, emphasising flavour and individuality rather than industrial cost-cutting measures and marketing gimmicks.


Decoction a mashing technique classically employed by lager brewers due to the use of under modified malt.  Malt is held at a number of rest periods to aid efficiency during the mash. Increases in mash temperature are achieved by removing a portion of the mash, boiling it and returning it to the mash tun where it raises the temperature of the entire mash to the next pre-set mash temperature. The process can be carried out over a number of steps.

Demijohn a one-gallon glass jar with straight shoulders and two handles at the top. They are often used for smaller experimental batches of beer.

Dextrose glucose monohydrate. Can be used as a priming sugar.

Dimethyl Sulphide Commonly referred to as DMS. A pungent sulphur compound considered an off flavour if found in high concentrations in ales, but acceptable in low concentration in lagers. Stems from lager and pale malt, but is generally driven off in steam during the boil. Has been described as smelling like cooked corn, rotten cabbage or cat's urine, depending upon the concentration.

Dip tube – a tube, usually made from metal, which extends from a fitting on the top of a keg, down into the body of the keg.  On a standard soda keg, the dip tube on the "out" fitting extends all the way to the bottom of the keg, allowing beer to be drawn off.  The dip tube on the "in" fitting is short, and is used to inject CO2 into the headspace.

DME abbreviation for "Dry Malt Extract" (sometimes referred to as "spray malt"). See Malt.

DMS – see Dimethyl sulphide

Doughing-in the process of adding the grist to the strike water.

Dry-hopping – the addition of hops during or after primary fermentation to boost the hop aroma of the beer.


Efficiency the percentage of available extract that is retrieved from malt during mashing. Home brewers can expect around 75% efficiency with the most common mashing methods employed.

Enzymes  -- see this article about understanding enzymes in brewing .

Ester – a fermentation by-product that contributes fruity characteristics to the aroma and flavour of the beer.

Extract brewing - the use of malt extract as the primary source of malt sugars in a brewing session (as opposed to using raw malted barley grain). Malt extract comes in two varieties: a dry powdered extract (known as dry malt extract or 'DME') and a thick liquid extract (known as liquid malt extract or 'LME'). Each variety may be purchased pre-hopped, for extra flavour, or unhopped, giving the brewer greater control over the final product. (Contrast with All-Grain Brewing). See also this guide to extract brewing .


False bottom a raised perforated platform in a mash/lauter tun, designed to allow for drainage of sweet wort during the sparge while retaining the grain bed. False bottoms range from fitted metal screens to perforated plastic domes to simple mesh bags.

Fermentation – the process by which yeast converts sugar to alcohol and carbon dioxide.

Fermentation lock – see Airlock.

Fermenter – the vessel into which you add the wort and yeast to ferment into beer.

Final Gravity  the measure of the Specific Gravity of the beer after it has finished fermenting.

Finings – gelatinous products added to the boil to brighten and clarify the beer. Irish moss (a type of seaweed) is a classic example.

Finishing hops – see Aroma Hops.

First runnings the heavy, sugar-laden liquid which comes out of the mash tun first, before sparging.  In a parti-gyle scheme, the first runnings are used to brew a very strong beer (e.g. a Barleywine), while the second runnings are used for a lower gravity beer.

First wort hopping The addition of hops directly to the kettle as the first runnings are added before the boil commences. Proponents suggests that a more favourable bitterness in acheive with this method.

Flocculation the tendency of yeast to clump together and fall from solution when fermentation is complete. Extent and timing of flocculation is often yeast strain specific.

Force carbonating – carbonating beer by applying CO2 under pressure. This is typically achieved in corny kegs, but may also be done in plastic soda bottles, with the proper fittings (e.g. carbonator cap).  By force carbonating, the beer can be drinkable as soon as it finishes fermenting and falls clear, rather than having to wait 1-2 weeks for natural carbonation to develop after priming.

Fruit press – a device used to separate fruit solids (such as stems, skins, seeds, pulp, leaves, and detritus) from fruit juice. It is typically used in cider-making.

Fusel alcohols
– larger alcohol molecules other than ethanol produced by yeast during sub optimal fermentation conditions. Also referred to as 'higher alcohols', they cause off flavours best characterised as 'hot'.


Gas burner  a popular device, especially in the US, for heating hot liquor tanks and brewpots. Less popular in Ireland, however, due to the fact that they must be used outdoors. (Contrast with Heating Element).

Grain bag a fine mesh bag, usually made of nylon or cotton.  Typically used by extract brewers to steep specialty grains in the brewing water.

Grain bed depth the depth of grain in the mash tun. The bed depth dictates the speed of wort run off and the likelihood of a stuck mash.

Grain bill – a list of the types and quantities of malt and other grains used in a beer recipe.

Grain mill  a device used to crack open grain, providing access to the starch within. The extent of milling is significant. Too little and the starch cannot be accessed. Too much and there will be insufficient husk to provide an effective filter bed for wort run off.

Gravity – the concentration or density of malt sugar in the wort. The higher the concentration of sugar in a beer the higher the gravity. The term has three central uses in homebrewing: specific, original and final. Specific gravity is the measure of the density of beer compared to the density of water. Original gravity is the density of the beer before it ferments. And final gravity is the density of the beer after it has finished fermenting.

Green Beer – immature beer containing a number of fragrant flavour compounds that are eliminated from the beer during maturation.

Grist – in all-grain brewing, "grist" refers to the mixture of crushed grains (and adjuncts, if they are used) which form the raw material for the mash. Mashing begins when the strike water is mixed with the grist.

Growler – glass jug, typically 1/2 gallon capacity. Commonly used by brewpubs and micro breweries in the US to sell fresh draft beer for carry-out.

Gypsum calcium sulphate. A source of calcium when added to brewing liquor. Also a source of sulphate, which enhances hop crispness.


Head retention the ability to hold a layer of foam on top of the beer.  A beer with good head retention will maintain some residual foam until the beer has been completely consumed, leaving "lacework" down the sides of the glass.

Headspace the area at the top of a vessel (fermenter, bottle, or keg) which does not contain any liquid.  In general, the goal is to minimize headspace, to prevent oxidation of the beer by oxygen in the air.  Headspace in the primary fermenter is not a serious concern, because the CO2 produced by fermentation forms a protective blanket on top of the beer, and forces nearly all of the oxygen out of the fermenter.

Heat Exchange Recirculating Mash System commonly abbreviated as "HERMS".  A mashing system in which the mash temperature is controlled by circulating the liquid part of the mash through a heat exchanger.  The main difference between a HERMS and a RIMS system is that in a HERMS system, the wort never comes into direct contact with the heating element. This supposedly results in less scorching, and a cleaner-tasting wort. (Contrast with RIMS). 

Heating Element – an electric element attached to the inside of a hot liquor tank or brewpot for heating and boiling the liquid. (Contrast with Gas Burner). 

HERMS see Heat Exchange Recirculating Mash System

High alpha hops hops which contain a high percentage of alpha acids (the cut off is generally considered to be around 9%).  High alpha hops are typically used for bittering rather than finishing, since the high alpha acid content means that less hops are needed to produce a given level of bitterness, and they also tend to have less refined flavour and aroma characteristics.

Homebrew kit a starter kit containing the basic equipment necessary for brewing beer. A good kit should include at least the following: a 25L fermentation vessel, a 25L secondary fermentation vessel or bottling bucket, thermometer, airlock, bung (usually bored), trial jar, bottling wand, hydrometer, bottle brush, syphon, large non-wooden spoon, bottle capper, crown caps and some steriliser. Distinct from a beer kit used for kit brewing.

Hop bag – a mesh bag for hops that can be submerged in the brewpot (or the fermenter, in the case of dry hopping). Hop bags are useful in helping to minimise the spread of hop sludge, especially in relation to pellet hops which have a tendency to completely disintegrate in liquid. However, hop bags can also reduce the efficiency with which hop bitterness, flavour, and aroma is extracted.

Hop oil the aromatic fraction of hop compounds. Provides aroma and flavour. They are volatile and easily driven off in steam if added too early in the boil.

Hop Pellets whole leaf hops that have been shredded and compacted into pellets. Forms included type 90 and type 45, in which 10% and 55%  respectively of extraneous hop matter has been removed. Fewer hop pellets are required for a given volume of whole leaves. Also hop oils are more readily accessible due to damage to lupulin glands.

Hop strainer a slotted pipe or manifold attached to the inside of the outlet tap on a brewpot to allow the wort to be drained off while leaving behind the hop sludge.

Hops Humulus Lupulus, Cannabinacea family. The hops used in brewing are the flower of a tall-growing vine of the same name. The green buds are covered with lupulin glands, tiny sacks containing acids and aromatic oils which provide the bitterness and aromatic qualities for which hops are so highly prized. Along with balancing the flavour of beer and enhancing its aroma, hops act as a preservative by inhibiting many potentially spoiling organisms. They can generally be purchased as whole leaves or in compressed pellet form.

Hot break – proteins that coagulate and fall out of solution during the wort boil. The hot break appears as a vigorous layer of foam that quickly recedes. It can sometimes cause a ‘boil over’ if the brewpot lacks sufficient head space. Contrast with Cold Break.

Hot liquor tank a vessel designed to bring water to strike temperature for mashing. In a three-tier set-up, the hot liquor tank occupies the top level.  

Hot-side aeration a much debated process in brewing. Hot wort readily takes up oxygen when aerated. This can result in the development of off flavours in the finished beer through oxidation of wort constituents.

Husk the shell around a barley kernel. It is a rich source of polyphenols and silica and is essential for good run off from infusion mash tuns.

Hydrogen Sulphide a pungent gas produced by yeast during the early stages of fermentation. It smells of rotten eggs and is driven off my carbon dioxide production during fermentation leaving little trace of it in the finished beer. It can also be produced in larger quantities by unwanted contaminating bacteria. Hydrogen sulphide of bacterial origin often persists into the finished beer.

Hydrometer – a graduated glass instrument for measuring the specific gravity of a liquid. Hydrometers are particularly useful for estimating the alcohol content of a beer and for monitoring the progress of fermentation.


IBU  see International bittering unit.

Immersion chiller  see Wort Chiller.

Infection the presence of micro organisms in sufficient numbers, other than the pitched yeast strain, to taint the beer with off flavours. See Wild Yeast

Infusion mash The process of mashing in which no addition heat is added to the mash tun during mashing. The strike water is adjusted to a temperature that will allow the mash to settle out to a desired temperature of between 65 - 68 C once the malt is added. (Contrast with Decoction).

International bittering unit (IBU) – part per million of alpha acids present in beer. Calculation can be hard to do accurately because of great variations in hop utilisation between brewing equipment. (Contrast with Alpha Acid Unit). 

Irish moss – a seaweed commonly used as a clarifying agent in the brewing process. A small amount is boiled with the wort, attracting proteins and other solids, and then removed from the mixture after cooling.

Isinglass – a beer clarifier made from the swim bladders of certain fish. Like gelatin, it causes yeast to settle out more rapidly. Isinglass is the traditional clarifier for British cask ales, and is added at the end of fermentation.

Iso Alpha Acids the form that alpha acids take after isomerisation during the boil. They provide the bitterness in beer.

Isomerisation a chemical process in which a molecule is rearranged in structure, but still contains the same number of atoms.


Keg conversion any DIY project for converting a 10 gallon stainless steel keg into a hot liquor tank, a mash tun, or a brewpot. Typically, this involves removing the lid of the keg with an angle-grinder and drilling holes near the bottom for an outlet tap and heating elements (using stepped drill bits or hole saws). Welding is sometimes used to fix the tap and elements into place, but this is not strictly necessary.   

Kegerator a draft beer dispensing device intended for residential use. A keg is placed in a fridge with a special temperature control system and then connected to a tap on the outside which can dispense draught beer. The user is able to maintain a tapped keg in such a device for extended periods of time, usually a couple of months, without losing any quality in the taste of the beer.  

Kilning – the heating of malt to reduce the moisture content and impart colour and flavour. The temperature at which kilning is carried out, and the length of the kilning, determines how dark the malt will be.

Kit brewing – the simplest form of brewing and the most popular starting point for the novice brewer. Kit brewing involves the use of malt extract (usually liquid malt extract which has been pre-hopped) as the primary source of malt sugars in a brewing session. This liquid is usually boiled with some sugar (preferrably spraymalt) and topped up with a predetermined amount of water in the fermenter. Yeast (which is often supplied with the kit) is then added to start the fermentation process. (Contrast with All-Grain Brewing.) See also this guide to kit brewing .

Krausen (kroy-zen) – the fluffy foam that grows on top of wort as it begins to ferment. The krausen can sometimes clog airlocks, in which case a blow-off tube may be required to release the excess foam.

Krausening – refers to the addition of freshly fermenting wort (i.e. wort with a krausen) to a previously fermented batch just before it is bottled. Krausening will carbonate the bottled product.


Lag time – the period between the pitching of the yeast into the wort and the first noticeable effects of fermentation (e.g. when the airlock starts to bubble as the CO2 builds up in the fermenter). 

Lager – broadly speaking, beer brewed using a bottom-fermenting yeast; one that ferments best at cooler temperatures (usually between 7° – 15°C). Lager beer is characterised by a lack of esters, maltier flavour, and high clarity.(Contrast with Ale). 

Lagering derivative of the German word for storage. Beer is stored at a low temperature for weeks or months during which time maturation occurs through the elimination of undesirable flavour compounds. See Green Beer.

Lambic – the speciality beer of Brussel, made using spontaneous fermentation by wild yeast. Renowned for its sour flavour. Usually blended with batches of different ages to make Gueuze, or with fruit juice to make Kriek (cherries), Frambois (raspberries), etc.

Lauter tun – any vessel used to hold all-grain brewing ingredients during the sparge. Lauter tuns must contain a false bottom or manifold to allow drainage of sweet wort while retaining the grain bed. However, anything from a brewpot to nested plastic buckets will do, provided there is a way to strain the wort off while leaving the grain behind. Many lauter tuns are equipped with sprinklers above the grains to allow an even spray of sparge water over the grain bed. Many homebrewers use a combined mash tun/lauter tun set-up, but strictly speaking they are not identical. A mash tun is a device for mashing grain, whereas a lauter tun is a device for separating wort from grain.  

Lipids – fats and oils stemming from malt and hops. Lipids reduce foam retention and cause off flavours if present in high concentration.

Liquor – also known as strike water. In all-grain brewing, "liquor" refers to the hot water mixed with the grist to begin the mashing process. Liquor must be adjusted to specific temperatures to achieve the appropriate mash-in temperatures for different mashing styles.

LME - abbreviation for "liquid malt extract". See Malt.

Lovibond – a measurement scale used to specify the colour of malt. The higher the number, the darker the malt. Most base malts have a Lovibond rating below 10 (dark Munich malts may be slightly higher). Crystal/caramel and toasted malts generally have a Lovibond rating of between 10 and 100. Roasted malts are typically above 400.

Low alpha hops – hops with a low alpha-acid content (typically between 2 - 5%). Many of the preferred varieties of finishing hops are low alpha, though there are exceptions.


Maillard Reactions complex chemical reactions that occur during kilning of roasted malt. Rich and flavourful compounds are formed during kilning from the interaction of malt sugars and proteins.

Maltin brewing, the noun "malt" generally refers to the sugars extracted from malted cereal grains (usually barley or wheat). Malt is available commerically as a concentrated syrup or powder that many homebrewers reconstitute to create their wort (this is commonly called "malt extract"). Malt is also the term for the malted grains all-grain brewers use to extract their wort sugars.  

Malted barley barley grain that has undergone a process in which the raw grains are soaked, allowed to germinate (sprout), heated, and then dried. This process is undertaken by malting companies, commonly known as "maltsters." Malting stimulates the creation of enzymes crucial to mashing and begins the process of chemical breakdown necessary to create sweet, fermentable wort from raw grains. Various malting techniques create the three major categories of malted grains: base or pale malt, crystal or caramel malts, and roasted malt.  

Maltster see Malted Barley.

Manifold a device used at the bottom of a lauter tun to strain the wort from the grain. Manifolds are commonly constructed from copper or plastic tubing, connected in a flat ring or "H" shape, into which holes or slots have been cut. The tubing is attached to a fitting which passes through the wall of the lauter tun, to allow the wort to be drawn off. 

Mashing the first major phase of all-grain brewing (before sparging). It involves a hot water steeping process designed to hydrate the malted grain, gelatinise its starches, release its natural enzymes, and convert the starches into fermentable sugars. The malt is crushed to facilitate hydration and infused with pre-heated water to achieve a temperature between 65 and 68°C (this range is flexible and depends upon the style of beer being brewed). The mash is typically held at that temperature for an hour, then drained of wort.. It is then infused with an equal volume of sparge water, stirred, allowed to settle, and drained once again. The goal is to extract as much of the sweet wort from the grain as possible.

Mash tun any vessel used to hold all-grain brewing ingredients during the mash. Mash tuns range from simple brewing kettles and cooler boxes, to combination mash/lauter tuns equipped with false bottoms, heating devices and sprinkler systems. An effective mash tun should be capable of maintaining a steady temperature throughout the duration of the mash and be designed in such a way as to allow for the efficient extraction of wort (if it is designed to double-up as a lauter tun). See this guide to building a mash tun using a picnic coolerbox

Mini mash The process of carrying out a small volume mash to produce wort that is supplemented with malt extract. It is often seen as an intermediate step between extract brewing and all grain brewing, but the logistics of carrying out a small volume mash are much the same as full one, providing vessels of suitable size are available.

Modification a process in malting during which protein in barley kernels is broken down into simpler fractions, more readily used by yeast.

Mouthfeel the sensation of fullness in the mouth created by dextrins and proteins in the beer. See Body. 

Munich Malt malt kilned at a slightly higher temperature than pale malt but for a shorter period of time. Imparts sweetness and roundness of flavour.



Noble hops hop varieties prized for their quality flavour and aroma. Generally used for late hopping because of very good aroma properties, but also because they tend to be low in alpha acids and not well suited to bittering. Types include: Saaz, Hallertau, Mittelfruh.


Off-flavours undesirable flavours present in beer stemming from problems in the brewing process.

Original gravity the measure of the Specific Gravity of the beer before it ferments.

Oxidation the action of oxygen on malt constituents in beer, often undesirable.


Pale malt also known as base malt. The most common form of malt used in brewing. Typically kilned at a temperature of 80 C. Commonly used varieties include Maris Otter, Optic and Pearl. (Contrast with Speciality Grain).

Parts per million a common measure of components in solution. Equivalent to milligrams per litre.

Parti-gyle the process of producing two distinct beers from a single mash. Typically a high abv beer is produced from the stronger first wort from the mash tun, followed by a lower abv beer fermented from the weaker second wort.

pH the concentration of hydrogen ions in a solution, determining acidity/alkalinity. pH values range from 0 to 14. Pure water has a pH of 7. Mashing is carried out at around 5.2 and finished beer has a pH of around 4.5. The correct pH is essential in the various brewing steps and must be met to ensure good quality beer production.

pH stabiliser  a chemical used to bring about a desired pH. Most commonly used to ensure a pH of around 5.2 for effective mashing.

Phenol potent off flavour caused by infection with wild yeast. Smell of antiseptic, classically TCP.

Pitching – the adding of yeast to cooled wort to initiate the fermentation process.

Pitching rate the amount of yeast required for a given original gravity of wort to ensure good fermentation.

Plato a measure of sugar in malt as a percentage of sugar by weight. E.g. 10 Plato equates to a 10% sugar solution. 1 degree Plato is equal to a specific sugar gravity of 1.004. Plato is widely used by brewers on the continent. Specific gravity readings are more common in Ireland, the UK and the USA.

Polyphenols  see Tannins. Not related to Phenol.

Poppet – a small, spring-loaded valve located inside a soda keg fitting. The poppet seals the fitting when the hose fitting is removed. Poppets are the most likely source of leaks on older soda kegs; replacements are available from various on-line vendors.

Primary fermentation the initial and main metabolic process carried out by yeast in the production of beer. Primary fermentation starts shortly after yeast is pitched into cooled wort. (Contrast with Secondary Fermentation).

Priming the practice of adding a small quantity of sugar to the beer at bottling time to allow bottle conditioning to occur. Prior to such conditioning, the yeast count in the beer needs to be reduced to around 500,000 cells per millilitre in conditioning tanks. The remaining yeast then ferment the newly added sugar thus providing carbonation to the beer.

Priming sugar sugar (often dextrose or glucose) used to carbonate beer in the bottle.

Protein rest an optional rest period during mashing lasting 20 - 30 minutes at a temperature of 45 - 60 C during which large protein molecules are broken down into simpler fractions providing nutrients for yeast and aiding stability of the finished beer. Generally not required if well modified malts are used.


the mechanism which allows keg fittings to be connected and disconnected quickly and easily. Consists of a keg fitting on the keg itself, and a mating connector on the gas or beer line to be connected to the keg.  When the quick-disconnect is not connected, spring-loaded valves in the keg fitting and connector prevent any liquid or gas from flowing. When the quick-disconnect is connected, the mechanism causes both valves to open.



– The process of transferring liquid from one container to another, usually with a syphon.

beer from Bamberg brewed using rauchmalt.

Rauchmalt malt that is dried over a fire of moist beechwood. The malt becomes infused with the smoke producing a distinct smoked flavour to the finished beer.

RDWHAHB acronym for "Relax, Don't Worry, Have A Homebrew", a phrase popularised by Charlie Papazian in his classic book the New Complete Joy of Homebrewing.

see Siphoning.

Real Ale
a term devised by the UK's Campaign for Real Ale (CAMRA) designating beer brewed from traditional ingredients, matured by secondary fermentation in the container from which it is dispensed, and served without the use of extraneous carbon dioxide. Real ale may be cask-conditioned or bottle-conditioned ("Real Ale In A Bottle", RAIAB). 
Recirculating Infusion Mash System
commonly abbreviated as RIMS.  A mashing system in which a pump is used to continuously recirculate the liquid part of the mash through the mash bed.  Mash temperature is maintained by passing the liquid over a heating element. The heating element is cycled off and on to maintain the desired mash temperature.

the process of transferring wort, without overt aeration, from the bottom of the mash tun to the top of the grain bed where it drains through the bed, being clarified of larger pieces of matter as well as polyphenols and lipids.

optical device used to estimate the concentration of sugar in wort. Measures in degrees Brix which are functionally equivalent to degrees Plato.

a device which is used to reduce the pressure of CO2 coming from a tank (typically around 800 PSI) to the pressure required to carbonate or dispense beer (typically 5 to 30 PSI).

Reinheitsgebot German beer purity law, which was originally enacted in Bavaria in the year 1516, spreading to the rest of Germany in the 19th century.  The Reinheitsgebot states that beer may only contain water, malt, hops, and (once it was realised that they play an essential role), yeast.

Relief valve a pressure-activated valve, which protects against dangerous over-pressurisation in a system or device.  If the safe working pressure is exceeded, the relief valve "vents", releasing the excess pressure.  The most common types of relief valves seen by homebrewers are on CO2 regulators, and soda kegs.

Residual extract – the sugar left over after fermentation. This includes the sugars that brewers' yeast was unable to ferment. It provides sweetness and body to the finished beer.

RIMS – see Recirculating Infusion Mash System.

Roasted barley
 – unmalted barley kilned to very high temperatures. Widely used in stouts to provide black colour and sharp roasted flavour.

Roasted malt – malt that is heated to very high temperature in a kiln (in excess of 200 C). Chemical process called Maillard Reactions produce rich, complex flavour compounds that typify the roasted flavours found in stouts and porters. (Contrast with Pale Malt).


Second runnings – the lighter, more dilute runnings which come out of the mash tun after the addition of sparge water.  In a parti-gyle scheme, the first runnings are used to brew a very strong beer (e.g. a Barleywine), while the second runnings are used for a lower gravity beer.

Secondary fermentation – a slower fermentation process following the vigorous primary fermentation. Beer is removed from the primary fermentation vessel and placed into a second vessel, leaving behind dead yeast and trub matter.  There is debate over its efficacy for regular strength beer, but it is recommended for stronger beers that require a long maturation period. (Contrast with
Primary Fermentation). 

Session beer – a moderate strength beer which can be consumed in larger quantities due to its low alcohol content.

Siphon/Siphoning – the gravity-powered act of transferring beer from one container to another, or the equipment used to do so. Some brewers refer to syphoning as "racking".

Smack-pack – a method of yeast culturing employed by Wyeast. A pack contains yeast along with a pouch of yeast nutrient. Pressure is applied to the pack which ruptures the inner pouch, mixing the yeast with the nutrient, allowing the yeast to propagate within the pack. The pack swells as the yeast multiply, at which point the yeast can be pitched into cooled wort or transferred to a further propagation step.

Smoked malt – see Rauchmalt.

Sparge arm – a rotating sprinkler arm attached to the inside ceiling of a lauter tun. Provides a fine misting spray to rinse the wort from the grain. 

Sparging – the process at the end of mashing during which residual sugar retained in the mash is rinsed from the grain with hot water (typically no hotter than 80 C) and run to the brewpot for boiling.

Speciality grain – malt and grain that makes up a minority of the grist, but adds substantial flavour and colour to the finished beer. (Contrast with Base Malt).

Specific Gravity - the measure of the density of beer compared to the density of water.

Spray malt – see Malt Extract.

Starch – a complex sugar present in malt and grain that is converted to simpler sugars during mashing.

Steeping – in home brewing, the process of soaking speciality grains in hot water to extract flavour and colour. Conversion of malt starch does not generally occur and the rich solution is added to malt extract for boiling.

Stopper – see Bung.

Strike water – the water mixed with the grist to initiate mashing.

Stuck fermentation – occurs in brewing when the yeast die prematurely or become dormant before fermentation has finished. A stuck fermentation is an unintentional and unwanted occurrence that can lead to beer being spoiled by bacteria and oxidation. There are several potential causes. The most common are extreme temperatures (too cold and the yeast will become dormant; too hot and the yeast will die) and deficient nutrient levels in the wort. Once the fermentation is stuck, it can be difficult to restart due to a chemical compound released by dying yeast cells that inhibit the future growth of yeast cells in the batch.

Stuck mash – see Stuck Sparge.

Stuck sparge – in all-grain brewing, the inability to get any liquid to flow through the grain bed during the sparge. Generally only an issue with mashes containing a high percentage of wheat, or unmalted adjuncts.  Rice hulls can be added to the mash to reduce the risk of a stuck sparge.


– complex compounds found in beer stemming from malt and hops. Can cause haze in beer, particularly when beer is chilled. See Chill Haze.

Three-tier brewing system 
– a brewing system consisting of three vessels seated on three ascending platforms. The system is designed to allow liquid to flow from one vessel to the next by gravity alone. The uppermost platform houses a hot liquor tank, the middle platform a mash tun, and the lowest platform a brewpot. The hot liquor tank and brewpot can be heated by gas burners or by electric elements. 

Torrified wheat wheat which has been heated, causing the endosperm to expand and pop. This gelatinises the starch in the grain rendering it instantly accessible (i.e. water soluble without the need for a extra 'cooking'). Torrified wheat does not therefore need to be mashed. It is generally used whenever head retention is desired when brewing bitters.

Trial jar a tall, slim vessel used to hold a sample of wort during gravity estimation using a hydrometer.

Trub  see Hot Break and Cold Break.


Vorlauf -
see Recirculate.


Whirlpooling the practice of spinning the wort in a circular motion in the kettle, after the boil is complete.  This causes the trub and spent hops to pile up in the center of the kettle, allowing relatively clear wort to be drawn off from the side.

Whole-leaf hops
hops as they appear on the plant. Brewers use kiln dried whole leaves during the brewing process. (Contrast with Hop Pellets).

Wild yeast yeast naturally present in the environment. Generally undesirable in beer except in those styles that specifically require fermentation by wild yeast. (See Lambic). They produce potent off flavours, most typically phenolic notes. They can ferment complex sugars that brewers yeast cannot, often resulting in below expected final gravity. Classic examples include Saccharomyces diastaticus and Brettanomyces.

Wood chips roasted chips (often American or French oak) are sometimes added to a secondary fermenter to impart a range of flavours typical of beer that has been conditioned in wooden barrels or casks. 

the sweet, rich fluid produced during mashing. It is a complex solution of sugars, protein, fats, and inorganic minerals. It is boiled, usually for an hour, during which time hops are added to provide bitterness and extra flavour and aroma.

Wort chiller a device used to rapidly cool wort from boiling to pitching temperature. Can take the form of an immersion chiller (commonly a copper coil which is submerged in the wort and pumped with cold water), or a counter flow chiller (which pumps hot wort through piping that runs against a separate cold water pipe). In each type, heat is transfered from the hot wort to the water, cooling the wort. See also this guide to building an immersion wort chiller . 


Yeast single-celled ascomycetous fungi used to ferment beer. Brewing yeast strains differ from bread yeast in that they are selected for their tolerance to alcohol, their tendency to attenuate and flocculate, and the flavour characteristics they impart in fermentation. Yeast is a good source of Vitamin B, which is why Brewer's Yeast (dead) is often sold in health food stores.

Yeast nutrient -
a mixture of various nutrients, minerals, and dead yeast ("yeast hulls" or "yeast ghosts") which provide the materials necessary for yeast to reproduce and ferment vigorously. Nutrients are helpful in almost any batch of beer, and are usually required in low-nutrient styles like mead.

Yeast starter - a method employed to ensure that a sufficient amount of yeast is cultured to meet the required
pitching rate for a given original gravity of wort.


Zymurgy - the science of brewing and fermentation.

Discuss this item in the forums.