Welcome to the Glossary of Beer Terms at Brewpedia, a definitive resource for both newcomers and seasoned enthusiasts in the world of beer and brewing.

This comprehensive guide provides clear explanations of key terms, techniques, and concepts, offering an in-depth understanding of the craft.

From the basic elements of brewing to the nuanced language of beer tasting, our glossary serves as an essential reference for anyone seeking to deepen their knowledge and appreciation of beer.

Acetic acid

Acetic acid is an acid frequently produced by various yeasts and bacteria. It's a dominant off-flavour that emerges from the growth of acetic acid bacteria in beer, characterised by its vinegar-like aroma and taste. These bacteria convert ethanol to acetic acid, leading to this distinct flavour.

Acid washing

Acid washing is a technique to sanitise yeast from potential bacterial contamination. It involves submerging the yeast in an acidic solution with a pH around 2.2 just before the onset of fermentation. Yeast cells tend to be more resistant to acid than bacteria, resulting in the latter's elimination.


Adjuncts are additional materials introduced to the mash or brew kettle to supplement the primary ingredients. Grains such as corn, rice, or wheat are often incorporated into the mash, relying on barley enzymes for starch breakdown. Syrups, already in a processed form, are typically added directly to the kettle.


Aflatoxin is a harmful and potentially carcinogenic compound produced by certain fungi, notably the Aspergillus mould, growing on grains. It's crucial to store barley and malt in dry settings to prevent mould development, as even minute aflatoxin amounts can be hazardous.

Alcohol by volume (ABV)

ABV indicates a beer's alcohol strength based on its volume. It measures the millilitres of alcohol present in every 100 grams of beer. Depending on the type, beer ABV can range from around 3% to about 10%.

Alcohol by weight (ABW)

ABW is another measure of beer's alcoholic concentration, representing the weight of its alcohol content. It's defined as the grams of alcohol in every 100 grams of beer. Typically, ABW is approximately 0.85 times the ABV, with beer ABWs varying from about 2.5% to near 8.5%.


Ale is a general term for beers that undergo fermentation at the top, distinguishing them from bottom-fermented lagers. Historically, "ale" indicated beers without hops or those with elevated alcohol levels.

Aleurone layer

The aleurone layer is the outermost cell layer surrounding barley grain, encasing the endosperm. When the embryo releases gibberellic acid, this layer responds by producing the enzyme a-amylase during malt development.


Amylose is a primary starch form present in barley endosperm and many other cereals. It's a linear chain of glucose molecules, which both a and b amylase enzymes can degrade during mashing.


a-amylase is a vital enzyme that plays a role in starch degradation during mashing. Its presence in raw barley is minimal, but its production surges during the malting phase. It targets the internal bonds of both amylose and amylopectin, producing a combination of simple sugars and larger dextrins.


b-amylase is another enzyme crucial for starch conversion during mashing. It's naturally abundant in barley even before the malting process. During mashing, it releases maltose units from the non-reducing ends of the starch chains.


Amylopectin is another dominant starch type in barley's endosperm and various grains. It's a branched glucose molecule structure. During mashing, both a and b amylase enzymes process it.


Anthocyanogens are certain phenolic compounds released from malt during the mashing process. They can modify the wort and beer's colour and, if not removed early on, might lead to haze formation due to their interaction with proteins during boiling and fermentation.

ATNC (Apparent Total N-nitroso Compounds)

ATNC is a parameter indicating nitrosamine levels in beer. These compounds can form during malt processing or due to bacterial fermentation. Proper malt kilning procedures have reduced current malt levels to under 0.5mg per Kg. Acid washing and maintaining yeast cleanliness can further reduce bacterial contributions.


Bacteria are microscopic entities with a simple cell design, usually smaller than 1µm. While most thrive in neutral pH environments, specific types, especially acetic and lactic acid bacteria, can flourish in beer, leading to unwanted flavour profiles.


Barley is the primary grain of choice for brewing. The major cultivated varieties include Hordeum vulgare and Hordeum distichon, each having several sub-types. Barley grains are nutrient-rich, packed with starch and enzymes. Two-row barleys, due to the selective growth of two grain rows on the stalk, are larger than four or six-row variants.

Barley Wine

Barley Wine is a distinguished strong ale with an ABV ranging between 6.5% and 11%. Characterized by its prominent alcohol, ester, and hop flavours, it offers a moderately bitter taste with a creamy mouthfeel, often appearing amber or golden in hue.


Beer is an alcoholic beverage crafted by fermenting sugars sourced mainly from malt and other cereals. With an ABV usually between 3 and 10%, it balances the malt's sweetness with the bitterness of hops. Additionally, fermentation imparts secondary flavours to the beer, such as fruity esters.

Beer engine

A beer engine is a manual pump facilitating the transfer of beer from the cellar to the bar for serving. Designed like a basic water pump, it incorporates one-way valves to prevent beer backflow. Beer gets pulled into a chamber and dispensed via a spout. This method, especially the elongated pull handle, is characteristic of cask ales.

Beer stone

Beer stone refers to mineral and organic compound deposits in fermenters, formed from settled calcium salts and proteins. Its removal can be challenging, and it might shield contaminating bacteria, thereby posing a cleanliness challenge.


Biotin is an essential vitamin for most brewing yeast growth. Adequate amounts are usually released from malt during the mashing process.


Bitter is a prominent beer style in the UK. It seamlessly blends bitterness, malt, and fruity undertones, typically made from pale and crystal malts with a substantial hop presence. Its alcohol content varies from 3.2 to 6.0%, with bitterness levels reaching up to 50 IBU. The beer's colour is commonly around 30, though it can soar to 100 EBC.


Bitterness in beer arises from the heat-induced transformation of a-acids from hops. During boiling, these humulones are isomerised to form iso a-acids that impart the bitter flavour. This bitterness is quantified in IBUs, with most beers falling between 20 and 50 IBU.

Bottom fermentation

Bottom fermentation pertains to beer fermentation using yeast that settles at the fermenter's bottom. It typically uses a lager yeast that ferments at cooler temperatures of 8 to 12°C. This allows the yeast to be harvested after racking the beer, although the yeast is often mixed with cold break trub, reducing its purity.


Brettanomyces is a genus of wild yeast not typically used in mainstream brewing. It introduces unique flavours, including the likes of butyric acid and capric esters. When exposed to oxygen, acetic acid can develop. These yeasts are notably present in certain Belgian sour beers and might have been abundant in older UK beer styles prior to yeast strain refinement.

Brewery conditioned beer

Brewery conditioned beer is a variant matured exclusively within the brewery premises and dispensed into casks or kegs without retaining its yeast. It usually undergoes filtration or pasteurisation for an extended shelf life of 6 to 10 weeks, in contrast to the 3 to 6 weeks of cask-conditioned counterparts.

Bright beer

Bright beer is one separated from its yeast sediment and relocated to a fresh vessel for dispensing. Ready for immediate consumption, it doesn't require a settling period. However, its freshness is fleeting, with optimal quality lasting under 24 hours due to the absence of yeast to counteract oxygen.

Brown Ale

Brown Ale stands out as a distinct British beer style. It's characterised by a robust malt backbone, moderate bitterness, and an underpinning of mild hops and fruity notes. Its alcohol content typically ranges between 4.5 and 5.0%, with a hue potentially reaching 70 EBC.

Burton Union system

Originating from Burton upon Trent, the Burton Union system is a classical fermentation approach. Here, fermentation takes place in expansive casks, with yeast being channeled from these casks into a collection trough via a long spout. This method is particularly compatible with Burton beers' flocculent yeast, reputedly producing unique flavour nuances. Its upkeep demands significant effort and resources, mainly due to intensive cleaning.


Calandria refers to the heat-exchanging surface in touch with wort. It can be situated within the brewing kettle or externally, warming the wort that's circulated over it.

Calcium oxalate

This is a non-soluble salt that precipitates from wort at various stages - from boiling to fermentation. It can crystallise into beer stone or stay suspended in beer, inducing a mild haze. Both a lack and an excess of calcium in wort can cause this precipitation.


Caramel originates from heated sugars, either alone or with nitrogen-based compounds. It naturally forms during the boiling of wort. However, man-made caramels can also be integrated into beer to enhance or adjust its colour and flavour.


Extracted from seaweed, carrageenan is a carbohydrate polymer. It's employed as finings, aiding in the rapid sedimentation of protein trub after boiling and yeast post-fermentation.


Casks are vessels designed for beer storage and dispensing. Historically made of wood, modern variants are crafted primarily from stainless steel or occasionally aluminium. Their distinct cylindrical shape with a central bulge ensures yeast settles away from the dispensing tap. When set for serving, a shive bung atop the cask is opened, admitting air or gas, while beer is drawn from a side tap.

Cask breather

A cask breather is a fundamental bidirectional device used to introduce carbon dioxide into cask-conditioned beer during its dispense. By preventing air entry, it minimises beer oxidation, thus extending its lifespan and preserving carbonation and flavour.

Cask conditioned beer

Cask conditioned beer is dispensed from a vessel housing live yeast. This beer undergoes a conditioning phase, marked by carbon dioxide generation and flavour maturation.

Cereal cooker

A cereal cooker is a vessel designed to process malt or adjunct grains either before or during mashing. Many adjuncts, due to their limited enzyme content, require the addition of barley malt or specific enzymes for starch conversion, a process executed within the cooker. The subsequent separation takes place in a separate lauter tun.


Cohumulone is a primary kind of a-acid sourced from hops. It isomerises to form iso a-acid, which is thought to impart a pronounced bitterness, though tannins might also play a role in this perception.

Cold break

Cold break refers to the trub that settles after the boiling process. When wort cools and fermentation begins, it manifests as flaky residues. Made up of lipids, proteins, and tannins, an effective cold break is vital for reducing beer haziness.


Collagen is the core protein found in isinglass finings.

Copper whirlpool

A vessel in which wort is boiled. The boiling process eliminates remaining microorganisms from the malt, stabilises flavours, and transforms a-acids into iso a-acids, imbuing the wort with bitterness. It's a pivotal stabilisation step in brewing.

Copper whirlpool is a vessel designed for boiling that integrates a side entry for circulating wort. This spiral movement centralizes the trub, allowing for the extraction of clear wort from the outer edges.

Crabtree effect

The Crabtree effect refers to a unique metabolic shift in yeast. Even in the presence of oxygen, pyruvic acid is converted into ethanol instead of evolving into carbon dioxide and water. This is contrary to many organisms that exhibit the Pasteur effect, where glucose is metabolized to carbon dioxide and water when oxygen is present.

Decoction mashing

Decoction mashing is an age-old European mashing method. Here, segments of the wort are boiled during mashing and then merged back into the primary mixture, causing a gradual temperature rise. It's a process designed for differential disintegration of grain elements and is especially beneficial for malt that is under-modified.


Dextrins are chains of glucose units that form during the mashing process. Generally made up of four to twenty glucose molecules, they don't undergo fermentation by brewing yeast. Instead, they linger in the beer, enhancing its body and texture.


Diacetyl is a distinct taste found in certain beers, resulting from the conversion of the acetolactate intermediary during fermentation. Its presence peaks during yeast proliferation but reduces during maturation as yeast reabsorbs it. Most breweries strive to keep diacetyl levels low, but some beer varieties, like British and Scotch ales, might tolerate higher concentrations.

Dimethyl sulphide (DMS)

Dimethyl sulphide (DMS) imparts a flavour reminiscent of certain vegetables, such as sweetcorn. It originates from malt's S-methyl methionine breaking down during boiling. With its high volatility, DMS can increase in wort if it remains hot after boiling. It's noticeable in beer at concentrations exceeding 90 mg per litre. It can also be a sign of bacterial contamination.

Dissolved oxygen (DO)

Dissolved oxygen (DO) measures the amount of oxygen dispersed in wort or beer. Oxygen's solubility in aqueous solutions is limited, but even minute quantities can oxidise compounds, potentially causing staleness in the beer or wort.

Dwarf hops

Dwarf hops are hops that grow to a shorter stature, typically around 3 metres, in contrast to traditional hops that can reach up to 6 metres. Their reduced height simplifies farming and harvesting processes. 'First Gold' pioneered this category, but subsequent variants also boast better resistance to diseases.

Emmer wheat

Emmer wheat, or Triticum dicocciodes, is an ancient grain variety. Employed in regions like Egypt and Northern Europe for baking and brewing, its hulls make it a brewing favourite as they aid in clarifying the wort after mashing.


Endosperm represents the part of cereal grains that stores starch. Comprising large cells packed with starch granules, the endosperm softens during malting due to cell wall digestion, and its starches are subsequently broken down during mashing to produce fermentable sugars.

Ethyl acetate

Ethyl acetate is a common ester produced during yeast metabolism. Arising from the fusion of acetate and ethanol, it introduces a solvent-like aroma.


Fermentation is yeast's main action, turning glucose into ethanol and carbon dioxide. This transformation also generates the energy yeast requires for growth and multiplication.


A fermenter is a vessel specifically crafted to house fermenting wort. Modern ones are typically made of stainless steel for longevity and hygiene, although earlier versions were made from materials like slate or copper. They often incorporate cooling systems to control temperature and mechanisms to release the carbon dioxide that forms.

Ferulic acid

Ferulic acid is a specific phenolic compound that gets released from malt. When transformed by wild yeast, it can generate spicy notes such as vinyl guaiacol. While often seen as an undesirable flavour in traditional beers, it's a defining trait in genuine wheat beers.


Filtration is a process that refines worts and beers by passing them through a specific membrane. This particular membrane, equipped with pores or multiple layers of fibres/particles, holds back solid substances, producing a transparent liquid. The retention efficiency is governed by the nature of the membrane. It primarily divides into absolute filtration and depth filtration, with cross-flow filtration presenting a reduced blockage potential.


Finings are substances added to either wort or beer to enhance the clumping and sedimentation of solids, predominantly trub and yeast. While auxiliary finings, extracted from carrageenan seaweed or silicates, are used mainly for clarifying trub from wort or beer, isinglass finings, obtained from fish collagen, facilitate yeast sedimentation.

First runnings

First runnings refer to the initial segment of wort directed from the copper to the fermenter. Due to potentially unclean wort pipelines, this segment can be prone to impurities. Some breweries adopt a method of briefly rerouting these early worts into the copper to cleanse the channels before directing to the fermenter.


Flocculation is the tendency of yeast cells to aggregate, allowing them to either ascend or descend rapidly. It's primarily determined genetically and usually initiates as fermentation approaches completion, characterized by dropping sugar concentrations and rising alcohol levels. Yeast strains differ in their flocculation strengths, affecting beer clarification during maturation and serving.


Foam is the effervescent layer that emerges atop beer when poured energetically. Comprising proteins, polysaccharides, and iso-humulones, it envelopes the gas bubbles that emanate from the beer. Certain agents, such as lipids, can undermine this layer, leading to the foam's dissolution. Beers rich in protein and bitterness generally showcase superior foam quality and longevity.


Fuggles is among the earliest identified hop varieties. Introduced in 1875 by Richard Fuggle, it continues to be a fundamental variety in the creation of iconic British beers.


b-glucan is a polymer present in cereal grain cell walls, entering the wort during malting and mashing phases. Acting essentially as a plant-based gum, it can intensify wort's consistency and impart beer with body. However, it may also extend filtration times. Certain mashing techniques target b-glucan breakdown using a temperature rest at 35°C, optimizing enzyme activity.


b-glucanase is an enzyme inherent to cereal grains, dedicated to breaking down b-glucan. Well-modified barley malt typically activates b-glucanases during malting, limiting b-glucan release in mashing. On the other hand, under-modified malt might require a 35°C temperature pause for b-glucanase to work on b-glucan.


Glycogen is a polysaccharide stored in yeast cells as fermentation winds down. It offers a vital energy source for cells when they re-enter the fermentation phase after a period of dormancy. Inadequate storage conditions can reduce glycogen reserves, possibly impacting fermentation performance.

Gram-negative bacteria

Gram-negative bacteria are those that adopt a pink coloration when subjected to Gram's bacterial identification technique. Their cellular structure doesn't retain the primary Gram stain (crystal violet) but reveals the counterstain, saffranin.

Gram-positive bacteria

Gram-positive bacteria are bacteria that manifest a violet hue when exposed to Gram's bacterial identification process. Their cellular composition holds onto the initial Gram stain, which is crystal violet.

Gravity of worts and beer

Gravity of worts and beer is a measure of the wort and beer's density. It's typically gauged by the buoyancy of a saccharometer that's calibrated for sugar solutions set against a water density of 1.000. Terms like 'og' denote the starting or original gravity of a fermentation, whereas 'pg', 'sg', or 'fg' refer to the subsequent gravities.


Grist is the collective term for dry goods added to the mash tun. While it's primarily made of barley malts, it can also encompass adjunct cereals such as wheat, rice, and maize.


Gushing is an abrupt ejection of gas and beer from a bottle. Contrary to the usual slow release of dissolved carbon dioxide in beer, certain conditions might cause a simultaneous release of gas and beer. Malted ingredients tainted with Fusarium moulds have been identified as potential gushing factors.


Gypsum is the calcium sulphate salt. It's often integrated into the grist to treat the liquor in the mash. The calcium can help precipitate phytate from the malt, while the sulphate can intensify bitterness.


Hallertau is a traditional hop from Eastern Europe, predominantly used in lager beers.


Haze describes the light cloudiness seen in worts and beers. Potential causes include the presence of protein-tannin particles, oxalic acid crystals, or microbial contamination. In beer, levels above 1.0 units are deemed concerning.


Heavy is a Scottish descriptor for a mid-strength ale, usually akin to a bitter in character.

High-gravity brewing

High-gravity brewing is a method of increasing the brew length by producing high gravity wort and beer, which can be watered down to yield a larger volume. This technique necessitates alcohol-tolerant yeasts and meticulous control to avoid overproduction of specific flavours.


Hops, or Humulus lupulus, are a vital brewing ingredient introduced to boiling wort to impart bitterness and hop aroma. The plant is a perennial climber, which can reach up to 6 meters in height, with clockwise twisting bines. Adapted into brewing in the last millennium, hops are integral to modern beers.

Hop back

Hop back is a vessel used to contain hops as wort drains from the copper. Extra hops can be added at this stage to infuse a distinct hop flavour.

Hop oils

Hop oils are the volatile organic components of hops, capturing most of the hop's aromatic qualities. This fraction has over 300 distinct compounds segregated into three main groups.

Hop resins

Hop resins are waxy substances extractable from hops using organic solvents. The soft resin fraction contains the a and b acids, which give beer its bitterness.

Hot break

Hot break is the trub material settled by boiling the wort. A well-formed hot break is crucial for clear beer production.


Humulone is the primary a acid derived from hops, which is transformed into bitter iso humulone during boiling.


Husk is the barley and malt grain's external layer. This layer remains integral during mashing, playing a crucial role during wort collection.

Ice beer

Ice beer is crafted through freeze concentration, where ice crystals are removed post-freezing, resulting in a stronger beer variant.

Immobilized yeast

Immobilized yeast refers to yeast affixed to support materials inside fermenter reactors. It plays a significant role in producing clearer beer.

India Pale Ale

India Pale Ale, historically developed as a British export beer for overseas colonies, was known for its robust bitterness to combat contamination during transport. Contemporary versions are lighter but maintain a distinct character.

Infusion mashing

Infusion mashing is a conventional mashing technique where the mash is maintained at a consistent temperature throughout the mashing duration. This temperature, typically between 60 and 70°C, is where amylase activity is at its peak. Infusion mashes are primarily used for UK beers made with well-modified malt, which has already undergone significant protein and b-glucan digestion during malting.

Irish moss

Irish moss is an extract from seaweed, added to boiling wort to promote protein precipitation at the boil's end. The traditionally used species are Chrodrus crispus and Gigartina stellata, though extracts from other seaweeds like Laminaria and Fucus species might be used nowadays.


Isinglass is a collagen extract sourced from the swim bladders of sturgeon and other fish. It's used as a fining aid to help yeast settle during beer conditioning and in cask-conditioned beer. The natural extract undergoes hydrolysis by acid, releasing highly positively charged collagen protein particles that strongly bind to negatively charged yeast cells, enhancing clarification.


A keg is a straight-sided container designed for beer dispense under pressure. Kegs feature a single entry valve: a central tube for beer exit and an outer collar for pressurised gas entry. Proper pressure application is crucial; excessive pressure can lead to gas absorption by the beer, causing fobbing during dispense. Brewery-conditioned beer in kegs is typically stabilized through filtration and/or pasteurisation.


Keiselguhr is an inert material used to enhance beer filtration by creating a finely porous cake on a filter membrane. As beer is progressively filtered, particles get trapped in the cake, allowing clear beer to pass through. Keiselguhr originates from diatom shells, but other filter aids may be composed of clay or silica hydrogel.

Lactic acid

Lactic acid is a prevalent acid produced by numerous yeasts and bacteria. It's a primary spoilage flavour that emerges from the growth of lactic acid bacteria in beer, noticeable by a yoghurt-like aroma and taste. Alongside lactic acid, these bacteria produce distinctive flavours, such as the butterscotch flavour diacetyl.


Lactobacillus is a leading group of lactic acid bacteria. Several species, including L. brevis, L. delbrueckii, and L. pastorianus, contaminate beer, generating lactic acid and other off-flavours. While these bacteria are typical contaminants in beer, they're also commonly utilised in food fermentations like yoghurt and sauerkraut.


Lager is a broad term referring to bottom-fermented beers, traditionally indicating beers matured for extended periods at cold temperatures. Contemporary lager beers are usually pale, with hints of dimethyl sulphide aroma and are hoppy with moderate bitterness. They are served from kegs through a fawcett after being filtered and brewery-conditioned, resulting in high carbonation.

Lambic ales

Lambic ales are beers fermented spontaneously with a diverse mix of moulds, wild yeast, and bacteria, yielding a sour, cider-like taste. A traditional Belgian beer, some versions are sweetened with fruits, especially raspberries and cherries. These beers evolve considerably with age, and blendings are often crafted to produce a balanced beer known as Gueuze.

Lauter tun

Lauter tun is a vessel used to rinse a mash and separate clear wort from the leftover grains. Differing from a mash tun, it's wider with a larger floor area, enabling a quicker runoff. Lauter tuns come equipped with stirring rakes for mash agitation and might be employed post-mash incubation in a cereal cooker with adjuncts. Utilising this system, more mashings can be executed daily, enhancing efficiency.


In the brewing context, liquor refers to the water used. Supply liquor is sourced either from local boreholes or direct water company provisions. Brewing liquor denotes the water used in the process, while process liquors are designated for other tasks such as washing or heating. The total volume of liquor used in brewing can be 4 to 10 times the beer volume produced. Reducing this volume is crucial for enhancing production efficiency and minimising environmental impact.

Low alcohol beer

Low alcohol beer is crafted either from a low-gravity wort that's partially fermented or from a higher-alcohol fermentation with the alcohol removed via evaporation. Typically brewed for specific markets, these beers lack the intricate character of standard beers and often have added malt and hop extracts for flavour enhancement.


Lupulone is a component of hop oil known for its spicy flavour.


Malt is a primary brewing ingredient offering sugars for yeast fermentation. Typically derived from barley, other grains like wheat, oats, and rye can also be malted. The malting process softens malted grains through enzyme action, producing a modified grain. This softening results from the digestion of cell wall materials, making the starch accessible for complete digestion during mashing.

Malt agar

Malt agar is a straightforward microbiological growth medium employed in laboratories for cultivating yeasts and moulds. It is formulated by blending malt extract with up to 2% agar.


Malting is the process of producing malt. It involves soaking grains in 2 or 3 water batches over 2-3 days to initiate germination. Germinating grains are spread on open floors, in long Saladin boxes, or in automated vessels with rotating arms that mix and control growth. Once the grains have matured sufficiently to generate adequate enzyme levels, they are dried in a kiln.


Maltose is a primary disaccharide sugar resulting from starch digestion during mashing. Comprising between 40 and 50% of the total sugar produced by this digestion, maltose consists of two glucose molecules bonded together, making it easily fermentable by yeast.


Maltotriose is a significant sugar produced from starch digestion during malting. Maltotriose is fermentable by most brewing yeast strains, but its fermentation efficiency depends on the yeast's health. Yeast that is old, stressed, or repitched multiple times might be less efficient at fermenting maltotriose, leading to incomplete fermentation and undesirably high final gravity.


Mashing is the initial significant brewing process stage where malt and liquor mix and incubate at predetermined temperatures. Starch is broken down into simple sugars, and numerous compounds are released from the malt, enriching the wort.

Mash filter

Mash filter is a large-scale method used for separating mash solids from the wort at mashing's end. Mash filters compress the mash in a large press, with the wort passing through a filter cloth while retaining the solids. This filtration method can be more efficient than standard mash tun separation, but the resulting wort might be cloudier.


Melanoidins are dark-colored compounds created by the combination of simple sugars and amino acids. This reaction speeds up during heating, primarily occurring during boiling. A variety of melanoidins emerge depending on wort components and boiling duration.


Mercaptans are distinct flavour compounds with a skunk-like aroma, resulting from the photolysis of iso a acids' side chain and the subsequent reaction with sulfur-containing thiol radicals.

Mild ale

Mild ale is a unique British beer with a subdued hop character, predominantly consumed in the north. Earlier versions were brewed with dark malts, providing a caramel and liquorice character and a robust body.


Milling is the process of crushing grains before mashing, ensuring the internal contents are exposed to the mash liquor, enhancing dissolution and enzyme digestion. Mills achieve this by crushing grain between rollers that operate in opposite directions.


Nitrogenation is the process of adding nitrogen gas to beer, resulting in a smoother palate upon dispense. Nitrogen has limited solubility in beer and necessitates high pressure for dissolution.


Nitrosamines are potentially carcinogenic compounds originating from wort's amides or amines, typically through bacterial activity. Present-day levels are low due to better brewing process control and reduced microbial contamination.


Oats are an auxiliary grain incorporated into some beers to impart a malty character and smooth mouthfeel.

Old ale

Old ale is a classic British beer known for its high alcohol content and rich, complex flavours. Typically dark and well-aged, it's often brewed as a seasonal winter drink.

Oxalic acid

Oxalic acid is an organic acid released into wort from barley and other grains. It can bind with calcium to produce precipitated calcium oxalate crystals.


Papain is a protease enzyme derived from the pineapple plant. It can be introduced to beer to decrease protein levels and guard against haze formation.


Paraflow is a heat exchanger used to heat or cool large volumes of beer. It's typically made of parallel stainless steel plates, with wort or beer running on one side and chilled water or steam on the other. The rate of heat exchange depends on the product's flow rate.


Pasteurisation is the process of heat treating beer to kill microorganisms, ensuring stability for brewery-processed beer. It's measured in pasteurising units (PU), which define the effect on microorganisms of holding the beer at 60°C for one minute.


Pediococcus is a coccus type of lactic acid bacteria capable of producing high levels of lactic acid, potentially spoiling wort and beer. They are non-spore forming, gram negative, and spherical, often distinguished by their diploid or tetrad cell arrangements.

Permanently soluble nitrogen

Permanently soluble nitrogen refers to the portion of protein and other nitrogen compounds that remain after precipitation during boiling. These proteins contribute to head formation and mouthfeel, making them a vital component of beer.


Phenols are cyclic organic compounds found in wort, many of which have distinct flavors. They can range from aromatic alcohol phenols that give beer a floral character to spicy flavors resulting from the decarboxylation of the phenol ferulic acid from malt.


Pilsner is a classic continental beer, known for its distinctive flowery aroma from using Saaz or Hallertau hops. Originating from the Czech town of Plzen, it's a golden and aromatic lager with a dry finish.

Plato – degrees of measurement

Plato – degrees of measurement relate wort strength to sugar concentration in a solution rather than its density. For context, a wort with a specific gravity of 1040 corresponds to 10° Plato.

Polymerase chain reaction (PCR)

Polymerase chain reaction (PCR) is a molecular biology technique. It allows the extraction and amplification of a single DNA piece from a sample, showcasing the presence of a particular gene or organism.


Porter is a unique type of British beer, traditionally concocted as a mixture of different beers. It's characterized by a balance of malt, roast, hop, bitterness, fruit, and spicy flavors.

Priming sugar

Priming sugar refers to the sugars added to beer post-fermentation to reignite yeast activity. It's crucial in some cask ales and bottle-conditioned beers where a secondary fermentation is necessary for added carbonation.

Proteolytic enzymes

Proteolytic enzymes are enzymes present in malt that break down proteins into polypeptides and amino acids. They play a significant role during malting by digesting much of the barley protein.


Quinones are phenolic compounds formed from the oxidation of polyphenols. They can act as oxidizing agents in wort, leading to stale flavors.


Rauchbier is a uniquely flavored German beer, known for its rich smoky taste. This flavor comes from malt dried in the smoke of moist beechwood fires.

Real ale

Real ale is another term for cask ale, which undergoes secondary conditioning after the primary fermentation. This conditioning typically occurs in a cask or bottle, which contains live yeast.


Saccharomyces is a yeast genus well-suited to fermenting strong sugar solutions, thus producing high alcohol levels. Saccharomyces cereisiae is the conventional brewing yeast, while other Saccharomyces yeasts are seen as contaminants, often termed "wild yeasts."

Saladin box

Saladin box is a container designed for the semi-automatic malting of cereals. Barley grains are placed in the box post-steeping, and air is sparged through the box's floor, with rakes slowly turning the grains.

Scotch ale

Scotch ale refers to national beers brewed in Scotland. They are maltier and less hoppy than other British beers, often having a sweeter taste due to a higher finishing gravity.


Shive is the wooden plug that seals the top of a cask. It has a central plug opened to the air before dispense, with wooden pegs called spiles inserted to manage air intake and gas release from the beer.

Silica hydrogel

Silica hydrogel, also known as lucilite, specifically absorbs proteins and polypeptides from wort. These particles, when added to beer during maturation or filtration, can act quickly to absorb polypeptides, aiding in clarification and stabilization.

Slack malt

Slack malt refers to malt that has absorbed water, becoming soft and stale.


Sparging is the process of washing grains post-mashing to extract residual sugars and maximize yield. It's ideal to use treated liquor at 77°C to reduce viscosity and halt enzyme activity.

Spent grains

Spent grains are the residual solids post-sparging. They consist of husks, barley embryo, roots and shoots, undissolved starch grains, and precipitated proteins and tannins. They're typically used as animal feed or for composting.


Starch is the primary storage polysaccharide in barley endosperm cells. It's produced from glucose molecules and consists of two molecular species: the linear polymer amylase and the branched polymer amylopectin. During mashing, starch grains dissolve, mostly from the larger grains.


Sterols are essential lipids for yeast membrane growth, contributing to membrane flexibility. They need oxygen for synthesis by the yeast cell. Yeasts, even if they multiply extensively during fermentation, need exposure to oxygen to produce sterols.


Stillage is a support structure for casks in the cellar. It ensures that yeast settles in the cask's belly, preventing it from being drawn into the beer during dispensation.


Stout is a distinctive British beer type, originally a stronger version of Porter. Characterized by a pronounced roast flavor, modern versions may be milder. Variations exist, including milk stout, oyster stout, and Imperial stout.

Strike temperature

Strike temperature refers to the brewing liquor's temperature added to the mash. Typically between 75 and 80°C, it's adjusted to achieve the desired final mash temperature and to help swell and gelatinize the starch grains.


Sucrose, or common table sugar, is a disaccharide made of glucose and fructose molecules. While only small amounts are found in malt, it can be added to wort as an adjunct or post-fermentation as a priming sugar.

Sunstruck beer

Sunstruck beer has undergone photolysis by light. This process releases specific compounds, resulting in the characteristic skunk smell, also detected in grass snakes.

Temperature programmed mashing

Temperature programmed mashing is a mashing method involving a stepped temperature increase. Typical steps include temperature stands at different levels to digest various components, finishing with a rise to 75°C to stop enzyme activity.


Testa is the innermost of the three protective layers surrounding the barley grain, forming part of the husk.

Top fermenting yeast

Top fermenting yeast are yeasts that rise to the wort's top during fermentation. They remain on the surface as a yeast head and can be skimmed for repitching in subsequent brews. Typically, ale yeasts ferment at the top, while lager yeasts ferment at the bottom.


Trehalose is a storage sugar present in yeast that provides energy reserves and protection against stress. High levels can develop towards fermentation's end, preparing the yeast for dormancy before its next exposure to sugars.


Trub refers to the precipitated proteins, tannins, and lipids formed in hot wort during boiling and in cold wort after being collected in the fermenter. Ideally, these are left behind when wort and beer are transferred to another vessel.


Unitank is a fermentation vessel that can also be utilized for beer conditioning, especially common in large-scale production.

Vacuum evaporation

Vacuum evaporation involves the removal of alcohols from beer by exposing it to low pressures, which enhances the evaporation of volatile compounds.


Vitality is a measure of yeast functionality, assessing the metabolic ability of yeast through tests like oxygen uptake rates or acid release.

Vicinyl diketones (VDK)

Vicinyl diketones (VDK) are molecules produced during fermentation as a result of nitrogen metabolism. Diacetyl, a VDK, emerges from acetolactate and imparts a strong butterscotch flavor.

Wallerstein media

Wallerstein media comprise agar mediums used for laboratory growth and yeast characterization. These mediums can distinguish yeast colonies based on their uptake of bromomethyl green dye.

Water treatments

Water treatments adjust the mash's acidity, typically through acid addition to neutralize bicarbonate salts and by introducing calcium salts to facilitate acid release from phytate.


A widget is a device placed inside a beer can that triggers a swift nitrogen gas release when the can is opened, resulting in a lasting, creamy head.

Wild yeasts

Wild yeasts are non-brewing yeasts. Even strains of Saccharomyces cerevisiae that aren't meant for brewing are considered "wild" if they alter the beer's flavor or affect the fermentation performance.


Wort is the sugar solution produced from the mashing process. Rich in various nutrients, it's an excellent growth medium for microorganisms.


Xylose is the foundational sugar of pentosan compounds in malt cell walls. Though pentosans aren't easily digested, when they are, they release xylose into the wort.


Yeast is a microscopic fungus. With over 700 recognized species, all yeasts have a single-celled structure with a rigid cell wall. The common brewing yeast is Saccharomyces cerevisiae.


Zentner is the standard measurement for packaged hops, where one zentner of whole leaf hops equates to 50Kg.


Zymonomas refers to a detrimental bacterial contaminant in beer. Zymonomas mobilis, the primary species found, produces distinctive off-flavors and can quickly spoil beer, especially when glucose and sucrose are present.