Brewing

BrewingFrom Wikipedia, the free encyclopedia"Brewer" redirects here. For other uses, seeBrewer (disambiguation).This article is about the brewing of beer. For making tea, seeTea brewing. For homebrewing, seeHomebrewing. For other uses, seeBrewing (disambiguation).

A 16th-century breweryBrewingis the production ofbeerbysteepingastarchsource (commonlycereal grains) in water andfermentingthe resulting sweet liquid with yeast. It may be done in abreweryby a commercial brewer, at home by ahomebrewer, or by a variety of traditional methods such as communally by theindigenous peoples in Brazilwhen makingcauim.[1]Brewing has taken place since around the 6th millennium BC, and archaeological evidence suggests that emerging civilizations includingancient Egypt[2]andMesopotamiabrewed beer.[3]Since the nineteenth century thebrewing industryhas been part of most western economies.The basic ingredients of beer are water and afermentablestarch source such asmalted barley. Most beer is fermented with abrewer's yeastand flavoured withhops.[4]Secondary starch sources (adjuncts), such as maize (corn), rice, or sugar, may also be used.[5]Less widely used starch sources includemillet,sorghumandcassava.[6]The amount of each starch source in a beer recipe is collectively called thegrain bill.Steps in the brewing process includemalting,milling,mashing,lautering,boiling,fermenting,conditioning,filtering, andpackaging. There are three main fermentation methods,warm,coolandspontaneous. Fermentation may take place in an open or closed fermenting vessel; a secondary fermentation may also occur in thecaskorbottle.Contents[hide] 1History 2Ingredients 3Brewing process 4Mashing 4.1Lautering 5Boiling 5.1Brew kettle or copper 5.2Whirlpool 5.3Hopback 5.4Wort cooling 6Fermenting 6.1Fermentation methods 6.1.1Warm fermentation 6.1.2Cool fermentation 6.1.3Spontaneous fermentation 7Conditioning 8Filtering 9Packaging 10Brewing methods 11By-products 12Brewing industry 13References 14External linksHistory[edit]Main article:History of beerBrewing has taken place since around the 6th millennium BC, and archaeological evidence suggests emerging civilizations includingancient EgyptandMesopotamiabrewed beer. Descriptions of various beer recipes can be found incuneiform(the oldest known writing) from ancientMesopotamia.[2][7][8]In Mesopotamia the brewer's craft was the only profession which derived social sanction and divine protection from female deities/goddesses, specifically:Ninkasi, who covered the production of beer,Siris, who was used in a metonymic way to refer to beer, andSiduri, who covered the enjoyment of beer.[3]Ingredients[edit]

Maltedbarleybefore roastingThe basic ingredients of beer are water; a starch source, such asmaltedbarley, able to be fermented (converted into alcohol); abrewer's yeastto produce the fermentation; and a flavouring, such ashops,[4]to offset the sweetness of the malt.[9]A mixture of starch sources may be used, with a secondary saccharide, such as maize (corn), rice, or sugar, often being termed anadjunct, especially when used as a lower-cost substitute for malted barley.[5]Less widely used starch sources includemillet,sorghum, andcassavaroot in Africa, potato in Brazil, andagavein Mexico, among others.[6]The amount of each starch source in a beer recipe is collectively called thegrain bill.WaterBeer is composed mostly of water. Regions have water with different mineral components; as a result, different regions were originally better suited to making certain types of beer, thus giving them a regional character.[10]For example,Dublinhashard waterwell suited to makingstout, such asGuinness; whilePilsenhas soft water well suited to makingpale lager, such asPilsner Urquell.[10]The waters ofBurtonin England containgypsum, which benefits makingpale aleto such a degree that brewers of pale ales will add gypsum to the local water in a process known asBurtonisation.[11]Starch sourceMain articles:MaltandMash ingredientsThe starch source in a beer provides the fermentable material and is a key determinant of the strength and flavour of the beer. The most common starch source used in beer is malted grain. Grain is malted by soaking it in water, allowing it to begingermination, and then drying the partially germinated grain in a kiln. Malting grain produces enzymes that will allow conversion from starches in the grain into fermentable sugars during the mash process.[12]Different roasting times and temperatures are used to produce different colours of malt from the same grain. Darker malts will produce darker beers.[13]Nearly all beer includes barley malt as the majority of the starch. This is because of its fibrous husk, which is important not only in the sparging stage of brewing (in which water is washed over themashedbarley grains to form thewort) but also as a rich source ofamylase, adigestiveenzymethat facilitates conversion of starch into sugars. Other malted and unmalted grains (including wheat, rice, oats, andrye, and, less frequently, maize (corn) and sorghum) may be used. In recent years, a few brewers have producedgluten-free beermade with sorghum with no barley malt for people that cannot digestgluten-containing grains like wheat, barley, and rye.[14]HopsMain article:Hops

Hop conein aHallertau, Germany, hop yardHops are the female flower clusters or seed cones of the hop vineHumulus lupulus,[15]which are used as a flavouring and preservative agent in nearly all beer made today.[16]Hops had been used for medicinal and food flavouring purposes since Roman times; by the 7th century inCarolingianmonasteries in what is now Germany, beer was being made with hops,[17]though it isn't until the thirteenth century that widespread cultivation of hops for use in beer is recorded.[18]Before the thirteenth century, beer was flavoured with plants such asyarrow,wild rosemary, andbog myrtle, and other ingredients such asjuniper berries,aniseedandginger, which would be combined into a mixture known asgruitand used as hops are now used; between the thirteenth and the sixteenth century, during which hops took over as the dominant flavouring, beer flavoured with gruit was known as ale, while beer flavoured with hops was known as beer.[19][20]Some beers today, such asFraochby the ScottishHeather Ales companyandCervoise Lancelotby the French Brasserie-Lancelot company, use plants other than hops for flavouring.[21][22]Hops contain several characteristics that brewers desire in beer: they contribute a bitterness that balances the sweetness of the malt; they provide floral, citrus, and herbal aromas and flavours; they have anantibioticeffect that favours the activity ofbrewer's yeastover less desirable microorganisms; and they aid in "head retention", the length of time that afoamy headwill last.[23]The preservative in hops comes from the lupulin glands which contain soft resins with alpha and beta acids.[24][25]Though much studied, the preservative nature of the soft resins is not yet fully understood, though it has been observed that unless stored at a cool temperature, the preservative nature will decrease.[26][27]Brewing is the sole major commercial use of hops.[28]YeastMain articles:Brewer's yeast,Saccharomyces cerevisiaeandSaccharomyces uvarumYeast is themicroorganismthat is responsible for fermentation in beer. Yeastmetabolisesthe sugars extracted from grains, which producesalcoholandcarbon dioxide, and thereby turnswortinto beer. In addition to fermenting the beer, yeast influences the character and flavour.[29]The dominant types of yeast used to make beer areSaccharomyces cerevisiae, known as ale yeast, andSaccharomyces pastorianus, known as lager yeast;Brettanomycesfermentslambics,[30]andTorulaspora delbrueckiiferments Bavarianweissbier.[31]Before the role of yeast in fermentation was understood, fermentation involved wild or airborne yeasts, and a few styles such aslambicsstill use this method today.Emil Christian Hansen, a Danish biochemist employed by theCarlsberg Laboratory, developed pure yeastcultureswhich were introduced into the Carlsberg brewery in 1883,[32]and pure yeast strains are now the main fermenting source used worldwide.[33]Clarifying agentMain article:FiningsSome brewers add one or moreclarifying agentsto beer, which typicallyprecipitate(collect as a solid) out of the beer along with protein solids and are found only in trace amounts in the finished product. This process makes the beer appearbrightand clean, rather than the cloudy appearance of ethnic and older styles of beer such aswheat beers.[34]Examples of clarifying agents includeisinglass, obtained fromswimbladdersof fish;Irish moss, a seaweed; kappacarrageenan, from the seaweedKappaphycus cottonii;Polyclar(artificial); andgelatin.[35]If a beer is marked "suitable for Vegans", it was generally clarified either with seaweed or with artificial agents,[36]although the "Fast Cask" method invented byMarston'sin 2009 may provide another method.[37]Brewing process[edit]

Diagram illustrating the process of brewing beerHot Water TankMash TunMaltHopsCopperHopbackAddYeasttoFermenterHeatexchangerBottlingCaskorKegThere are several steps in the brewing process, which may include malting, mashing, lautering,boiling,fermenting,conditioning,filtering, andpackaging.[38]Maltingis the process where barley grain is made ready for brewing.[39]Malting is broken down into three steps in order to help to release the starches in the barley.[40]First, during steeping, the grain is added to a vat with water and allowed to soak for approximately 40 hours.[41]Duringgermination, the grain is spread out on the floor of the germination room for around 5 days.[41]The final part of malting is kilning when the malt goes through a very high temperature drying in a kiln; with gradual temperature increase over several hours.[42]When kilning is complete, the grains are now termedmalt, and they will be milled or crushed to break apart the kernels and expose thecotyledon, which contains the majority of the carbohydrates and sugars; this makes it easier to extract the sugars during mashing.[43]Mashingconverts the starches released during the malting stage into sugars that can be fermented. The milled grain is mixed with hot water in a large vessel known as amash tun. In this vessel, the grain and water are mixed together to create a cereal mash. During the mash, naturally occurring enzymes present in the malt convert the starches (long chain carbohydrates) in the grain into smaller molecules or simple sugars (mono-, di-, and tri-saccharides). This "conversion" is calledsaccharification. The result of the mashing process is a sugar rich liquid or"wort", which is then strained through the bottom of the mash tun in a process known aslautering. Prior to lautering, the mash temperature may be raised to about 7578C (167172F) (known as a mashout) to deactivate enzymes. Additional water may be sprinkled on the grains to extract additional sugars (a process known assparging).[44]The wort is moved into a large tank known as a "copper" orkettlewhere it is boiled withhopsand sometimes other ingredients such as herbs or sugars. This stage is where many chemical and technical reactions take place, and where important decisions about the flavour, colour, and aroma of the beer are made.[45]The boiling process serves to terminate enzymatic processes,precipitateproteins,isomerizehopresins, and concentrate andsterilizethe wort. Hops add flavour,aromaandbitternessto the beer. At the end of the boil, the hopped wort settles to clarify in a vessel called a "whirlpool", where the more solid particles in the wort are separated out.[46]After the whirlpool, the wort is rapidly cooled via aheat exchangerto a temperature where yeast can be added. The heat exchanger consists of tubing inside a tub of cold water. It is very important to quickly cool the wort to a level where yeast can be added safely as yeast is unable to grow in high temperatures.[43]After the wort goes through the heat exchanger, the cooled wort goes into a fermentation tank. A type of yeast is selected and added, or "pitched", to the fermentation tank.[45]When the yeast is added to the wort, the fermenting process begins, where the sugars turn into alcohol,carbon dioxideand other components. When the fermentation is complete the brewer may rack the beer into a new tank, called a conditioning tank.[44]Conditioning of the beer is the process in which the beer ages, the flavour becomes smoother, and flavours that are unwanted dissipate.[46]After conditioning for a week to several months, the beer may befilteredandforce carbonatedfor bottling,[47]orfinedin thecask.[48]Mashing[edit]Main article:Mashing

A mash tun at theBass Museumin Burton-upon-TrentMashing is the process of combining a mix of milled grain (typicallymaltedbarleywithsupplementary grainssuch ascorn,sorghum,ryeor wheat), known as the "grain bill", and water, known as "liquor", and heating this mixture in a vessel called a "mash tun". Mashing is a form of steeping,[49]and defines the act of brewing, such as with making tea,sake, andsoy sauce.[50]Technically, wine,ciderandmeadare not brewed but rathervinified, as there is no steeping process involving solids.[51]Mashing allows theenzymesin the malt to break down thestarchin the grain into sugars, typicallymaltoseto create a malty liquid calledwort.[52]There are two main methods infusionmashing, in which the grains are heated in one vessel; anddecoctionmashing, in which a proportion of the grains are boiled and then returned to the mash, raising the temperature.[53]Mashing involves pauses at certain temperatures (notably 456273 C or 113144163F), and takes place in a "mash tun" an insulated brewing vessel with afalse bottom.[54][55][56]The end product of mashing is called a "mash".Mashing usually takes 1 to 2 hours, and during this time the various temperature rests activate different enzymes depending upon the type of malt being used, its modification level, and the intention of the brewer. The activity of these enzymes convert the starches of the grains todextrinsand then to fermentable sugars such asmaltose. A mash rest from 4955C (120131F) activates variousproteases, which break down proteins that might otherwise cause the beer to be hazy. This rest is generally used only with undermodified (i.e. undermalted) malts which are decreasingly popular in Germany and the Czech Republic, or non-malted grains such ascornand rice, which are widely used in North American beers. A mash rest at 60C (140F) activates -glucanase, which breaks down gummy -glucans in the mash, making the sugars flow out more freely later in the process. In the modern mashing process, commercial fungal based -glucanase may be added as a supplement. Finally, a mash rest temperature of 6571C (149160F) is used to convert the starches in the malt to sugar, which is then usable by the yeast later in the brewing process. Doing the latter rest at the lower end of the range favours-amylaseenzymes, producing more low-order sugars likemaltotriose,maltose, andglucosewhich are more fermentable by theyeast. This in turn creates a beer lower in body and higher in alcohol. A rest closer to the higher end of the range favours-amylaseenzymes, creating more higher-order sugars anddextrinswhich are less fermentable by the yeast, so a fuller-bodied beer with less alcohol is the result. Duration andpHvariances also affect the sugar composition of the resulting wort.[57]Lautering[edit]Main article:LauteringLautering is the separation of thewort(the liquid containing the sugar extracted during mashing) from the grains.[58]This is done either in a mash tun outfitted with a false bottom, in a lauter tun, or in a mash filter. Most separation processes have two stages: first wort run-off, during which the extract is separated in an undiluted state from the spent grains, andsparging, in which extract which remains with the grains is rinsed off with hot water. The lauter tun is a tank with holes in the bottom small enough to hold back the large bits of grist and hulls.[59]The bed of grist that settles on it is the actual filter. Some lauter tuns have provision for rotatingrakesor knives to cut into the bed of grist to maintain good flow. The knives can be turned so they push the grain, a feature used to drive the spent grain out of the vessel.[60]The mash filter is a plate-and-frame filter. The empty frames contain the mash, including the spent grains, and have a capacity of around one hectoliter. The plates contain a support structure for the filter cloth. The plates, frames, and filter cloths are arranged in a carrier frame like so: frame, cloth, plate, cloth, with plates at each end of the structure. Newer mash filters have bladders that can press the liquid out of the grains between spargings. The grain does not act like a filtration medium in a mash filter.[61]Boiling[edit]After mashing, the beerwortis boiled withhops(and other flavourings if used) in a large tank known as a "copper" or brew kettle though historically the mash vessel was used and is still in some small breweries.[62]The boiling process is where chemical and technical reactions take place,[45]includingsterilizationof the wort to remove unwanted bacteria, releasing of hop flavours, bitterness and aroma compounds throughisomerization, stopping of enzymatic processes,precipitationof proteins, and concentration of the wort.[63][64]Finally, the vapours produced during the boil volatiliseoff-flavours, includingdimethyl sulfideprecursors.[64]The boil is conducted so that it is even and intense a continuous "rolling boil".[64]The boil on average lasts between 45 and 90 minutes, depending on its intensity, the hop addition schedule, and volume of water the brewer expects to evaporate.[65]At the end of the boil, solid particles in the hopped wort are separated out, usually in a vessel called a "whirlpool".[46]Brew kettle or copper[edit]

Brew kettles atCoors Brewing CompanyCopper is the traditional material for the boiling vessel, because copper transfers heat quickly and evenly, and because the bubbles produced during boiling, and which would act as an insulator against the heat, do not cling to the surface of copper, so the wort is heated in a consistent manner.[66]The simplest boil kettles are direct-fired, with a burner underneath. These can produce a vigorous and favourable boil, but are also apt to scorch the wort where the flame touches the kettle, causing caramelisation and making cleanup difficult. Most breweries use a steam-fired kettle, which uses steam jackets in the kettle to boil the wort.[64]Breweries usually have a boiling unit either inside or outside of the kettle, usually a tall, thin cylinder with vertical tubes, called a calandria, through which wort is pumped.[67]Whirlpool[edit]At the end of the boil, solid particles in the hopped wort are separated out, usually in a vessel called a "whirlpool" or "settling tank".[46][68]The whirlpool was devised by theMolson Breweryin 1960 to utilise the so-calledtea leaf paradoxto force the denser solids known as "trub" (coagulated proteins, vegetable matter from hops) into a cone in the centre of the whirlpool tank.[69]Whirlpool systems vary: smaller breweries tend to use the brew kettle, larger breweries use a separate tank,[68]and design will differ, with tank floors either flat, sloped, conical or with a cup in the centre.[70]The principle in all is that by swirling the wort thecentripetal forcewill push the trub into a cone at the centre of the bottom of the tank, where it can be easily removed.[68]Hopback[edit]A hopback is a traditional additional chamber that acts as a sieve or filter by using wholehopsto clear debris (or "trub") from the green (or unfermented)wort, as the whirlpool does, and also to increase hop aroma in the finished beer.[71][72]It is a sealed chamber between the brewing kettle and counter-flow wort chiller. Hops are added to the chamber, the hot wort from the kettle is run through it, and then immediately cooled in the wort chiller before entering the fermentation chamber. Because it is a sealed chamber it facilitates maximum retention of volatile hop aroma compounds that would normally be driven off when the hops contact the hot wort.[73]While a hopback has the same filtering effect as a whirlpool, it operates differently: a whirlpool uses centrifugal forces, a hopback uses a layer of whole hops to act as a filter bed. Furthermore, while a whirlpool is useful only for the removal of pelleted hops (as flowers do not tend to separate as easily), in general hopbacks are used only for the removal of whole flower hops (as the particles left by pellets tend to make it through the hopback).[74]The hopback has mainly been substituted in modern breweries by the whirlpool.[75]Wort cooling[edit]After the whirlpool, the wort must be brought down to fermentation temperatures (2026Celsius)[54]before yeast is added. In modern breweries this is achieved through a plateheat exchanger. A plate heat exchanger has many ridged plates, which form two separate paths. The wort is pumped into the heat exchanger, and goes through every other gap between the plates. The cooling medium, usually water, goes through the other gaps. The ridges in the plates ensure turbulent flow. A good heat exchanger can drop 95C wort to 20C while warming the cooling medium from about 10C to 80C. The last few plates often use a cooling medium which can be cooled to below thefreezing point, which allows a finer control over the wort-out temperature, and also enables cooling to around 10C. After cooling, oxygen is often dissolved into the wort to revitalize the yeast and aid its reproduction.While boiling, it is useful to recover some of the energy used to boil the wort. On its way out of the brewery, the steam created during the boil is passed over a coil through which unheated water flows. By adjusting the rate of flow, the output temperature of the water can be controlled. This is also often done using a plate heat exchanger. The water is then stored for later use in the next mash, in equipment cleaning, or wherever necessary.[76]Another common method of energy recovery takes place during the wort cooling. When cold water is used to cool the wort in a heat exchanger, the water is significantly warmed. In an efficient brewery, cold water is passed through the heat exchanger at a rate set to maximize the water's temperature upon exiting. This now-hot water is then stored in a hot water tank.[76]Fermenting[edit]

Modern closed fermentation vesselsFermentationtakes place in fermentation vessels which come in various forms, from enormous cylindroconical vessels, through open stone vessels, to wooden vats.[77][78][79]After the wort is cooled andaerated usually withsterileair yeast is added to it, and it begins to ferment. It is during this stage that sugars won from themaltare converted into alcohol andcarbon dioxide, and the product can be called beer for the first time.Most breweries today use cylindroconical vessels, or CCVs, which have a conical bottom and a cylindrical top. The cone'sapertureis typically around 60, an angle that will allow the yeast to flow towards the cone's apex, but is not so steep as to take up too much vertical space. CCVs can handle both fermenting and conditioning in the same tank. At the end of fermentation, the yeast and other solids which have fallen to the cone's apex can be simply flushed out of a port at the apex. Open fermentation vessels are also used, often for show in brewpubs, and in Europe in wheat beer fermentation. These vessels have no tops, which makes harvesting top-fermenting yeasts very easy. The open tops of the vessels make the risk of infection greater, but with proper cleaning procedures and careful protocol about who enters fermentation chambers, the risk can be well controlled. Fermentation tanks are typically made of stainless steel. If they are simple cylindrical tanks with beveled ends, they are arranged vertically, as opposed to conditioning tanks which are usually laid out horizontally. Only a very few breweries still use wooden vats for fermentation as wood is difficult to keep clean and infection-free and must be repitched more or less yearly.[77][78][79]Fermentation methods[edit]See also:Beer style

Open vessel showing fermentation taking placeThere are three main fermentation methods,warm,coolandwild or spontaneous. Fermentation may take place in open or closed vessels. There may be a secondary fermentation which can take place in the brewery, in thecaskor in thebottle.Brewing yeasts are traditionally classed as "top-cropping" (or "top-fermenting") and "bottom-cropping" (or "bottom-fermenting").[80]Yeast were termed top or bottom cropping, because in traditional brewing yeast was collected from the top or bottom of the fermenting wort to be reused for the next brew.[81]This terminology is somewhat inappropriate in the modern era; after the widespread application of brewing mycology it was discovered that the two separate collecting methods involved two different yeast species that favoured different temperature regimes, namelySaccharomyces cerevisiaein top-cropping at warmer temperatures andSaccharomyces pastorianusin bottom-cropping at cooler temperatures.[82]As brewing methods changed in the 20th century, cylindro-conical fermenting vessels became the norm and the collection of yeast for bothSaccharomycesspecies is done from the bottom of the fermenter, thus the method of collection no longer implies a species association. There are a few remaining breweries who collect yeast in the top-cropping method, such as Samuel Smiths brewery in Yorkshire, Marstons in Staffordshire and several German hefeweizen producers.[81]For both types, yeast is fully distributed through the beer while it is fermenting, and both equallyflocculate(clump together and precipitate to the bottom of the vessel) when fermentation is finished. By no means do all top-cropping yeasts demonstrate this behaviour, but it features strongly in many English yeasts that may also exhibit chain forming (the failure of budded cells to break from the mother cell), which is in the technical sense different from true flocculation. The most common top-cropping brewer's yeast,Saccharomyces cerevisiae, is the same species as the common baking yeast. However, baking and brewing yeasts typically belong to different strains, cultivated to favour different characteristics: baking yeast strains are more aggressive, in order to carbonatedoughin the shortest amount of time; brewing yeast strains act slower, but tend to tolerate higher alcohol concentrations (normally 12-15% abv is the maximum, though under special treatment some ethanol-tolerant strains can be coaxed up to around 20%).[83]Modern quantitative genomics has revealed the complexity ofSaccharomycesspecies to the extent that yeasts involved in beer and wine production commonly involve hybrids of so-called pure species. As such, the yeasts involved in what has been typically called top-cropping or top-fermenting ale may be bothSaccharomyces cerevisiaeand complex hybrids ofSaccharomyces cerevisiaeandSaccharomyces kudriavzevii. Three notable ales,Chimay,OrvalandWestmalle, are fermented with these hybrid strains, which are identical to wine yeasts from Switzerland.[84]Warm fermentation[edit]In general, yeasts such asSaccharomyces cerevisiaeare fermented at warm temperatures between 15 and 20C (59 and 68F), occasionally as high as 24C (75F),[85]while the yeast used byBrasserie Dupontforsaisonferments even higher at 29 to 35C (84 to 95F).[86]They generally form a foam on the surface of the fermenting beer, as during the fermentation process itshydrophobicsurface causes the flocs to adhere to CO2and rise; because of this, they are often referred to as "top-cropping" or "top-fermenting"[87] though this distinction is less clear in modern brewing with the use of cylindro-conical tanks.[88]Generally, warm-fermented beers are ready to drink within three weeks after the beginning of fermentation, although some brewers will condition them for several months.Cool fermentation[edit]This sectionneeds additional citations forverification.Please helpimprove this articlebyadding citations to reliable sources. Unsourced material may be challenged and removed.(April 2013)

Main article:LagerLager is beer that has been cool fermented at around 10C (50F) (compared to typical warm fermentation temperatures of 18C (64F)), then stored for around 30 days at temperatures close tofreezingpoint;[citation needed]during this storagesulphurcomponents developed during fermentation dissipate.[citation needed]Though it is the cool fermentation that defines lager, the main technical difference with lager yeast,Saccharomyces pastorianus, is its divergent genome and its ability to metabolize both melibiose, a disaccharide of galactose and glucose andraffinose(atrisaccharidecomposed of the sugarsgalactose,fructose, andglucose).[citation needed][clarification needed]Ale yeasts,Saccharomyces cerevisiae, can only partially metabolize raffinose and cannot metabolize melibiose at all. Nonetheless, these sugars are not present in typical beer wort made from malted barley and their metabolism or lack of it will not affect the subsequent beer organoleptic qualities in any way.[89]Brewers inBavariahad for centuries been selecting cold-fermenting yeasts by storing ("lagern") their beers in cold alpine caves. The process of natural selection meant that the wild yeasts that were most cold tolerant would be the ones that would remain actively fermenting in the beer that was stored in the caves. A sample of these Bavarian yeasts was sent from the Spaten brewery in Munich to the Carlsberg brewery in Copenhagen in 1845 who began brewing with it. In 1883 Emile Hansen completed a study on pure yeast culture isolation and the pure strain obtained from Spaten went into industrial production in 1884 as Carlsberg yeast No 1. Another specialized pure yeast production plant was soon installed at the Heineken Brewery in Rotterdam the following year and together they began supply of pure cultured yeast to brewers across Europe.[90][91]This yeast strain was originally classified asSaccharomyces carlsbergensisa now defunct species name which has been superseded by the currently accepted taxonomic classificationSaccharomyces pastorianus.Today, lagers represent the vast majority of beers produced. Examples includeBudweiser Budvar,Birra Moretti,Stella Artois,Red Stripe, andSingha. Some lagers are marketed asPilsner, which originated inPilsen, Czech Republic(Plze inCzech).[clarification needed][citation needed]Lager yeast normally ferments at a temperature of approximately 5C (41F). Lager yeast can be fermented at a higher temperature normally used for top-fermenting yeast, and this application is often used in a beer style known asCalifornia Commonor colloquially as "steam beer".Spontaneous fermentation[edit]"Wild yeast" redirects here. For the role of wild yeast in winemaking, seeYeast in winemaking.Lambicbeers are historically brewed inBrusselsand the nearbyPajottenlandregion of Belgium without any yeast inoculation.[92][93]They are fermented in oak barrels with the resident microbiota present in the wood and can take up to 2 years to come into condition for sale.[94]However, with the advent of yeast banks and theNational Collection of Yeast Cultures, brewing these beers albeit not through spontaneous fermentation is possible anywhere. Specific bacteria cultures are also available to reproduce certain styles.[citation needed]Brettanomycesis a genus of yeast important in brewinglambic, a beer produced not by the deliberate addition of brewer's yeasts, but by spontaneous fermentation with wild yeasts and bacteria.[95]Conditioning[edit]

Conditioning tanks atAnchor Brewing CompanyAfter an initial or primary fermentation, beer is conditioned, matured or aged,[96]in one of several ways,[97]which can take from 2 to 4 weeks, several months, or several years, depending on the brewer's intention for the beer. The beer is usually transferred into a second container, so that it is no longer exposed to the dead yeast and other debris (also known as "trub") that have settled to the bottom of the primary fermenter. This prevents the formation of unwanted flavours and harmful compounds such asacetylaldehydes.[98]KruseningKrusening is a conditioning method in which fermentingwortis added to the finished beer.[99]The active yeast will restart fermentation in the finished beer, and so introduce fresh carbon dioxide; the conditioning tank will be then sealed so that the carbon dioxide is dissolved into the beer producing a lively "condition" or level of carbonation.[99]The krusening method may also be used to condition bottled beer.[99]LageringLagersare stored at near freezing temperatures for 16 months while still on the yeast.[100]The process of storing, or conditioning, or maturing, or aging a beer at a low temperate for a long period is called "lagering", and while it is associated with lagers, the process may also be done with ales, with the same results that of cleaning up various chemicals, acids and compounds.[101]Secondary fermentationDuring secondary fermentation, most of the remaining yeast will settle to the bottom of the second fermenter, yielding a less hazy product.[102]Bottle fermentationSome beers undergo a fermentation in the bottle, giving natural carbonation.[103]This may be a second or third fermentation. They are bottled with a viable yeast population in suspension. If there is no residual fermentable sugar left, sugar orwortor both may be added in a process known as priming. The resulting fermentation generatesCO2that is trapped in the bottle, remaining in solution and providing natural carbonation. Bottle-conditioned beers may be either filled unfiltered direct from the fermentation or conditioning tank, or filtered and then reseeded with yeast.[104]Cask conditioningMain article:Cask aleCask ale or cask-conditioned beer isunfilteredandunpasteurisedbeer that is conditioned (including secondary fermentation) and served from a cask, either pumped up from a cellar via abeer engine(hand pump), or from a tap by gravity.[105]Sometimes acask breatheris used to keep the beer fresh by allowing carbon dioxide to replace oxygen as the beer is drawn off the cask.[106]The term "real ale" as used by theCampaign for Real Ale(CAMRA) refers to beer "served without the use ofextraneous carbon dioxide", which would disallow the use of a cask breather.[107][108]Filtering[edit]This sectiondoes notciteanyreferences or sources.Please help improve this section byadding citations to reliable sources. Unsourced material may be challenged andremoved.(April 2012)

Main article:Filtered beer

A mixture ofdiatomaceous earthandyeastafter filtering.Filtering the beer stabilizes the flavour, and gives beer its polished shine and brilliance. Not all beer is filtered. When tax determination is required by local laws, it is typically done at this stage in a calibrated tank.Filters come in many types. Many are in the form of sheets or "candles". Others use a fine powder such asdiatomaceous earth, also called kieselguhr. The powder is added to the beer and recirculated past screens to form a filtration bed.Filters range from rough filters that remove much of the yeast and any solids (e.g., hops, grain particles) left in the beer, to filters tight enough to strain colour and body from the beer. Filtration ratings are divided into rough, fine, and sterile. Rough filtration leaves some cloudiness in the beer, but it is noticeably clearer than unfiltered beer. Fine filtration removes almost all cloudiness. Sterile filtration removes almost all microorganisms.Sheet (pad) filtersThese filters use sheets that allow only particles smaller than a given size to pass through. The sheets are placed into a filtering frame, sanitized (with boiling water, for example) and then used to filter the beer. The sheets can be flushed if the filter becomes blocked. The sheets are usually disposable and are replaced between filtration sessions. Often the sheets contain powdered filtration media to aid in filtration.Pre-made filters have two sides. One with loose holes, and the other with tight holes. Flow goes from the side with loose holes to the side with the tight holes, with the intent that large particles get stuck in the large holes while leaving enough room around the particles and filter medium for smaller particles to go through and get stuck in tighter holes.Sheets are sold in nominal ratings, and typically 90% of particles larger than the nominal rating are caught by the sheet.Kieselguhr filtersFilters that use a powder medium are considerably more complicated to operate, but can filter much more beer before regeneration. Common media includediatomaceous earthandperlite.Packaging[edit]See also:Beer bottle,Beverage can,Widget (beer),Draught beerandCask alePackaging is putting the beer into the containers in which it will leave the brewery. Typically, this means putting the beer into bottles, aluminium cans andkegs/casks, but it may include putting the beer into bulk tanks for high-volume customers.Brewing methods[edit]Main article:Brewing methodsThere are several additional brewing methods, such as barrel aging, double dropping, and Yorkshire Square.By-products[edit]Brewing by-products are "spent grain" and the sediment (or "dregs") from the filtration process which may be dried and resold as "brewers dried yeast" for poultry feed,[109]or made into yeast extract.Yeast extractYeast extractis used in brands such asVegemiteandMarmite.[110]The process of turning the yeast sediment into edible yeast extract was discovered by a German scientistJustus Liebig.[111]Spent grain

Spent grainBrewer's spent grain (also called spent grain, brewer's grain or draff) consists of the residue of malt and grain which remains in the mash-kettle after the mashing and lautering process.[112]It consists primarily of grain husks,pericarp, and fragments ofendosperm.[113]As it mainly consists ofcarbohydratesandproteins,[113]and is readily consumed by animals,[114]spent grain is used inanimal feed.[114]Spent grains can also be used asfertilizer, whole grains in bread,[115]as well as in the production ofbiogas. Spent grain is also an ideal medium for growingmushrooms, such asshiitake, and already some breweries are either growing their own mushrooms or supplying spent grain to mushroom farms.[116]Spent grains can be used in the production of red bricks, to improve the open porosity and reduce thermal conductivity of the ceramic mass.[117]Brewing industry[edit]The brewing industry is a global business, consisting of several dominantmultinational companiesand many thousands of smaller producers known asmicrobreweriesor regional breweries depending on size and region.[118][119]More than 133billion liters (3.51010U.S. gallons; 2.91010imperial gallons) are sold per yearproducing total global revenues of $294.5 billion (147.7 billion) as of 2006.[120]SABMillerbecame the largest brewing company in the world when it acquired Royal Grolsch, brewer of Dutch premium beer brandGrolsch.[121]InBevwas the second-largest beer-producing company in the world andAnheuser-Buschheld the third spot, but after the acquisition of Anheuser-Busch by InBev, the newAnheuser-Busch InBevcompany is currently the largest brewer in the world.[122]Brewing at homeis subject to regulation and prohibition in many countries. Restrictions on homebrewing were lifted in the UK in 1963,[123]Australia followed suit in 1972,[124]and the USA in 1978, though individual states were allowed to pass their own laws limiting production.[125]

Mashing

Inbrewinganddistilling,mashingis the process of combining a mix of milledgrain(typicallymaltedbarleywithsupplementary grainssuch ascorn,sorghum,ryeorwheat), known as the "grain bill", and water, known as "liquor", and heating this mixture. Mashing allows theenzymesin the malt to break down thestarchin the grain intosugars, typicallymaltoseto create a malty liquid calledwort.[1]There are two main methodsinfusionmashing, in which the grains are heated in one vessel; anddecoctionmashing, in which a proportion of the grains are boiled and then returned to the mash, raising the temperature.[2]Mashing involves pauses at certain temperatures (notably 456273 C or 113144163F), and takes place in a "mash tun"an insulated brewing vessel with a false bottom.[3][4][5]The end product of mashing is called a "mash".[citation needed]Infusion mashing[edit]Most breweries useinfusionmashing, in which the mash is heated directly to go from rest temperature to rest temperature. Some infusion mashes achieve temperature changes by adding hot water, and there are also breweries that do single-step infusion, performing only one rest beforelautering.Decoction mashing[edit]Decoctionmashing is where a proportion of the grains are boiled and then returned to the mash, raising the temperature. The boiling extracts more starch from the grain by breaking down the cell walls of the grain. It can be classified into one-, two-, and three-step decoctions, depending on how many times part of the mash is drawn off to be boiled.[6]It is a traditional method, and is common in German and Central European breweries.[7][8]It was used out of necessity before the invention ofthermometersallowed simpler step mashing. But the practice continues for many traditionalbeersbecause of the unique malty flavor it lends to the beer; boiling part of the grain results inMaillard reactions, which createmelanoidinsthat lead to rich, malty flavours.[9]Ingredient selection[edit]See also:Mash ingredientsEach particular ingredient has its own flavor that contributes to the final character of the beverage. In addition, different ingredients carry other characteristics, not directly relating to the flavor, which may dictate some of the choices made in brewing: nitrogen content, diastatic power, color, modification, and conversion.Nitrogen content[edit]Thenitrogencontent of a grain refers to the mass fraction of the grain that is made up ofprotein, and is usually expressed as apercentage; this fraction is further refined by distinguishing what fraction of the protein iswater-soluble, also usually expressed as a percentage; 40% is typical for most beermaking grains. Generally, brewers favor lower-nitrogen grains, while distillers favor high-nitrogen grains.In most beermaking, an average nitrogen content in the grains of at most 10% is sought; higher protein content, especially the presence of high-mass proteins, causes "chill haze", a cloudy visual quality to the beer. However, this is mostly a cosmetic desire dating from the mass production ofglasswarefor presenting serving beverages; traditional styles such assahti,saison, andbire de garde, as well as severalBelgian styles, make no special effort to create a clear product. The quantity of high-mass proteins can be reduced during the mash by making use of aproteaserest.In Britain, preferred brewers' grains are often obtained from winter harvests and grown in low-nitrogen soil; in central Europe, no special changes are made for the grain-growing conditions and multi-step decoction mashing is favored instead.Distillers, by contrast, are not as constrained by the amount of protein in their mash as the non-volatile nature of proteins means that none will be included in the final distilled product. Therefore, distillers seek out higher-nitrogen grains in order to ensure a more efficiently-made product; higher-protein grains generally have more diastatic power.Diastatic power[edit]Diastatic power (DP), also called the "diastatic activity" or "enzymatic power", is a property ofmalts, grains that have begun togerminate, and is used to measure the malt's ability to break down starches into simpler fermentable sugars during the mashing process. The act of germination produces a number ofenzymessuch asamylasethat can convert thestarchnaturally present in barley and other grains into sugar. The mashing process activates these enzymes by soaking the grain in water at a controlled temperature.In general, the hotter a grain is kilned, the less its diastatic activity; as a consequence, only lightly colored grains can be used as base malts, withMunich maltbeing the darkest base malt generally available.Diastatic activity can also be provided by diastatic malt extract or by inclusion of separately-prepared brewing enzymes.Diastatic power for a grain is measured in degreesLintner(Lintneror L, although the latter can conflict with the symbol L for Lovibond color); or in Europe byWindisch-Kolbach units(WK). The two measures are related by

.A malt with enough power to self-convert has a diastatic power near 35 Lintner (94 WK). Until recently, the most active, so-called "hottest", malts currently available were American six-row pale barley malts, which have a diastatic power of up to 160 Lintner (544 WK). Wheat malts have begun to appear on the market with diastatic power of up to 200 Lintner. Although with the huskless wheat being somewhat difficult to work with, this is usually used in conjunction with barley, or as an addition to add high diastatic power to a mash.Color[edit]In brewing, the color of a grain or product is evaluated by theStandard Reference Method(SRM),Lovibond(L),American Society of Brewing Chemists(ASBC) orEuropean Brewery Convention(EBC) standards. While SRM and ASBC originate in North America and EBC in Europe, all three systems can be found in use throughout the world; degrees Lovibond has fallen out of industry use but has remained in use inhomebrewingcircles as the easiest to implement without aspectrophotometer. The darkness of grains range from as light as less than 2 SRM/4 EBC for Pilsener malt to as dark as 700 SRM/1600 EBC for black malt and roasted barley.Modification[edit]The quality of starches in a grain is variable with the strain of grain used and its growing conditions. "Modification" refers specifically to the extent to which starch molecules in the grain consist of simple chains of starch molecules versus branched chains; a fully modified grain contains only simple-chain starch molecules. A grain that is not fully modified requires mashing in multiple steps rather than at simply one temperature as the starches must be de-branched before amylase can work on them. One indicator of the degree of modification of a grain is that grain's Nitrogen ratio; that is, the amount of soluble Nitrogen (or protein) in a grain vs. the total amount of Nitrogen(or protein). This number is also referred to as the "Kolbach Index" and a malt with a Kolbach index between 36% and 42% is considered a malt that is highly modified and suitable for single infusion mashing. Maltsters use the length of the acrospire vs. the length of the grain to determine when the appropriate degree of modification has been reached before drying or kilning.Conversion[edit]Conversion is the extent to which starches in the grain have been enzymatically broken down into sugars. A caramel or crystal malt is fully converted before it goes into the mash; most malted grains have little conversion; unmalted grains, meanwhile, have little or no conversion. Unconverted starch becomes sugar during the last steps of mashing, through the action of alpha and beta amylases.Grain milling[edit]The grain used for making beer must first bemilled. Milling increases the surface area of the grain, making the starch more accessible, and separates the seed from thehusk. Care must be taken when milling to ensure that the starch reserves are sufficiently milled without damaging the husk and providing coarse enough grits that a good filter bed can be formed during lautering.Grains are typically dry-milled. Dry mills come in four varieties: two-, four-, five-, and six-roller mills. Hammer mills, which produce a very fine mash, are often used when mash filters are going to be employed in the lautering process because the grain does not have to form its own filterbed. In modern plants, the grain is often conditioned with water before it is milled to make the husk more pliable, thus reducing breakage and improving lauter speed.Two-roller millsTwo-roller mills are the simplest variety, in which the grain is crushed between two rollers before it continues on to the mash tun. The spacing between these two rollers can be adjusted by the operator. Thinner spacing usually leads to better extraction, but breaks more husk and leads to a longer lauter.Four-roller millsFour-roller mills have two sets of rollers. The grain first goes through rollers with a rather wide gap, which separates the seed from the husk without much damage to the husk, but leaves large grits. Flour is sieved out of the cracked grain, and then the coarse grist and husks are sent through the second set of rollers, which further crush the grist without damaging the crusts. There are three-roller mills, in which one of the rollers is used twice, but they are not recognized by the German brewing industry.Five- and Six-roller millsSix-roller mills have three sets of rollers. The first roller crushes the whole kernel, and its output is divided three ways: Flour immediately is sent out the mill, grits without a husk proceed to the last roller, and husk, possibly still containing parts of the seed, go to the second set of rollers. From the second roller flour is directly output, as are husks and any possible seed still in them, and the husk-free grits are channeled into the last roller. Five-roller mills are six-roller mills in which one of the rollers performs double-duty.Mashing-in[edit]Mixing of the strike water, water used for mashing in, and milled grist must be done in a such a way as to minimize clumping and oxygen uptake. This was traditionally done by first adding water to the mash vessel, and then introducing the grist from the top of the vessel in a thin stream. This has led to a lot of oxygen absorption, and loss of flour dust to the surrounding air. A premasher, which mixes the grist with mash-in temperature water while it is still in the delivery tube, reduces oxygen uptake and prevents dust from being lost.Mashing in (sometimes called "doughing-in") is typically done between 35 and 45C (95 and 113F), but, for single-step infusion mashes, mashing in must be done between 6267C (144153F) for amylases to break down the grain's starch into sugars. The weight-to-weight ratio of strike water and grain varies from12for dark beers in single-step infusions to14or even15, ratios more suitable for light-colored beers and decoction mashing, where much mash water is boiled off.Enzymatic rests[edit]Optimal rest temperatures for major mashing enzymes

Temp CTemp FEnzymeBreaks down

4045 C104.0113.0 F-Glucanase-Glucan

5054 C122.0129.2 FProteaseProtein

6267 C143.6152.6 F-AmylaseStarch

7172 C159.8161.6 F-AmylaseStarch

In step-infusion and decoction mashing, the mash is heated to different temperatures at which specific enzymes work optimally. The table at right shows the optimal temperature ranges for the enzymes brewers pay the most attention to and what material those enzymes break down. There is some contention in the brewing industry as to just what the optimal temperature is for these enzymes, as it is often very dependent on thepHof the mash, and its thickness. A thicker mash acts as a buffer for the enzymes. Once a step is passed, the enzymes active in that step aredenaturedby the increasing heat and become permanently inactive. The time spent transitioning between rests is preferably as short as possible; however, if the temperature is raised more than 1 C per minute, enzymes may be prematurely denatured in the transition layer near heating elements.-Glucanase rest[edit]-glucanis a general term forpolysaccharides, such ascellulose, made up of chains ofglucosemolecules connected by betaglycosidic bonds, as opposed to alphaglycosidic bondsin starch. These are a major constituent of thecell wallof plants, and make up a large part of thebranin grains. A-glucanase restdone at 40C (104F) is practiced in order to break down cell walls and make starches more available, thus raising the extraction efficiency. Should the brewer let this rest go on too long, it is possible that a large amount of -glucan will dissolve into the mash, which can lead to a stuck mash on brew day, and cause filtration problems later in beer production.Protease rest[edit]Proteindegradation via aproteolytic restplays many roles: production of free-amino nitrogen (FAN) for yeast nutrition, freeing of small proteins from larger proteins for foam stability in the finished product, and reduction of haze-causing proteins for easier filtration and increased beer clarity. In all-malt beers, the malt already provides enough protein for good head retention, and the brewer needs to worry more about more FAN being produced than the yeast can metabolize, leading to off flavors. The haze causing proteins are also more prevalent in all-malt beers, and the brewer must strike a balance between breaking down these proteins, and limiting FAN production.Amylase rests[edit]Theamylase restsare responsible for the production of free fermentable and nonfermentable sugar from starch in a mash.Starch is an enormous molecule made up of branching chains of glucose molecules. -amylase breaks down these chains from the end molecules forming links of two glucose molecules, i.e.maltose. -amylase cannot break down the branch points, although some help is found here through low -amylase activity and enzymes such as limit dextrinase. The maltose will be the yeast's main food source during fermentation. During this rest starches also cluster together forming visible bodies in the mash. This clustering eases the lautering process.The -amylase rest is also known as thesaccharification rest, because during this rest the -amylase breaks down the starches from the inside, and starts cutting off links of glucose one to four glucose molecules in length. The longer glucose chains, sometimes calleddextrinsormaltodextrins, along with the remaining branched chains, give body and fullness to the beer.Because of the closeness in temperatures of peak activity of -amylase and -amylase, the two rests are often performed at once, with the time and temperature of the rest determining the ratio of fermentable to nonfermentable sugars in the wort and hence the final sweetness of the fermented drink; a hotter rest gives a fuller-bodied, sweeter beer as -amylase produces more unfermentable sugars. 66C (151F) is a typical rest temperature for apale aleor Germanpilsener, while Bohemian pilsener andmild aleare rested more typically at 6768C (153154F).Decoction "rests"[edit]In decoction mashing, part of the mash is taken out of the mash tun and placed in a cooker, where it is boiled for a period of time. This caramelizes some of the sugars, giving the beer a deeper flavor and color, and frees more starches from the grain, making for a more efficient extraction from the grains. The portion drawn off for decoction is calculated so that the next rest temperature is reached by simply putting the boiled portion back into the mash tun. Before drawing off for decoction, the mash is allowed to settle a bit, and the thicker part is typically taken out for decoction, as the enzymes have dissolved in the liquid, and the starches to be freed are in the grains, not the liquid. This thick mash is then boiled for around 15 minutes, and returned to the mash tun.The mash cooker used in decoction should not be allowed to scorch the mash, but maintaining a uniform temperature in the mash is not a priority. To prevent a scorching of the grains, the brewer must continuously stir the decoction and apply a slow heating.A decoction mash brings out a higher malt profile from the grains and is typically used in Bocks orDoppelbock-style beers.Mash-out[edit]After the enzyme rests, the mash is raised to its mash-out temperature. This frees up about 2% more starch, and makes the mash lessviscous, allowing thelauterto process faster. Although mash temperature and viscosity are roughly inversely proportional, the ability of brewers and distillers to use this relationship is constrained by the fact that -Amylase quickly denatures above 78C (172.4F). Any starches extracted once the mash is brought above this temperature cannot be broken down, and will cause a starch haze in the finished product, or in larger quantities an unpleasantly harsh flavor can develop. Therefore, the mash-out temperature rarely exceeds 78C (172.4F).If the lauter tun is a separate vessel from the mash tun, the mash is transferred to thelautertun at this time. If the brewery has a combination mash-lautertun, the agitator is stopped after mash-out temperature is reached and the mash has mixed enough to ensure a uniform temperature.Advanced Mashing Techniques11/30/-1MASHING 102 ADVANCED MATERIALThe above is a simple overview of mashing and might be sufficient to guide the novice masher through a basic mash. I want to cover some concepts here that help to explain further the process of mashing.In a way, mashing is the natural progression of malting. Both act to take a raw ingredient (barley or malt) and through enzymatic processes reduce the material into sugars that are consumable by yeast. You may be surprised to think of malting as producing sugars, but this is exactly what occurs in the production of caramel malts. Caramel malts, depending on how dark they are, contain sugars already converted for the brewer.A significant part of the mashing process involves protein degradation. Proteins are organic matter of relatively high molecular weight and are composed of amino acids. Amino acids are Natures building blocks and play an important role in healthy yeast metabolism during fermentation. Properly malted and mashed grains will produce a wort that is high in free amino nitrogen (FAN), which ensures a healthy fermentation.Proteins can be grouped into three classes: large, medium, and small. One of the goals of mashing is to break down large proteins into free amino acids while retaining some medium proteins; medium-sized proteins provide beneficial viscosity to the wort, which aids in head retention and mouthfeel. Large and medium proteins are reduced by the action of proteolytic enzymes during the protein rests in a mash program. These rests are typically performed between 112 and 140 F (4460 C). The malting process also reduces proteins, particularly in the production of British pale ale malts. This is one of the reasons it is easier to mash this malt using a single saccharification rest the protein rest has already largely been done by the maltster.Starches are degraded in three steps: gelatinization, liquefaction, and finally saccharification. Liquefaction is the process by which the starch absorbs water, and the process is enzymatically driven by alpha-amylase. It is a slow process in ungelatinized starch but occurs rapidly in gelatinized starch; therefore, liquefaction cannot occur effectively in mashing until the starches are gelatinized (1). Gelatinization is the process by which the starch molecules break open, allowing them to be more readily converted by amylase enzymes.Malt starch is composed of long chains of glucose molecules amylose and amylopectin (see Figure 2). Amylose is built of linear chains of glucose, whereas amylopectin is built of multi-branched chains of glucose units (4). The linear bonds of amylose are connected by 14 carbon links (the number 1 carbon binds with the number 4 carbon with an oxygen molecule between the 1 and 4 carbons). Amylopectin contains both 16 carbon links and 14 links. Beta-amylase breaks the 14 bond, producing maltose, but is incapable of breaking the 16 linkage in amylopectin. The 16 linkage can, however, be broken by alpha-amylase.Rests in the 140s F (low 60s C) will favor beta-amylase activity, which increases the concentration of maltose in the wort and therefore results in higher fermentability. Often, these rests are termed beta rests or maltose rests. Rests in the high 150s F (~70 C) favor alpha-amylase activity and produce a wort higher in dextrin content. Dextrins are not consumable by brewers yeast and survive into the finished beer, providing beneficial mouthfeel.Another issue in mashing is that of beta glucans. Beta glucans are gums that are products of the breakdown of the hemicellulosic cell walls. They are produced during the malting process under the action of the enzyme beta-glucanase. Beta-glucanase enzymes can survive the malting process but are rapidly deactivated above 122 F (50 C). They remain quite active at 104 F (40 C), and as a result a rest in the 104 F (40 C) range will help to dissolve the beta glucans. Beta-glucanase survives to a much higher degree in lightly kilned pale lager malts than in ale malts (2).Beta glucans have an effect on wort viscosity. Higher levels left intact may lead to more-viscous wort and subsequently more difficult lautering. In general, more highly modified malt will have lower levels of beta glucans.Wheat malt, in particular, has high levels of gums and for this reason a low temperature rest is almost mandatory when mashing wheat. Also, because ferrulic acid is liberated at 111 F (44 C), a rest at this temperature is most beneficial for wheat beers. Ferrulic acid binds to pentosanes in grains with ester bonds, and because beta-glucanase degrades both beta glucans and pentosanes, this rest will liberate free ferrulic acid. Free ferrulic acid is important in wheat beers because it is decarboxylized into 4-vinyl guaiacol during fermentation (5), which contributes to the characteristic phenolic flavor.The combination of temperature rests favoring each amylase leads to maximum extract yield. It is also the different characteristics of these amylases that allows brewers to carefully control the composition of the wort and the character of the finished beer.DECOCTION MASHINGDecoction mashing is the traditional technique used in brewing to process undermodified to moderately modified malt, primarily in the production of lagers and Weizens. In decoction mashing, a protein rest is performed at around 122 F (50 C) for 15 min. After this rest, a thick portion of the grains (about 2035%) containing little fluid is removed and separately mashed at saccharification temperatures between 148 and 158 F (6570 C), followed by a 1545 min period of boiling.Significant changes to the malt occur at the elevated mashing temperatures, primarily those between 165 F (74 C) and boiling. Starch molecules that survive into the higher temperatures literally explode, liberating their components and furthering reduction and conversion. Boiling the grains dissolves gums, which are especially troublesome in Weizen beers. Boiling also darkens the wort and helps to further reduce proteins.At the completion of the boil, the decocted portion is combined with the rest of the mash, and the resulting mash is held at saccharification temperatures until conversion is complete. Alternatively, a second or even third decoction may be pulled after the mashes are recombined (double and triple decoction mashing, respectively).At the end of the saccharification period, the mash is raised to mash-off by the addition of heat or a decocted portion of the mash. Decoction mashes usually produce a slightly higher degree of extract and a somewhat maltier flavor. For more complete discussions of decoction mashing, see references 5 and 6.Decoction mashing is losing favor in lager brewing because of its high energy costs and because of the production of ever more highly modified malts. German brewmasters are continually raising the dough-in temperatures to upwards of 140 F (60 C) in an effort to preserve some beneficial proteins that accentuate the foam stand of a beer. This practice is a direct response to the over-modification of modern continental Pils malts.SCIENCE SERVES ARTMashing is a complex mix of enzymatic reactions that each have optimum temperature and pH ranges. It is easy to say that beta-amylase is most active at 140149 F (6065 C), but it is also somewhat active at 154 F (68 C) and even higher temperatures. Similarly, alpha-amylase is most active in the high 150s F (low 70s C), but it survives to some extent into the 170s F (high 70s C). By carefully controlling the time spent at each of the optimum ranges, you can successfully predict wort composition.It is the art of the brewer to devise mash programs that optimize the conversion of the raw malt into wort that meets the requirements of a particular beer style (see Figures 37). Mashing provides the brewer tools that can be used to create both variety and consistent, repeatable results.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 ourForums, 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 inthis thread.- The Editorial TeamA

Acid restan optional rest period during the mash of between fifteen and thirty minutes where thegristis held at 35 - 40C to acidify the mash and aid the action of malt amylases.Adjunctsany 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.Airlocktypically 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 131For example:(1.045-1.009) X 131= Alcohol by Volume.0.036 X 131=Alcohol by Volume.4.716 = Alcohol by Volume.Alebroadly speaking, a beer brewed using a top-fermenting yeast; one that ferments best at warmer temperatures (usually between 16C 24C). (Contrast withLager).Alkalinitythe 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 Brewingthe 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 withKit BrewingandExtract Brewing). See also thisguide to all-grain brewing.Amylasemalt enzyme responsible for the breakdown of malt starch into simpler sugars during mashing.Alpha Acidsacids 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.Autolysisthe 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.

Autosyphona 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.

BBall lockthe 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 maltthe malt that contributes the majority of fermentable sugars in the grist. (Contrast withSpeciality Malt)Batch primingthe 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 sparginga 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 withContinuous sparging).Beer kit seeKit brewingBench capper seeBottle Capper.

Bittering Hopshops added at the beginning of the boil and provide the bitter flavour to beer. (Contrast withAroma 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. Boilerthe 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 aCopperor aKettle.Boiling timethe 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 wanda 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 thisguide to bottling beer.Bottle cappera 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 thisguide 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 bucketa 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 primingsugar is added before bottling to provide carbonation through the action of the entrained yeast.See also thisguide to bottling beer.Break material seeCold breakandHot break.Bungin 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 beltan electric heating belt which can be wrapped around a fermenter.Brewpot seeBoiler.Brixunit of measurement of sugar in wort. Functionally equivalent to degreesPlatoCCalcium an essential component in brewingliquor. 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 seeGypsumCaramel 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 whenpriming.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 seeReal Ale.Chill hazehaze 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 recipea recipe that purports to clone a commercially brewed beer.Cold breakrefers 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 causeChill haze. (Contrast withHot break).Continuous hoppingthe 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, butis generally considered the most efficient sparge method. (Contrast withBatch sparging).Copper seeBoiler.Crystal maltone 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 sugarseeDextrose.Corny kegseeCornelius 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.

D

Decoctiona 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.Demijohna one-gallon glass jar with straight shoulders and two handles at the top. They are often used for smaller experimental batches of beer.Dextroseglucose monohydrate. Can be used as a priming sugar.Dimethyl SulphideCommonly 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 CO2into the headspace.

DMEabbreviation for "Dry Malt Extract" (sometimes referred to as "spray malt"). SeeMalt.DMS seeDimethyl sulphideDoughing-inthe 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.

E

Efficiencythe 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 thisarticle 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 withAll-Grain Brewing). See also thisguide to extract brewing.

F

False bottoma 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 seeAirlock.Fermenter the vessel into which you add the wort and yeast to ferment into beer.Final Gravitythe measure of theSpecific Gravityof 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 seeAroma Hops.First runningsthe 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 hoppingThe 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.Flocculationthe 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 CO2under 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'.

G

Gas burnera 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 withHeating Element).Grain baga fine mesh bag, usually made of nylon or cotton. Typically used by extract brewers to steep specialty grains in the brewing water.Grain bed depththe 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 milla 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.

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

HHead retentionthe 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.Headspacethe 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 CO2produced 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 Systemcommonly 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 withRIMS).Heating Element an electric element attached to the inside of a hot liquor tank or brewpot for heating and boiling the liquid. (Contrast withGas Burner).HERMSseeHeat Exchange Recirculating Mash System.High alpha hopshops 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 kita 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 forkit 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 oilthe 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 Pelletswhole 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 strainera 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.HopsHumulus Lupulus, Cannabinaceafamily.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 withCold Break.Hot liquor tanka 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 aerationa 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.Huskthe 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 Sulphidea 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.

IIBUseeInternational bittering unit.Immersion chillerseeWort Chiller.Infectionthe presence of micro organisms in sufficient numbers, other than the pitched yeast strain, to taint the beer with off flavours. SeeWild YeastInfusion mashThe 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 withDecoction).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 withAlpha 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 Acidsthe form that alpha acids take afterisomerisationduring the boil. They provide the bitterness in beer.Isomerisationa chemical process in which a molecule is rearranged in structure, but still contains the same number of atoms.

KKeg conversionany 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