Mashing
Encyclopedia
In brewing
and distilling, mashing is the process of combining a mix of milled grain
(typically malt
ed barley
with supplementary grains
such as corn
, sorghum
, rye
or wheat
), known as the "grain bill", and water, known as "liquor", and heating this mixture. Mashing allows the enzyme
s in the malt to break down the starch
in the grain into sugar
s, typically maltose
to create a malty liquid called wort
. There are two main methods - infusion
mashing, in which the grains are heated in one vessel; and decoction
mashing, in which a proportion of the grains are boiled and then returned to the mash, raising the temperature. Mashing involves pauses at certain temperatures (notably 45 °C, 62 °C and 73 °C) [113°F, 144°F, and 163°F], and takes place in a "mash tun" - an insulated brewing vessel with a false bottom. The end product of mashing is called a "mash".
mashing, 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 before lautering
.
mashing 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. It is a traditional method, and is common in German and Central European breweries. It was used out of necessity before the invention of thermometers allowed simpler step mashing. But the practice continues for many traditional beer
s because of the unique malty flavor it lends to the beer; boiling part of the grain results in Maillard reaction
s leading to malty flavours.
, to keep the temperature of the mash uniform, and a heating device which is efficient, but will not scorch the malt (often steam), and should be insulated
to maintain rest temperatures for up to one hour. A spray ball for clean-in-place (CIP) operation should also be included for periodic deep cleaning. Sanitation is not a major concern before wort boiling, so a rinse-down should be all that is necessary between batches.
Smaller breweries will often use a boil kettle or a lauter tun for mashing. The latter case either limits the brewer to single-step infusion mashing, or leaves the brewer with a lauter tun which is not completely appropriate for the lautering
process.
content of a grain refers to the mass fraction of the grain which is made up of protein
, and is usually expressed as a percentage
; this fraction is further refined by distinguishing what fraction of the protein is water-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 of glassware
for presenting serving beverages; traditional styles such as sahti
, saison
, and bière de garde
, as well as several Belgian 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 a protease
rest.
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.
s, grains which have begun to germinate; the act of germination includes the production of a number of enzymes such as amylase
which convert starch
into sugar; thereby, sugars can be extracted from the barley's own starches simply by soaking the grain in water at a controlled temperature: this is mashing. Other enzymes break long proteins into short ones and accomplish other important tasks.
In general, the hotter a grain is kilned, the less its diastatic activity; consequently, only lightly colored grains can be used as base malts, with Munich malt being 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 degrees Lintner (°Lintner
or °L, although the latter can conflict with the symbol °L for Lovibond color); or in Europe by Windisch-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, American six-row pale barley malts, 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.
(SRM), Lovibond (°L), American Society of Brewing Chemists
(ASBC) or European 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 in homebrewing
circles as the easiest to implement without a spectrophotometer. The darkness of grains range from as light as 3 SRM/5 EBC for Pilsener malt to as dark as 700 SRM/1600 EBC for black malt and roasted barley.
. Milling increases the surface area of the grain, making the starch more accessible, and separates the seed from the husk
. 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 mills
Two-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 mills
Four-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 mills
Six-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 basically six-roller mills in which one of the rollers performs double-duty.
Mashing in is typically done between 35°C and 45°C (95°F and 113°F), but for single-step infusion mashes mashing in must be done between 62 °C and 67 °C (143.6°F and 152.6°F) for amylases to break down the grain's starch into sugars. The weight-to-weight ratio of strike water and grain varies from 1:2 for dark beers in single-step infusions to 1:4 or even 1:5, ratios more suitable for light-colored beers and decoction mashing, where much mash water is boiled off.
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 for the enzymes brewers most pay 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 the pH
of 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 are denatured, and become permanently inactive. The time between rests is preferably as short as possible, but if the temperature is raised more than 1 °C per minute, enzymes may be prematurely denatured in the transition layer near heating elements.
molecules, and found mainly in the cell walls of plants, and in this context is also known as cellulose
. A β-glucanase rest done at 40°C (104°F) 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 β-glucan will dissolve into the mash, which can lead to a stuck mash on brew day, and cause filtration problems later in beer production.
degradation via a proteolytic rest plays 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.
Starch is an enormous molecule made up of branching chains of glucose molecules. β-amylase breaks down these chains from the end molecules forming links of two glucose molecules, i.e. maltose
. β-amylase cannot break down the branch points, although some help is found here through low α-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 α-amylase rest is also known as the saccharification rest, because during this rest the α-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 called dextrin
s or maltodextrins, along with the remaining branched chains, give body and fullness to the beer.
Because of the closeness in temperatures of peak activity of α-amylase and β-amylase, the two rests are often performed at once, with the exact 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 also a fuller-bodied, sweeter beer as α-amylase produces more unfermentable sugars. 66°C (151°F) is a typical rest temperature for a pale ale
or German pilsener
, while Bohemian pilsener and mild ale
are rested more typically at 67-68°C (153 - 154°F).
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 or Doppelbock style beers.
, allowing the lauter
to 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 α-Amylase quickly denatures above 78°C (172.4°F). Any starches extracted 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 78°C (172.4°F).
If the lauter tun is a separate vessel from the mash tun, the mash is transferred to the lauter
tun at this time. If the brewery has a combination mash-lauter
tun, the agitator is stopped after mash-out temperature is reached and the mash has mixed enough to ensure a uniform temperature.
Brewing
Brewing is the production of beer through steeping a starch source in water and then fermenting with yeast. Brewing has taken place since around the 6th millennium BCE, and archeological evidence suggests that this technique was used in ancient Egypt...
and distilling, mashing is the process of combining a mix of milled grain
GRAIN
GRAIN is a small international non-profit organisation that works to support small farmers and social movements in their struggles for community-controlled and biodiversity-based food systems. Our support takes the form of independent research and analysis, networking at local, regional and...
(typically malt
Malt
Malt is germinated cereal grains that have been dried in a process known as "malting". The grains are made to germinate by soaking in water, and are then halted from germinating further by drying with hot air...
ed barley
Barley
Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, as a base malt for beer and certain distilled beverages, and as a component of various health foods...
with supplementary grains
Adjunct
Adjunct may refer to:* Adjunct , words used as modifiers* Adjunct professor, a professor who does not hold a permanent position at a particular academic institution* Adjuncts, sources of sugar used in brewing...
such as corn
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
, sorghum
Sorghum
Sorghum is a genus of numerous species of grasses, one of which is raised for grain and many of which are used as fodder plants either cultivated or as part of pasture. The plants are cultivated in warmer climates worldwide. Species are native to tropical and subtropical regions of all continents...
, rye
Rye
Rye is a grass grown extensively as a grain and as a forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye grain is used for flour, rye bread, rye beer, some whiskeys, some vodkas, and animal fodder...
or wheat
Wheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
), known as the "grain bill", and water, known as "liquor", and heating this mixture. Mashing allows the enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s in the malt to break down the starch
Starch
Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...
in the grain into sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
s, typically maltose
Maltose
Maltose , or malt sugar, is a disaccharide formed from two units of glucose joined with an αbond, formed from a condensation reaction. The isomer "isomaltose" has two glucose molecules linked through an α bond. Maltose is the second member of an important biochemical series of glucose chains....
to create a malty liquid called wort
Wort
Wort may refer to:* Wort, the liquid created by the mashing of malted barley to use in brewing beer* Worting, Hampshire, a large district and suburb of the town of Basingstoke, in Hampshire, England....
. There are two main methods - infusion
Infusion
An infusion is the outcome of steeping plants with desired chemical compounds or flavors in water or oil.-History:The first recorded use of essential oils was in the 10th or 11th century by the Persian polymath Avicenna, possibly in The Canon of Medicine.-Preparation techniques:An infusion is very...
mashing, in which the grains are heated in one vessel; and decoction
Decoction
Decoction is a method of extraction, by boiling, of dissolved chemicals, or herbal or plant material, which may include stems, roots, bark and rhizomes. Decoction involves first mashing, and then boiling in water to extract oils, volatile organic compounds, and other chemical substances...
mashing, in which a proportion of the grains are boiled and then returned to the mash, raising the temperature. Mashing involves pauses at certain temperatures (notably 45 °C, 62 °C and 73 °C) [113°F, 144°F, and 163°F], and takes place in a "mash tun" - an insulated brewing vessel with a false bottom. The end product of mashing is called a "mash".
Infusion mashing
Most breweries use infusionInfusion
An infusion is the outcome of steeping plants with desired chemical compounds or flavors in water or oil.-History:The first recorded use of essential oils was in the 10th or 11th century by the Persian polymath Avicenna, possibly in The Canon of Medicine.-Preparation techniques:An infusion is very...
mashing, 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 before lautering
Lautering
Lautering is a process in brewing beer in which the mash is separated into the clear liquid wort and the residual grain. Lautering usually consists of 3 steps: mashout, recirculation, and sparging.-Mashout:...
.
Decoction mashing
DecoctionDecoction
Decoction is a method of extraction, by boiling, of dissolved chemicals, or herbal or plant material, which may include stems, roots, bark and rhizomes. Decoction involves first mashing, and then boiling in water to extract oils, volatile organic compounds, and other chemical substances...
mashing 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. It is a traditional method, and is common in German and Central European breweries. It was used out of necessity before the invention of thermometers allowed simpler step mashing. But the practice continues for many traditional beer
Beer
Beer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...
s because of the unique malty flavor it lends to the beer; boiling part of the grain results in Maillard reaction
Maillard reaction
The Maillard reaction is a form of nonenzymatic browning similar to caramelization. It results from a chemical reaction between an amino acid and a reducing sugar, usually requiring heat....
s leading to malty flavours.
Mash tun
In large breweries, in which optimal utilization of the brewery equipment is economically necessary, there is at least one dedicated vessel for mashing. In decoction processes there must be at least two. The vessel has a good stirring mechanism, a mash rakeMash rake
A mash rake or mashing rake is a tool used in the mashing process of brewing and distilling. The mash rake churns the mash to ensure it is mixed properly and is wet everywhere, so no sugars are wasted....
, to keep the temperature of the mash uniform, and a heating device which is efficient, but will not scorch the malt (often steam), and should be insulated
Thermal insulation
Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...
to maintain rest temperatures for up to one hour. A spray ball for clean-in-place (CIP) operation should also be included for periodic deep cleaning. Sanitation is not a major concern before wort boiling, so a rinse-down should be all that is necessary between batches.
Smaller breweries will often use a boil kettle or a lauter tun for mashing. The latter case either limits the brewer to single-step infusion mashing, or leaves the brewer with a lauter tun which is not completely appropriate for the lautering
Lautering
Lautering is a process in brewing beer in which the mash is separated into the clear liquid wort and the residual grain. Lautering usually consists of 3 steps: mashout, recirculation, and sparging.-Mashout:...
process.
Ingredient selection
Each particular ingredient has its own flavor which 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
The nitrogenNitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
content of a grain refers to the mass fraction of the grain which is made up of protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
, and is usually expressed as a percentage
Percentage
In mathematics, a percentage is a way of expressing a number as a fraction of 100 . It is often denoted using the percent sign, “%”, or the abbreviation “pct”. For example, 45% is equal to 45/100, or 0.45.Percentages are used to express how large/small one quantity is, relative to another quantity...
; this fraction is further refined by distinguishing what fraction of the protein is water-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 of glassware
Glassware
This list of glassware includes drinking vessels , tableware, such as dishes, and flatware used to set a table for eating a meal, general glass items such as vases, and glasses used in the catering industry whether made of glass or plastics such as polystyrene and...
for presenting serving beverages; traditional styles such as sahti
Sahti
Sahti is a traditional beer from Finland made from a variety of grains, malted and unmalted, including barley, rye, wheat, and oats; sometimes bread made from these grains is fermented instead of malt itself...
, saison
Saison
Saison is the name originally given to low-alcohol pale ales brewed seasonally in farmhouses in Wallonia, the French-speaking region of Belgium, for farm workers during harvest season...
, and bière de garde
Bière de Garde
Bière de Garde is a strong pale ale or keeping beer traditionally brewed in the Nord-Pas-de-Calais region of France. These beers were originally brewed in farmhouses during the winter and spring, to avoid unpredictable problems with the yeast during the summertime...
, as well as several Belgian styles
Belgian beer
Beer in Belgium varies from pale lager to lambic beer and Flemish red. There are approximately 178 breweries in the country, ranging from international giants to microbreweries..-History:...
, 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 a protease
Protease
A protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein....
rest.
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
The diastatic power (DP), also called the "diastatic activity" or "enzymatic power", of a grain generally refers only to maltMalt
Malt is germinated cereal grains that have been dried in a process known as "malting". The grains are made to germinate by soaking in water, and are then halted from germinating further by drying with hot air...
s, grains which have begun to germinate; the act of germination includes the production of a number of enzymes such as amylase
Amylase
Amylase is an enzyme that catalyses the breakdown of starch into sugars. Amylase is present in human saliva, where it begins the chemical process of digestion. Food that contains much starch but little sugar, such as rice and potato, taste slightly sweet as they are chewed because amylase turns...
which convert starch
Starch
Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...
into sugar; thereby, sugars can be extracted from the barley's own starches simply by soaking the grain in water at a controlled temperature: this is mashing. Other enzymes break long proteins into short ones and accomplish other important tasks.
In general, the hotter a grain is kilned, the less its diastatic activity; consequently, only lightly colored grains can be used as base malts, with Munich malt being 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 degrees Lintner (°Lintner
°Lintner
°Lintner or degrees Lintner is a unit used to measure the ability of a malt to reduce starch to sugar, that is, its diastatic power. While the measurement is applicable to any amylase, in general it refers to the combined α-amylase and β-amylase used in brewing. The term is also generalized to...
or °L, although the latter can conflict with the symbol °L for Lovibond color); or in Europe by Windisch-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, American six-row pale barley malts, 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
In brewing, the color of a grain or product is evaluated by the Standard Reference MethodStandard Reference Method
The Standard Reference Method or SRM is one of several systems modern brewers use to specify beer color. Determination of the SRM value involves measuring the attenuation of light of a particular wavelength in passing through 1 cm of the beer, expressing the attenuation as an absorption and...
(SRM), Lovibond (°L), American Society of Brewing Chemists
American Society of Brewing Chemists
The ASBC is a professional organization of scientists and technical professionals in the brewing, malting, and allied industries. It publishes a journal, the Journal of the American Society of Brewing Chemists, usually four times a year....
(ASBC) or European Brewery Convention
European Brewery Convention
European Brewery Convention is an organisation of technical experts for European brewers and maltsters, and the scientific and technological branch of The Brewers of Europe....
(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 in homebrewing
Homebrewing
Homebrewing is the brewing of beer, wine, sake, mead, cider, perry and other beverages through fermentation on a small scale as a hobby for personal consumption, free distribution at social gatherings, amateur brewing competitions or other non-commercial reasons...
circles as the easiest to implement without a spectrophotometer. The darkness of grains range from as light as 3 SRM/5 EBC for Pilsener malt to as dark as 700 SRM/1600 EBC for black malt and roasted barley.
Modification
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
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
The grain used for making beer must first be milledMill (grinding)
A grinding mill is a unit operation designed to break a solid material into smaller pieces. There are many different types of grinding mills and many types of materials processed in them. Historically mills were powered by hand , working animal , wind or water...
. Milling increases the surface area of the grain, making the starch more accessible, and separates the seed from the husk
Husk
Husk in botany is the outer shell or coating of a seed. It often refers to the leafy outer covering of an ear of maize as it grows on the plant. Literally, a husk or hull includes the protective outer covering of a seed, fruit or vegetable...
. 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 mills
Two-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 mills
Four-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 mills
Six-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 basically six-roller mills in which one of the rollers performs double-duty.
Mashing-in
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. Traditionally this was 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 unfortunately 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 is typically done between 35°C and 45°C (95°F and 113°F), but for single-step infusion mashes mashing in must be done between 62 °C and 67 °C (143.6°F and 152.6°F) for amylases to break down the grain's starch into sugars. The weight-to-weight ratio of strike water and grain varies from 1:2 for dark beers in single-step infusions to 1:4 or even 1:5, ratios more suitable for light-colored beers and decoction mashing, where much mash water is boiled off.
Enzymatic rests
| Temp °C | Temp °F | Enzyme | Breaks down |
|---|---|---|---|
| 40-45 °C | 104.0 °F | β-Glucanase | β-Glucan |
| 50-54 °C | 122.0 °F | Protease | Protein |
| 62-67 °C | 143.6 °F | β-Amylase | Starch |
| 71-72 °C | 161.6 °F | α-Amylase | Starch |
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 for the enzymes brewers most pay 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 the pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
of 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 are denatured, and become permanently inactive. The time between rests is preferably as short as possible, but if the temperature is raised more than 1 °C per minute, enzymes may be prematurely denatured in the transition layer near heating elements.
β-glucanase rest
β-glucan is a chain of the beta isomer of glucoseGlucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
molecules, and found mainly in the cell walls of plants, and in this context is also known as cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
. A β-glucanase rest done at 40°C (104°F) 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 β-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
ProteinProtein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
degradation via a proteolytic rest plays 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
The amylase rests are 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. β-amylase breaks down these chains from the end molecules forming links of two glucose molecules, i.e. maltose
Maltose
Maltose , or malt sugar, is a disaccharide formed from two units of glucose joined with an αbond, formed from a condensation reaction. The isomer "isomaltose" has two glucose molecules linked through an α bond. Maltose is the second member of an important biochemical series of glucose chains....
. β-amylase cannot break down the branch points, although some help is found here through low α-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 α-amylase rest is also known as the saccharification rest, because during this rest the α-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 called dextrin
Dextrin
Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch or glycogen. Dextrins are mixtures of polymers of D-glucose units linked by α- or α- glycosidic bonds....
s or maltodextrins, along with the remaining branched chains, give body and fullness to the beer.
Because of the closeness in temperatures of peak activity of α-amylase and β-amylase, the two rests are often performed at once, with the exact 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 also a fuller-bodied, sweeter beer as α-amylase produces more unfermentable sugars. 66°C (151°F) is a typical rest temperature for a pale ale
Pale ale
Pale ale is a beer which uses a warm fermentation and predominantly pale malt. It is one of the world's major beer styles.The higher proportion of pale malts results in a lighter colour. The term "pale ale" was being applied around 1703 for beers made from malts dried with coke, which resulted in a...
or German pilsener
Pilsener
Pilsner is a type of pale lager. It takes its name from the city of Pilsen , Bohemia, in today's Czech Republic, where it has been developed since 1842, when a bottom-fermented beer was first produced. The original Pilsner Urquell beer is produced there today.-Origin:Until the mid-1840s, most ...
, while Bohemian pilsener and mild ale
Mild ale
Mild ale is a low-gravity beer, or beer with a predominantly malty palate, that originated in Britain in the 17th century or earlier. Modern mild ales are mainly dark coloured with an abv of 3% to 3.6%, though there are lighter hued examples, as well as stronger examples reaching 6% abv and...
are rested more typically at 67-68°C (153 - 154°F).
Decoction "rests"
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 or Doppelbock style beers.
Mash-out
After the enzyme rests, the mash is raised to its mash out temperature. This frees up about 2% more starch, and makes the mash less viscousViscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
, allowing the lauter
Lautering
Lautering is a process in brewing beer in which the mash is separated into the clear liquid wort and the residual grain. Lautering usually consists of 3 steps: mashout, recirculation, and sparging.-Mashout:...
to 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 α-Amylase quickly denatures above 78°C (172.4°F). Any starches extracted 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 78°C (172.4°F).
If the lauter tun is a separate vessel from the mash tun, the mash is transferred to the lauter
Lautering
Lautering is a process in brewing beer in which the mash is separated into the clear liquid wort and the residual grain. Lautering usually consists of 3 steps: mashout, recirculation, and sparging.-Mashout:...
tun at this time. If the brewery has a combination mash-lauter
Lautering
Lautering is a process in brewing beer in which the mash is separated into the clear liquid wort and the residual grain. Lautering usually consists of 3 steps: mashout, recirculation, and sparging.-Mashout:...
tun, the agitator is stopped after mash-out temperature is reached and the mash has mixed enough to ensure a uniform temperature.