Ingredients
used in beer making
The
basic ingredients of beer are water; a starch source, such as malted barley,
able to be saccharified (converted to sugars) then fermented (converted into
alcohol and carbon dioxide); a brewer’s yeast to produce the fermentation; and
a flavouring such as hops A mixture of starch sources may be used, with a
secondary starch source, such as maize (corn), rice or sugar, often being
termed an adjunct, especially when used as a lower-cost substitute for malted
barley. Less widely used starch sources include millet, sorghum and cassava
root in Africa, and potato in Brazil, and agave in Mexico, among other The
amount of each starch source in a beer recipe is collectively called the grain
bill.
Water
Beer 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.[ For example, Dublin has
hard water well-suited to making stout, such as Guinness; while Pilzen has soft
water well-suited to making pale lager, such as Pilsner Urquell. The waters of
Burton in England contain gypsum, which benefits making pale ale to such a
degree that brewers of pale ales will add gypsum to the local water in a
process known as Burtonisation.
Starch
source
The
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 begin germination, and then drying the partially germinated
grain in a kiln. Malting grain produces enzymes that convert starches in the
grain into fermentable sugars. Different roasting times and temperatures are
used to produce different colours of malt from the same grain. Darker malts
will produce darker beers.[
Nearly all beer includes barley malt as the majority of the starch. This is because its fibrous hull remains attached to the grain during threshing. After malting, barley is milled, which finally removes the hull, breaking it into large pieces. These pieces remain with the grain during the mash, and act as a filter bed during lautering, when sweet wort is separated from insoluble grain material. Other malted and unmalted grains (including wheat, rice, oats, and rye, and less frequently, corn and sorghum) may be used. In recent years, a few brewers have produced gluten-free beer, made with sorghum with no barley malt, for those who cannot consume gluten-containing grains like wheat, barley, and rye.
Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, a source of fermentable material for beer and certain distilled beverages, and as a component of various health foods. It is used in soups and stews, and in barley bread of various cultures. Barley grains are commonly made into malt in a traditional and ancient method of preparation.
Nearly all beer includes barley malt as the majority of the starch. This is because its fibrous hull remains attached to the grain during threshing. After malting, barley is milled, which finally removes the hull, breaking it into large pieces. These pieces remain with the grain during the mash, and act as a filter bed during lautering, when sweet wort is separated from insoluble grain material. Other malted and unmalted grains (including wheat, rice, oats, and rye, and less frequently, corn and sorghum) may be used. In recent years, a few brewers have produced gluten-free beer, made with sorghum with no barley malt, for those who cannot consume gluten-containing grains like wheat, barley, and rye.
Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, a source of fermentable material for beer and certain distilled beverages, and as a component of various health foods. It is used in soups and stews, and in barley bread of various cultures. Barley grains are commonly made into malt in a traditional and ancient method of preparation.
Two-row
and six-row barley
Two-row
barley has a lower protein content than six-row barley, thus more fermentable
sugar content. High protein barley is best suited for animal feed. Malting
barley is usually lower protein[8] (‘low grain nitrogen’, usually produced
without a late fertilizer application) which shows more uniform germination,
needs shorter steeping, and has less protein in the extract that can make beer
cloudy. Two-row barley is traditionally used in English ale-style beers.
Six-row barley is common in some American lager style beers, especially when
adjuncts such as corn and rice are used, whereas two-row malted summer barley
is preferred for traditional German beer
Classification
of barley
In
traditional classifications of barley, these morphological differences have led
to different forms of barley being classified as different species. Under these
classifications, two-rowed barley with shattering spikes (wild barley) is
classified as Hordeum spontaneu. Two-rowed barley with nonshattering spikes is
classified as H. distichum L., six-row barley with nonshattering spikes as H.
vulgare L. (or H. hexastichum L.), and six-row with shattering spikes as H.
agriocrithon.
Hops
The hop
plant is a vigorous, climbing, herbaceous perennial, usually trained to grow up
strings in a field called a hopfield, hop garden, or hop yard when grown
commercially. Many different types of hops are grown by farmers around the
world, with different types being used for particular styles of beer.
Hops
are the female flower clusters (commonly called seed cones or strobiles), of a
hop species, Humulus lupulus They are used primarily as a flavoring and
stability agent in beer, to which they impart a bitter, tangy flavor, though
hops are also used for various purposes in other beverages and herbal medicine.
Hops are used extensively in brewing for their many purported benefits,
including balancing the sweetness of the malt with bitterness, contributing a
variety of desirable flavors and aromas, and having an antibacterial effect
that favors the activity of brewer’s yeast over less desirable microorganisms.
Historically, traditional herb combinations for ales were believed to have been
abandoned when ales made with hops were noticed to be less prone to spoilage.[
Flavouring beer is the sole major commercial use of hops. The flower of the hop vine is used as a flavouring and preservative agent in nearly all beer made today. The flowers themselves are often called “hops”.
The date normally given for widespread cultivation of hops for use in beer is the thirteenth century. Before the thirteenth century, and until the sixteenth century, during which hops took over as the dominant flavouring, beer was flavoured with other plants. Combinations of various aromatic herbs, berries, and even ingredients like wormwood would be combined into a mixture known as gruit and used as hops are now used. Some beers today, such as Fraoch’ by the Scottish Heather Ales company and Cervoise Lancelot by the French Brasserie-Lancelot company use plants other than hops for flavouring.
Hops contain several characteristics that brewers desire in beer. Hops contribute a bitterness that balances the sweetness of the malt; the bitterness of beers is measured on the International Bitterness Units scale. Hops contribute floral, citrus, and herbal aromas and flavours to beer. Hops have an antibiotic effect that favours the activity of brewer’s yeast over less desirable microorganisms and aids in “head retention” the length of time that a foamy head created by carbonation will last. The acidity of hops is a preservative.
Flavouring beer is the sole major commercial use of hops. The flower of the hop vine is used as a flavouring and preservative agent in nearly all beer made today. The flowers themselves are often called “hops”.
The date normally given for widespread cultivation of hops for use in beer is the thirteenth century. Before the thirteenth century, and until the sixteenth century, during which hops took over as the dominant flavouring, beer was flavoured with other plants. Combinations of various aromatic herbs, berries, and even ingredients like wormwood would be combined into a mixture known as gruit and used as hops are now used. Some beers today, such as Fraoch’ by the Scottish Heather Ales company and Cervoise Lancelot by the French Brasserie-Lancelot company use plants other than hops for flavouring.
Hops contain several characteristics that brewers desire in beer. Hops contribute a bitterness that balances the sweetness of the malt; the bitterness of beers is measured on the International Bitterness Units scale. Hops contribute floral, citrus, and herbal aromas and flavours to beer. Hops have an antibiotic effect that favours the activity of brewer’s yeast over less desirable microorganisms and aids in “head retention” the length of time that a foamy head created by carbonation will last. The acidity of hops is a preservative.
Species
There
are three species of hops
• Humulus japonicus (syn. H. scandens). Asian Hop. Leaves with 5–7 lobes. Eastern Asia.
• Humulus lupulus. Common Hop. Leaves with 3–5 lobes. Europe, western Asia, North America.
• Humulus yunnanensis. Yunnan Hop. Leaves with 3–5 lobes, densely hairy below. Southeast Asia (endemic in Yunnan, China).
• Humulus japonicus (syn. H. scandens). Asian Hop. Leaves with 5–7 lobes. Eastern Asia.
• Humulus lupulus. Common Hop. Leaves with 3–5 lobes. Europe, western Asia, North America.
• Humulus yunnanensis. Yunnan Hop. Leaves with 3–5 lobes, densely hairy below. Southeast Asia (endemic in Yunnan, China).
Hop
varieties
.
Particular hop varieties are associated with beer regions and styles, for
example pale lagers are usually brewed with European (often German and
Austrian, since 1981 also Czech) noble hop varieties such as Saaz, Hallertau
and Strissel Spalt. British ales use hop varieties such as Fuggles, Goldings
and Bullion. North American beers use Cascade hops, Columbus hops, Centennial
hops, Willamette hops and Amarillo hops.
Noble
hops
The
term “noble hops” traditionally refers to four varieties of hops which are low
in bitterness and high in aroma. They are the central European cultivars,
Hallertau, Tettnanger, Spalt, and Saaz. They are each named for a specific
region or city in which they were first grown or primarily grown. They contain
high amounts of the hop oil humulene and low amounts of alpha acids cohumulone
and adhumulone, as well as lower amounts of the harsher-tasting beta acids
lupulone, colupulone, and adlupulone.
Yeast
Yeast
is the microorganism that is responsible for fermentation in beer. Yeast
metabolises the sugars extracted from grains, which produces alcohol and carbon
dioxide, and thereby turns wort into beer. In addition to fermenting the beer,
yeast influences the character and flavour. The dominant types of yeast used to
make beer are the top-fermenting Saccharomyces cerevisiae and bottom-fermenting
Saccharomyces uvarum.[ Brettanomyces ferments lambics, and Torulaspora
delbrueckii ferments Bavarian weissbier.[ Before the role of yeast in
fermentation was understood, fermentation involved wild or airborne yeasts. A
few styles such as lambics rely on this method today, but most modern
fermentation adds pure yeast cultures.
Brewing yeasts may be classed as “top cropping” (or “top-fermenting”) and “bottom-cropping” (or “bottom-fermenting”).Top cropping yeasts are so called because they form a foam at the top of the wort during fermentation. An example of top-cropping yeast is Saccharomyces cerevisiae, sometimes called an “ale yeast”. Bottom-cropping yeasts are typically used to produce lager-type beers, though they can also produce ale-type beers. These yeasts ferment well at low temperatures. An example of bottom-cropping yeast is Saccharomyces pastorianus, formerly known as S. carlsbergensis.
Brewing yeasts may be classed as “top cropping” (or “top-fermenting”) and “bottom-cropping” (or “bottom-fermenting”).Top cropping yeasts are so called because they form a foam at the top of the wort during fermentation. An example of top-cropping yeast is Saccharomyces cerevisiae, sometimes called an “ale yeast”. Bottom-cropping yeasts are typically used to produce lager-type beers, though they can also produce ale-type beers. These yeasts ferment well at low temperatures. An example of bottom-cropping yeast is Saccharomyces pastorianus, formerly known as S. carlsbergensis.
Clarifying
agent.
Some
brewers add one or more clarifying agents to beer, which typically precipitate
(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
appear bright and clean, rather than the cloudy appearance of ethnic and older
styles of beer such as wheat beers.
Examples of clarifying agents include isinglass, obtained from swim bladders of fish; Irish moss, a seaweed; kappa carrageenan, from the seaweed Kappaphycus cottonii; Polyclar (artificial); and gelatin. If a beer is marked “suitable for Vegans”, it was clarified either with seaweed or with artificial agents.
Examples of clarifying agents include isinglass, obtained from swim bladders of fish; Irish moss, a seaweed; kappa carrageenan, from the seaweed Kappaphycus cottonii; Polyclar (artificial); and gelatin. If a beer is marked “suitable for Vegans”, it was clarified either with seaweed or with artificial agents.
The
brewing process
Beer
production involves malting, milling, mashing, extra ct separation, hop
addition and boiling, removal of hops and precipitates, cooling and aeration ,
fermentation, separation of yeast from young beer, ageing, maturing, and
packaging. The object of the entire process is to convert grain starches to
sugar, extract the sugar with water and then ferment it with yeast to produce
the alcoholic and lightly carbonated beverage
Malting
Malting
modifies barley to green malt, which can then be preserved by drying. The
process involves steeping and aerating the barley, allowing it to germinate,
and drying and curing the malt.
In order to be fermented by yeast, the food reserve of barley, starch, must be converted by enzymes into simple sugars. Two enzymes, α- and β-amylases, carry out the conversion. The latter is present in barley, but the former is made only during germination of the grain. Specially bred strains of barley (generally low in nitrogen content) are used for malting. Other important characteristics are yield, even germination, ability to produce enzymes, and a highly extractable malt.
In order to be fermented by yeast, the food reserve of barley, starch, must be converted by enzymes into simple sugars. Two enzymes, α- and β-amylases, carry out the conversion. The latter is present in barley, but the former is made only during germination of the grain. Specially bred strains of barley (generally low in nitrogen content) are used for malting. Other important characteristics are yield, even germination, ability to produce enzymes, and a highly extractable malt.
Steeping
Malting
begins by immersing barley, harvested at less than 12 percent moisture, in
water at 12 to 15 °C (55 to 60 °F) for 40 to 50 hours. During this steeping
period, the barley may be drained and given air rests, or the steep may be
forcibly aerated. As the grain imbibes water, its volume increases by about 25
percent, and its moisture content reaches about 45 percent. A white root
sheath, called a chit, breaks through the husk, and the chitted barley is then
removed from the steep for germination.
Germination
Activated
by water and oxygen, the root embryo of the barleycorn secretes a plant hormone
called gibberellic acid, which initiates the synthesis of α-amylase. The α- and
β-amylases then convert the starch molecules of the corn into sugars that the
embryo can use as food. Other enzymes, such as the proteases and β-glucanases,
attack the cell walls around the starch grains, converting insoluble proteins
and complex sugars (called glucans) into soluble amino acids and glucose. These
enzymatic reactions are called modification. The more germination proceeds, the
greater the modification. Over modification leads to malting loss, in which
rootlet growth and plant respiration reduce the weight of the grain.
In traditional malting, the steeped barley was placed in heaps called couches and, after 24 hours, spread on a floor to permit germination. Because respiration of the grain causes oxygen to be taken up and carbon dioxide and heat to be produced, control of aeration, ventilation, and temperature was achieved by manually turning the grain. Large-scale floor maltings with mechanical turners were introduced, later replaced by pneumatic maltings, in which germination occurred in boxes with the bed automatically turned, aerated, and ventilated with forced air. In some malting operations, gibberellic acid is sprayed onto the barley to speed germination, and bromates are used to suppress rootlet growth and malting loss. Although less-modified malts are traditionally used in lagers and well-modified malts in ales, it is now usual to produce well-modified malts regardless of whether lager or ale is to be made.
In traditional malting, the steeped barley was placed in heaps called couches and, after 24 hours, spread on a floor to permit germination. Because respiration of the grain causes oxygen to be taken up and carbon dioxide and heat to be produced, control of aeration, ventilation, and temperature was achieved by manually turning the grain. Large-scale floor maltings with mechanical turners were introduced, later replaced by pneumatic maltings, in which germination occurred in boxes with the bed automatically turned, aerated, and ventilated with forced air. In some malting operations, gibberellic acid is sprayed onto the barley to speed germination, and bromates are used to suppress rootlet growth and malting loss. Although less-modified malts are traditionally used in lagers and well-modified malts in ales, it is now usual to produce well-modified malts regardless of whether lager or ale is to be made.
Kilning
Green
malt is dried to remove most of the moisture, leaving 5 percent in lager and 2
percent in traditional ale malts. This process arrests enzyme activity but
leaves 40 to 60 percent in an active state. Curing at higher temperatures
promotes a reaction between amino acids and sugars to form melanoidins, which
give both colour and flavour to malt.
In the first stage of kilning, a high flow of dry air at 50 °C (120 °F) for lager malt and 65 °C (150 °F) for ale malt is maintained through a bed of green malt. This lowers the moisture content from 45 to 25 percent. A second stage of drying removes more firmly bound water, the temperature rising to 70–75 °C (160–170 °F) and the moisture content falling to 12 percent. In the final curing stage, the temperature is raised to 75–90 °C (170–195 °F) for lager and 90–105 °C (195–220 °F) for ale. The finished malt is then cooled and screened to remove rootlets.
Special malts are made by wetting and heating green malt in closed drums at high temperatures. Made in this way are crystal (caramel), chocolate (black), and amber malts; used in small and varying proportions (2 to 3 percent of brewing malt), they introduce considerable variations in colour and flavour to finished beers. Chocolate malt and roasted ungerminated barley are used at a high proportion (25 percent) to make stouts and porters. The use of unmalted cereals has also become common, because they are less expensive sources of starch and can be used to dilute malt colour and flavour, thereby yielding fresher, lighter beers.
In the first stage of kilning, a high flow of dry air at 50 °C (120 °F) for lager malt and 65 °C (150 °F) for ale malt is maintained through a bed of green malt. This lowers the moisture content from 45 to 25 percent. A second stage of drying removes more firmly bound water, the temperature rising to 70–75 °C (160–170 °F) and the moisture content falling to 12 percent. In the final curing stage, the temperature is raised to 75–90 °C (170–195 °F) for lager and 90–105 °C (195–220 °F) for ale. The finished malt is then cooled and screened to remove rootlets.
Special malts are made by wetting and heating green malt in closed drums at high temperatures. Made in this way are crystal (caramel), chocolate (black), and amber malts; used in small and varying proportions (2 to 3 percent of brewing malt), they introduce considerable variations in colour and flavour to finished beers. Chocolate malt and roasted ungerminated barley are used at a high proportion (25 percent) to make stouts and porters. The use of unmalted cereals has also become common, because they are less expensive sources of starch and can be used to dilute malt colour and flavour, thereby yielding fresher, lighter beers.
Modernization
Modern
maltings can produce malt in four to five days, and technological improvements
give precise control over temperature, humidity, and use of heat. Tower
maltings have been developed with an uppermost floor for steeping and lower
floors for germination and kilning, producing a compact, semicontinuous
operation that is also fully automated.
Mashing
After
kilning, the malt is mixed with water at 62 to 72 °C (144 to 162 °F), and the
enzymatic conversion of starch into fermentable sugar is completed. The aqueous
extract (wort) is then separated from the residual “spent” grain.
Milling
For
efficient extraction with water, malt must be milled. Early milling processes
used stones driven manually or by water or animal power, but modern brewing
uses mechanically driven roller mills. The design of the mill and the gap
between the rolls are important in obtaining the correct reduction in size of
the malt. The object is to retain the husk relatively intact while breaking up
the brittle, modified starch into particles.
Mixing
the mash or mashing
The
milled malt, called grist, is mixed with water, providing conditions in which
starch, other molecules, and enzymes are dissolved and rapid enzyme action
takes place. The solute-rich liquid produced in mashing is called the wort.
Traditionally, mashing may be one of two distinct types. The simplest process,
infusion mashing, uses a well-modified malt, two to three volumes of water per
volume of grist, a single vessel (called a mash tun), and a single temperature
in the range of 62 to 67 °C (144 to 153 °F). With well-modified malt, breakdown
of proteins and glucans has already occurred at the malting stage, and at 65 °C
(149 °F) the starch readily gelatinizes and the amylases become very active.
Less-well-modified malt, however, benefits from a period of mashing at lower
temperatures to permit the breakdown of proteins and glucans. This requires
some form of temperature programming, which is achieved by decoction mashing.
After grist is mashed in at 35 to 40 °C (95 to 105 °F), a proportion is
removed, boiled, and added back. Mashing with two or three of these decoctions
raises the temperature in stages to 65 °C (149 °F). The decoction process,
traditional in lager brewing, uses four to six volumes of water per volume of
grist and requires a second vessel called the mash cooker.
Other
sources of starch that gelatinize at 55 to 65 °C (131 to 149 °F) can be mashed
along with malt. Wheat flour and corn (maize) flakes may be added directly to
the mash, whereas corn grits and rice grits must first be boiled in order to
gelatinize. Their use requires a third vessel, the cereal cooker.
Modern mashing systems use mixed grists and mash mixers, which are efficiently stirred in temperature-programmed mashing vessels. Enzymes of bacterial and fungal origin may be added as aids. Ale and lager are mashed in the same equipment, but they require different temperature programs and grist composition. Modern breweries often practice high-gravity brewing, in which highly concentrated worts are made, fermented, and then diluted, allowing more beer to be brewed on the same equipment.
Modern mashing systems use mixed grists and mash mixers, which are efficiently stirred in temperature-programmed mashing vessels. Enzymes of bacterial and fungal origin may be added as aids. Ale and lager are mashed in the same equipment, but they require different temperature programs and grist composition. Modern breweries often practice high-gravity brewing, in which highly concentrated worts are made, fermented, and then diluted, allowing more beer to be brewed on the same equipment.
Separating
the wort
The
mash tun used in infusion mashing is fitted with a false base containing
precisely machined slots through which the husk, preserved during milling,
cannot pass. The trapped husk thus forms a filter bed that removes solids from
the wort as it is drained, leaving a residue of spent grains. Wort separation
takes 4 to 16 hours. For thorough extraction, the solids are sprayed, or sparged,
with water at 70 °C (160 °F).
The decoction brewer transfers the mash to a separation vessel called the lauter tun, where a shallow filter bed is formed, allowing a more rapid runoff time of about 2.5 hours. Large modern breweries use either lauter tuns or special mash filters to speed up the runoff and conduct 10 or 12 mashes a day. As much as 97 percent of the soluble material is obtained, and 75 percent of this is fermentable. Wort is approximately 10 percent sugar (mainly maltose and maltotriose), and it contains amino acids, salts, vitamins, carbohydrates, and small amounts of protein.
The decoction brewer transfers the mash to a separation vessel called the lauter tun, where a shallow filter bed is formed, allowing a more rapid runoff time of about 2.5 hours. Large modern breweries use either lauter tuns or special mash filters to speed up the runoff and conduct 10 or 12 mashes a day. As much as 97 percent of the soluble material is obtained, and 75 percent of this is fermentable. Wort is approximately 10 percent sugar (mainly maltose and maltotriose), and it contains amino acids, salts, vitamins, carbohydrates, and small amounts of protein.
Boiling
and fermenting
Boiling
After
separation, the wort is transferred to a vessel called the kettle or copper for
boiling, which is necessary to arrest enzyme activity and to obtain the
bitterness value of added hops.
Hops
Several
varieties of the hop (Humulus lupulus) are selected and bred for the bitter and
aromatic qualities that they lend to brewing. The female flowers, or cones,
produce tiny glands that contain the chemicals of value in brewing. Humulones
are the chemical constituents extracted during wort boiling. One fraction of
these, the α-acids, is isomerized by heat to form the related iso-α-acids,
which are responsible for the characteristic bitter flavour of beer.
Traditionally, the dried hop cones are added whole to the boiling wort, but powdered compressed hops are often used because they are more efficiently extracted. In addition, the hop components may be extracted by solvents such as liquid carbon dioxide and added in this form to the wort or, after isomerization, to the finished beer.
Traditionally, the dried hop cones are added whole to the boiling wort, but powdered compressed hops are often used because they are more efficiently extracted. In addition, the hop components may be extracted by solvents such as liquid carbon dioxide and added in this form to the wort or, after isomerization, to the finished beer.
Heating
and cooling
The
kettle boil lasts 60 to 90 minutes, sterilizing the wort, evaporating
undesirable aromas, and precipitating insoluble proteins (known as hot break,
or trub). Trub and spent hops are then removed in a separator where the hop
cones form the filter bed. In modern practice a more rapid whirlpool separator
is also used. This device is a cylindrical vessel into which wort is pumped at
a tangent, the circulating whirlpool movement causing solids to form a cone at
the bottom. Clarified wort is cooled, formerly in shallow troughs or by
trickling down an inclined cooled plate but now in a plate heat exchanger. This
last is an enclosed, hygienic vessel in which hot wort runs along plates while
cold water passes along the other side in the opposite direction. Oxygen is
added at this stage, and the cooled wort passes to fermentation vessels.
Fermentation
In this
most important stage of the brewing process, the simple sugars in wort are
converted to alcohol and carbon dioxide, and green (young) beer is produced.
Fermentation is carried out by yeast, which is added, or pitched, to the wort
at 0.3 kilogram per hectolitre (about 0.4 ounce per gallon), yielding 10,000,000
cells per millilitre of wort.
Yeast
Yeasts
are classified as fungi; those strains used for fermentation are of the genus
Saccharomyces (meaning “sugar fungus”). In brewing it is traditional to refer
to ale yeasts used predominantly in top fermentation as top strains of S.
cerevisiae and to lager yeasts as bottom strains of S. carlsbergensis. Modern
yeast systematics, however, classifies all brewing strains as S. cerevisiae,
and many ales are made by bottom fermentation with what were originally top strains.
Many hundreds of simple organic compounds have been characterized in beer and many more identified, and the majority of these are produced by yeast. The bitter substances of hops, ethyl alcohol, and carbon dioxide have the greatest effects on the senses of taste and smell. Other compounds giving a beer its character include: esters such as isoamyl acetate (banana), ethyl hexanoate (apple), and ethyl acetate (solvent); higher alcohols such as isoamyl alcohol and 2-phenyl ethanol; acids such as octanoic, acetic, isovaleric, butyric malic, and citric; dialkyl sulfides such as dimethyl sulfide; and diketones such as diacetyl. The ester ethyl isovalerate and the aldehyde nonenal contribute to stale and oxidized flavours. The mechanisms of metabolism leading to the formation of these flavouring agents are neither well understood nor easily changed. Until new processes (perhaps genetic engineering) can produce changes in brewer’s yeast, brewers will attach great value to known yeast strains and will maintain selected strains for brewing particular beers.
Many hundreds of simple organic compounds have been characterized in beer and many more identified, and the majority of these are produced by yeast. The bitter substances of hops, ethyl alcohol, and carbon dioxide have the greatest effects on the senses of taste and smell. Other compounds giving a beer its character include: esters such as isoamyl acetate (banana), ethyl hexanoate (apple), and ethyl acetate (solvent); higher alcohols such as isoamyl alcohol and 2-phenyl ethanol; acids such as octanoic, acetic, isovaleric, butyric malic, and citric; dialkyl sulfides such as dimethyl sulfide; and diketones such as diacetyl. The ester ethyl isovalerate and the aldehyde nonenal contribute to stale and oxidized flavours. The mechanisms of metabolism leading to the formation of these flavouring agents are neither well understood nor easily changed. Until new processes (perhaps genetic engineering) can produce changes in brewer’s yeast, brewers will attach great value to known yeast strains and will maintain selected strains for brewing particular beers.
Fermenting
methods
Brewing
is unique among the beverage fermentation industries in that yeast from one
fermentation is used to pitch the next. This means that hygienic conditions and
rigorous quality control are necessary. A high proportion of live cells and
freedom from bacteria and other yeasts are important quality considerations.
Traditional open-topped earthenware fermentation vessels gave way to round wooden vessels and later square copper-lined fermentors, and brewery fermentation systems evolved around the mechanism used to separate yeast from freshly fermented, or green, beer. Top fermentations, in which yeast rises to the surface, require the most elaborate systems, but most brewing operations now use more hygienically operated closed vessels and bottom fermentation. These vessels, erected outside the brewery, are several thousand hectolitres in capacity (1 hectolitre = 26 U.S. gallons = 22 U.K. gallons) and are made of stainless steel. Temperature control is achieved by circulating cold liquid in jackets fitted to the wall of the vessel. Large ale breweries also use this system, removing ale yeast from the bottom of the vessel.
The temperature of the wort at pitching is 15 to 18 °C (59 to 65 °F) for ale and 7 to 12 °C (45 to 54 °F) for lager. As fermentation proceeds, the specific gravity falls as the sugars are metabolized by the yeast. The extent of fermentation is governed by the wort composition and by the amount of fermentable sugar to remain in maturing beer. During fermentation, yeast multiplies five- to eightfold and generates heat. The temperature is allowed to rise until it reaches 20 to 23 °C (68 to 74 °F) for ale and 12 to 17 °C (54 to 63 °F) for lager. At that point the fermentation is cooled to 15 °C (59 °F) for ale and 4 °C (39 °F) for lager, considerably slowing yeast action. Yeast is then removed and the green beer, still containing about 500,000 yeast cells per millilitre, is transferred to a conditioning or maturation vessel, where a secondary fermentation may take place. In traditional brewing, the primary stage of fermentation took seven days for ale and three weeks or more for lager. These times have been shortened to 2 to 4 days and 7 to 10 days by modern practices using more-efficient fermentation vessels.
Traditional open-topped earthenware fermentation vessels gave way to round wooden vessels and later square copper-lined fermentors, and brewery fermentation systems evolved around the mechanism used to separate yeast from freshly fermented, or green, beer. Top fermentations, in which yeast rises to the surface, require the most elaborate systems, but most brewing operations now use more hygienically operated closed vessels and bottom fermentation. These vessels, erected outside the brewery, are several thousand hectolitres in capacity (1 hectolitre = 26 U.S. gallons = 22 U.K. gallons) and are made of stainless steel. Temperature control is achieved by circulating cold liquid in jackets fitted to the wall of the vessel. Large ale breweries also use this system, removing ale yeast from the bottom of the vessel.
The temperature of the wort at pitching is 15 to 18 °C (59 to 65 °F) for ale and 7 to 12 °C (45 to 54 °F) for lager. As fermentation proceeds, the specific gravity falls as the sugars are metabolized by the yeast. The extent of fermentation is governed by the wort composition and by the amount of fermentable sugar to remain in maturing beer. During fermentation, yeast multiplies five- to eightfold and generates heat. The temperature is allowed to rise until it reaches 20 to 23 °C (68 to 74 °F) for ale and 12 to 17 °C (54 to 63 °F) for lager. At that point the fermentation is cooled to 15 °C (59 °F) for ale and 4 °C (39 °F) for lager, considerably slowing yeast action. Yeast is then removed and the green beer, still containing about 500,000 yeast cells per millilitre, is transferred to a conditioning or maturation vessel, where a secondary fermentation may take place. In traditional brewing, the primary stage of fermentation took seven days for ale and three weeks or more for lager. These times have been shortened to 2 to 4 days and 7 to 10 days by modern practices using more-efficient fermentation vessels.
Maturation
and packaging
A slow
secondary fermentation of residual or added sugar (called primings) or, in
lager brewing, the addition of actively fermenting wort (called krausen)
generates carbon dioxide, which is vented and purges the green beer of
undesirable volatile compounds. Continued yeast activity also removes strong
flavouring compounds such as diacetyl. Allowing pressure to build up in the
sealed vessel then increases the level of carbonation, giving the beer its
“condition.” In traditional brewing, large volumes of ale were conditioned in
tanks for seven days at 15 °C (59 °F), whereas lagers were matured at 0 °C (32
°F) for up to three months. These long maturation periods were necessary
because of the precipitation of protein-tannin complexes, which at low
temperature form “chill hazes” that are slow in settling out. Modern practice
speeds up this process by adding excess tannin, clarifying with protein or
tannin adsorbents, or using enzymes to degrade the proteins.
Traditional, or “real,” ales are packaged into casks. Sugar primings, clarifying agents such as isinglass finings, and whole hops are added, and the beer is transferred to the point of sale, where it is carefully vented to the proper level of conditioning before being sold. Some British, Australian, and U.S. microbrewed ales are packaged in bottles together with yeast to make “bottle-conditioned” beer.
Beer produced on a large scale in modern breweries is kept free of oxygen (which ultimately spoils beer), filtered through cellulose or diatomaceous earth to remove all yeast, and packaged at 0 °C (32 °F) under pressure of carbon dioxide. Beer produced by high-gravity brewing is diluted to the desired alcohol concentration immediately prior to packaging with oxygen-free, carbonated water. Most beers packaged in bottles or metal cans are pasteurized in pack by heating to 60 °C (140 °F) for 5 to 20 minutes. Beer is also packaged into metal kegs of 50-litre (in the United States, 15-gallon) capacity after pasteurization at 70 °C (160 °F) for 5 to 20 seconds. Modern packaging machinery is designed to operate hygienically, exclude air, and run at rates of 2,000 cans or bottles per minute.
Traditional, or “real,” ales are packaged into casks. Sugar primings, clarifying agents such as isinglass finings, and whole hops are added, and the beer is transferred to the point of sale, where it is carefully vented to the proper level of conditioning before being sold. Some British, Australian, and U.S. microbrewed ales are packaged in bottles together with yeast to make “bottle-conditioned” beer.
Beer produced on a large scale in modern breweries is kept free of oxygen (which ultimately spoils beer), filtered through cellulose or diatomaceous earth to remove all yeast, and packaged at 0 °C (32 °F) under pressure of carbon dioxide. Beer produced by high-gravity brewing is diluted to the desired alcohol concentration immediately prior to packaging with oxygen-free, carbonated water. Most beers packaged in bottles or metal cans are pasteurized in pack by heating to 60 °C (140 °F) for 5 to 20 minutes. Beer is also packaged into metal kegs of 50-litre (in the United States, 15-gallon) capacity after pasteurization at 70 °C (160 °F) for 5 to 20 seconds. Modern packaging machinery is designed to operate hygienically, exclude air, and run at rates of 2,000 cans or bottles per minute.
Types
of beer
Beverages
similar to beer are produced in Japan (sake, from rice) and Mexico (pulque,
from agave). In much of Africa, malted sorghum, millet, and maize (corn) are
used to produce local beers such as bouza, burukutu, pito, and tshwala. The
Tarahumara of Mexico incorporate the drinking of a maize beer, tesquino, into
important social rituals.
In Europe the properties of the water used for brewing, the types of malt, the brewing practices, and the yeast strains have contributed to traditional distinctions between beers. Early British beers were made from successive extracts of a single batch of brown malt in a top-fermentation process. The first and strongest extract gave the best-quality beer, called strong beer, and a third extract yielded the poorest-quality beer, called small beer. In the 18th century, London brewers departed from this practice and produced porter. Made from a mixture of malt extracts, porter was a strong, dark-coloured, highly hopped beer consumed by the market porters in London. Brewers in Burton upon Trent, using the famous hard waters of that region and pale malts roasted in coke-fired kilns, created pale ales, also called best bitter. Pale ale is less strong, less bitter, paler in colour, and clearer than porter. Mild ales—weaker, darker, and sweeter than bitter—are a common variation; more colour is obtained by special malts, roasted barley, or caramels, less hops are used, and cane sugar is added to impart sweetness and aid maturation. Stouts are stronger versions of mild ale; some, such as milk stouts, contain lactose (milk sugar) as a sweetener. Beers with alcohol content well in excess of 5 percent are produced in the United Kingdom (barley wines), Belgium, and the Netherlands (for example, Trappist beers).
In Europe the properties of the water used for brewing, the types of malt, the brewing practices, and the yeast strains have contributed to traditional distinctions between beers. Early British beers were made from successive extracts of a single batch of brown malt in a top-fermentation process. The first and strongest extract gave the best-quality beer, called strong beer, and a third extract yielded the poorest-quality beer, called small beer. In the 18th century, London brewers departed from this practice and produced porter. Made from a mixture of malt extracts, porter was a strong, dark-coloured, highly hopped beer consumed by the market porters in London. Brewers in Burton upon Trent, using the famous hard waters of that region and pale malts roasted in coke-fired kilns, created pale ales, also called best bitter. Pale ale is less strong, less bitter, paler in colour, and clearer than porter. Mild ales—weaker, darker, and sweeter than bitter—are a common variation; more colour is obtained by special malts, roasted barley, or caramels, less hops are used, and cane sugar is added to impart sweetness and aid maturation. Stouts are stronger versions of mild ale; some, such as milk stouts, contain lactose (milk sugar) as a sweetener. Beers with alcohol content well in excess of 5 percent are produced in the United Kingdom (barley wines), Belgium, and the Netherlands (for example, Trappist beers).
Bottom-fermented
lagers have their origins in continental Europe. Brewers in Plzeň (now in the
Czech Republic) used local soft waters to produce the famous Pilsner beer,
which became the standard for highly hopped, pale-coloured, dry lagers.
Dortmunder is a pale lager of Germany, and Munich has become associated with
dark, strong, slightly sweet beers with less hop character. The dark colour
comes from highly roasted malt, and other characteristic flavours arise during
the decoction mashing process. Bock is an even stronger, heavier Munich-type
beer that is brewed in winter for consumption in the spring. Märzbier (“March
beer”) is a lighter brew produced in the spring. While all German lagers are
made with malted barley, a special brew called weiss beer (Weissbier; “white
beer”) is made from malted wheat. In other countries such as Denmark, the
Netherlands, and the United States, other cereals are used in lighter-coloured
lager beers.
Lambic
and gueuze beers are produced mainly in Belgium. The wort is made from malted
barley, unmalted wheat, and aged hops. The fermentation process is allowed to
proceed from the microflora present in the raw materials (a “spontaneous”
fermentation). Different bacteria (especially lactic acid bacteria) and yeasts
ferment the wort, which is high in lactic acid content. Lambic beer is the cask
product sold locally. Gueuze is bottled and refermented lambic beer. Filtered
gueuze, the most popular product, is a bottled blend of lambic and gueuze. A
cask product made in a similar manner is thought to have been consumed by
miners in the United States during the California Gold Rush.
The strength of beer may be measured by the percentage by volume of ethyl alcohol. Strong beers are in excess of 4 percent, the so-called barley wines 8 to 10 percent. Diet beers or light beers are fully fermented, low-carbohydrate beers in which enzymes are used to convert normally unfermentable (and high-calorie) carbohydrates to fermentable form. In low-alcohol beers (0.5 to 2.0 percent alcohol) and “alcohol-free” beers (less than 0.1 percent alcohol), alcohol is removed after fermentation by low-temperature vacuum evaporation or by membrane filtration. Other low-alcohol products may be produced from worts of low fermentability, using yeasts that cannot ferment maltose, or by mixing yeast separated from a normal fermentation with weak wort at a low temperature for a short time.
The 20th century saw the erosion of traditional distinctions based on place of manufacture, raw materials, and brewing methods. This has caused a reaction among a small body of consumers. In Britain it has encouraged support for smaller, traditional ale breweries. In the United States a growing number of “microbreweries” brew beers with more flavour and colour.
The strength of beer may be measured by the percentage by volume of ethyl alcohol. Strong beers are in excess of 4 percent, the so-called barley wines 8 to 10 percent. Diet beers or light beers are fully fermented, low-carbohydrate beers in which enzymes are used to convert normally unfermentable (and high-calorie) carbohydrates to fermentable form. In low-alcohol beers (0.5 to 2.0 percent alcohol) and “alcohol-free” beers (less than 0.1 percent alcohol), alcohol is removed after fermentation by low-temperature vacuum evaporation or by membrane filtration. Other low-alcohol products may be produced from worts of low fermentability, using yeasts that cannot ferment maltose, or by mixing yeast separated from a normal fermentation with weak wort at a low temperature for a short time.
The 20th century saw the erosion of traditional distinctions based on place of manufacture, raw materials, and brewing methods. This has caused a reaction among a small body of consumers. In Britain it has encouraged support for smaller, traditional ale breweries. In the United States a growing number of “microbreweries” brew beers with more flavour and colour.
BEER
MAKING CHART
Difference
between ale and lager
1. Ales
are made with top fermenting yeast called as Saccharomyces Cerevisiae
Lagers are prepared by bottom fermenting yeast yeast called Saccharomyces Uvarum
Lagers are prepared by bottom fermenting yeast yeast called Saccharomyces Uvarum
2. Top
fermenting yeast produce esters which affect the flavor of the beer
The bottom fermenting yeast does not add much in the way of
the flavor of the beer.
The bottom fermenting yeast does not add much in the way of
the flavor of the beer.
3. Ale
ferments at a higher temperature generally at about 75° F or 23°C.
Lager ferments at a relatively lower temp. at
around 46 – 59° F or 7° — 15°C.
Lager ferments at a relatively lower temp. at
around 46 – 59° F or 7° — 15°C.
4. Ale
are fermented by a quick brew cycle which last for around 7 days.
Lager beers are fermented by a brew cycle
which lasts for months.
Lager beers are fermented by a brew cycle
which lasts for months.
5. Ale
recipes often contain a higher amount of hops, malt and roasted malts, hence
they typically have a more prominent malty taste and bitterness
Lagers normally contains moderate amount of
hops and malted barley to give a balanced
taste.
Lagers normally contains moderate amount of
hops and malted barley to give a balanced
taste.
6.
Served not too cool, usually 50-55 degrees F, 10-14 degrees C, sometimes called
“cellar temperature.
Lagers are served cold, usually 40-45 degrees F, 4-7°C
Lagers are served cold, usually 40-45 degrees F, 4-7°C
7. Ales
are normally mashed by infusion method
Lagers are mashed by decoction method.
Lagers are mashed by decoction method.
8. Ale
production involves the use of fully modified Malt. Lager production involves
the use of less or partially modified malt.
Malt.
Malt.
Ales are
conditioned as cask or bottle conditioned For about 7 days.
Lager is conditioned in refrigerated tanks for about 3 months.
“
Lager is conditioned in refrigerated tanks for about 3 months.
“
