DIPLOMA IN BREWING
Module 1
Materials and Wort
Barley & Malt (p.1)
Adjuncts, Enzymes, Water & Hops (p.14)
Malt Handling & Brewhouse Processes (p.25)
Cleaning, Hygiene and Effluent (p.39)
,BARLEY & MALT
Brief Summary: Structure and composition of barley grains
There are two species of barley used for brewing, Hordeum vulgare (six-rowed barley) and Hordeum distichon
(two-rowed barley). The grain is mostly made up of starch, protein and sucrose; however also contains b-glucan,
phytic acid and phenolic material.
The grain can be divided into six main components.
Component Composition/Function
Husk
• Multi-layered structure that provides the grain with rigidity and protects the embryo
• Aids hydration of the grain whilst hindering dehydration (malting significance)
• Semi-permeable layer which restricts water absorption helping to prevent grain rot
Pericarp • Impervious to CO2 and gibberellic acid
• Selective damage or abrading of the husk and pericarp increases the permeability of the
grain to water
• Two cuticular lipid layers that are permeable to gibberellic acid but prevent the inward or
outward movement of amino acids, sugars and other low molecular weight nutritional
Testa
components of the grain interior
• Surface structures outside the testa usually contain mixed populations of microorganisms
• Consists of cubical respiring cells (starch free)
• Responsible for the synthesis of a range of hydrolytic enzymes from phytic acid and
Aleurone proteins, which are released into the endosperm and degrade and convert the starch during
germination
• Contains minerals and B vitamins, which are yeast growth factors
• Densely packed tissue of non-respiring cells that acts as a store of nutrients
Endosperm • Cells contain type A (large) and type B (small) starch granules embedded in a protein matrix
• Cells also contain small air-filled spaces, the amount of which, determine the difference
between “mealy” and “steely” grains
• Comprised of the axis and scutellum
• The axis contains the first leaves stored in a leaf sheath and rootlet initials stored in a root
sheath
Embryo
• The scutellum is an epithelial layer pressed against the endosperm
• The embryo produces hormones (gibberellins), which are transported to the aleurone to
stimulate production and release of hydrolytic enzymes at the onset of germination
Micropyle • Exists at the base of the grain and is where water is taken up to be distributed across the
embryo when the pericarp is intact
Overview: Barley breeding and selection of brewing varieties
Barley breeding and variety selection has been around for decades and is responsible for producing many of the
barley varieties currently grown for malting. Barley breeding is ongoing around the world and aims at improving
the characteristics of commercial barley varieties. Agronomic qualities such as increased yield, resistance to
mechanical stress (storms, wind, harvesting), disease resistance and growth rate are all important traits when
selecting barley lines along with qualities that increase the potential of the barley to produce high quality malt
such as increased grain size and uniformity, low dormancy, low grain nitrogen content and high extract potential.
The barley plant is self-pollinating and therefore by Mendel’s law will always tend towards homozygous over
generations (identical alleles for each trait). Traditional barley breeding involves the crossing of varieties to
combine traits by pollinating barley plants with the pollen from other varieties. The seed harvested then has to be
recultivated a number of times (usually up to 7 generations) with careful selection of plants to achieve a uniform
homozygous line with the desired characteristics. The crossing of varieties can range from simple crossing of two
varieties to complicated back crossing and mixed crossing of different generations. Barley breeding at this level
requires inherent variability in the breeding population. In the absence of sufficient variability, mutations can be
induced to develop new lines of barley plants with new traits; however, desirable mutations generally come with
other deleterious genetic changes.
1
,The process of developing new lines for acceptance as official new varieties can take over ten years due to the
number of generations required to produce a homozygous line as well as the testing requirements to confirm the
distinctiveness, uniformity and stability of the line (DUS test) and the subsequent malting and brewing trials
before it is accepted by the trade. Artificial growth environments and molecular biology techniques and tools such
as SSLP, RFLP, molecular markers and DNA probes can speed up this process and make it much easier to
identify the successful inheritance of specific traits in the new lines.
Genetic engineering allows greater control over the creation of new lines without the time or trial and error of
cross breeding and induced mutations. Genetic engineering of barley essentially involves transforming the
genome of target cells with either an existing or constructed gene. Transgenic cells can then be identified using
genetic markers, often in the form of a herbicide resistance. Some of the genetically engineered characteristics
that have been researched in barley plants include the production of heat stable enzymes, increased enzyme
production, reduced b-glucan levels and disease resistance. While genetic engineering of barley lines is a reality,
it may still be some time before consumer acceptance allows genetically engineered lines to be grown for
commercial use.
Details: Evaluation of barley for malting (desirable characteristics, sampling, analyses)
Barley at intake must be assessed both visually and using laboratory methods to determine the quality of the
barley and its suitability for malting and brewing. For every truckload of grain only a few hundred grams will be
tested therefore the samples drawn from the truck must be representative of the entire truckload. This is best
achieved by sampling devices such as controlled pneumatic spears that sample a truck’s grain load at different
depths and positions. The samples are then mixed and subdivided for analysis.
Purchasing decisions for grain loads at intake require quick assessments, which will determine if the load is
accepted or rejected and the purchase amount. After intake grain is screened, cleaned and dried. The grain is
then subject to a more thorough laboratory evaluation. The parameters assessed and the appropriate
tests/checks at intake and after intake are:
• Moisture – the moisture content of the grain must be low enough for stability during storage and is therefore
dried to 12% moisture after intake. Grain with moisture levels exceeding the specification (usually around
15%) will incur financial penalty due to the energy and time involved in drying the grain. However, farm
drying, if detected, should result in rejection of the grain load as it will often result in damage to the embryo.
o Determined at intake by visual assessment (for local wetting) and Near Infrared Spectroscopy (NIR)
o Determined after intake by dry weight measurements
• Nitrogen content – The nitrogen content of the grains (mostly in the form of proteins) is important as it is
inversely related to starch content therefore a high protein content means you will get a lower extract.
However, a low protein content may not meet the brewers requirements due to the amino acids and peptides
liberated during malting and mashing being vital yeast nutrients that also influence foam stability. Ideally the
protein content will be 10.5 – 11.5% (w/w).
o Determined at intake by Near Infrared Spectroscopy (NIR) or other automated equipment (eg. LECO)
o Determined after intake by bench methods (eg. Dumas or Kjeldahl methods)
• Mealiness of the grains – The mealiness or steeliness of the grain is related to nitrogen content. Steely
grains have a more densely packed protein matrix in their endosperm cells, while mealy grains have a less
dense protein matrix with more air spaces. Mealy grains are more suitable for malting as they will hydrate
and be modified more rapidly and evenly than steely grains.
o Determined at or after intake by visual assessment
• Variety purity – The purity of the variety of barley is essential so that maltsters can meet the requests of
their customers.
o Determined at intake by visual assessment of grain morphology and checking grain history and
paperwork
o Determined after intake by immuno-electrophoresis or molecular markers (genetic fingerprinting)
• Grain size & distribution – Grain size and distribution are important quality parameters as larger grains
yield proportionately more extract and an uneven size distribution will cause uneven modification of the grain
during malting and will cause increased losses during screening, destoning and milling.
o Determined at intake by grading using slotted screens or sieves (usually with widths of 2.2, 2.5 and
2.8mm)
o Determined after intake by the Thousand Corn Weight (TCW)
2
, • Grain viability – the grains must be alive so that they can germinate during the malting process. If the
overall viability of the grain load is <95% the load should be rejected.
o Determined at intake by staining dissected grains with tetrazolium chloride to determine enzyme activity
o Determined after intake by the Germinative Capacity (GC) test where grains are steeped with hydrogen
peroxide
• Dormancy – The duration of dormancy will determine the storage times required before the grain is suitable
for malting. A type of dormancy known as water sensitivity will also influence the amount of steeping water
required for successful germination
o Determined after intake by the Germinative Energy (GE) test, which determines the germinating
capacity of the grains at the time of testing. The specification is usually around 98%. The water
sensitivity test can also be conducted, which compares germination of the grains in standard and
excess water.
• Pre-harvest sprouting – Sprouted grains will lead to uneven modification during malting as they will be
modified much more rapidly unless they are stored for too long in which case they will die and not germinate
at all.
o Determined by visual assessment (aided by tetrazolium staining)
• Insect infestation – grain must be free of insect infestation.
o Determined at intake by visual assessment
• Bacterial or fungal infection – Bacterial or fungal infections beyond the natural microflora of the grain husk
must be avoided as they can reduce the extract potential of the grain, cause discolouration or off-flavours in
the malt, give rise to polypeptides that initiate gushing in beer, produce potentially toxic mycotoxins or cause
water sensitivity of the grain where the microflora competes with the grain for oxygen during germination
o Determined at intake by visual assessment for discolouration or visible fungal structures (eg. ergot
sclerotia) as well as “nosing” for spoilage aromas
o Determined after intake by microbiological culturing and plating techniques, immunoassays for specific
mycotoxins or microscopic analysis
• Husk Condition – The husk thickness will determine if the grain is suitable for malting (thin husks allow a
more rapid uptake). Also the husks should be intact as they play a vital role in protecting the grain embryo,
hindering dehydration and preventing infection.
o Determined at intake by visual assessment for cracked or damaged husks
o Determined after intake by microscopic analysis of husk thickness
• Extract Potential – The amount of extract able to be produced from the grain can by calculated by the
Bishop equation using the total nitrogen content (% dry weight), TCW and a varietal constant depending on
the malting grade of the barley variety
o Determined after intake by the equation: E = A - 11TN + 0.22TCW (where E x 2.96 = °/kg)
• Chemical residues – The use of pesticides, fungicides, herbicides or plant growth regulators and their
possible residues may need to be avoided depending on the circumstances.
o Determined at intake by checking grain history and paperwork
o Determined after intake by specialised laboratory testing
More comprehensive testing can involve micro-malting, which provides a range of information about the grain
including water uptake, evenness of germination, the most suitable processing conditions and the likely quality of
the final malt. Biochemical assays to assess enzyme activity can also be useful as well as chemical tests to
determine the b-glucan content of the grain.
Brief Summary: Barley intake and storage
Prior to harvesting, the barley in the field must be sufficiently dry (preferable less than 20% moisture); however,
depending on the weather conditions this is not always possible. The barley is harvested and threshed using a
combined harvester and thresher. The farmer must be precise when adjusting the thresher as incorrect
adjustments can either result in significant grain loss or damage to the grains.
After harvesting the grain must be dried down to around 12% moisture for safe storage. If grain is stored above
12% moisture there is a risk of insect attack and microbial infection, particularly mould growth. Above 12%
moisture the rate of respiration of the grain is also sufficient to generate heat and moisture. As more heat is
3
Module 1
Materials and Wort
Barley & Malt (p.1)
Adjuncts, Enzymes, Water & Hops (p.14)
Malt Handling & Brewhouse Processes (p.25)
Cleaning, Hygiene and Effluent (p.39)
,BARLEY & MALT
Brief Summary: Structure and composition of barley grains
There are two species of barley used for brewing, Hordeum vulgare (six-rowed barley) and Hordeum distichon
(two-rowed barley). The grain is mostly made up of starch, protein and sucrose; however also contains b-glucan,
phytic acid and phenolic material.
The grain can be divided into six main components.
Component Composition/Function
Husk
• Multi-layered structure that provides the grain with rigidity and protects the embryo
• Aids hydration of the grain whilst hindering dehydration (malting significance)
• Semi-permeable layer which restricts water absorption helping to prevent grain rot
Pericarp • Impervious to CO2 and gibberellic acid
• Selective damage or abrading of the husk and pericarp increases the permeability of the
grain to water
• Two cuticular lipid layers that are permeable to gibberellic acid but prevent the inward or
outward movement of amino acids, sugars and other low molecular weight nutritional
Testa
components of the grain interior
• Surface structures outside the testa usually contain mixed populations of microorganisms
• Consists of cubical respiring cells (starch free)
• Responsible for the synthesis of a range of hydrolytic enzymes from phytic acid and
Aleurone proteins, which are released into the endosperm and degrade and convert the starch during
germination
• Contains minerals and B vitamins, which are yeast growth factors
• Densely packed tissue of non-respiring cells that acts as a store of nutrients
Endosperm • Cells contain type A (large) and type B (small) starch granules embedded in a protein matrix
• Cells also contain small air-filled spaces, the amount of which, determine the difference
between “mealy” and “steely” grains
• Comprised of the axis and scutellum
• The axis contains the first leaves stored in a leaf sheath and rootlet initials stored in a root
sheath
Embryo
• The scutellum is an epithelial layer pressed against the endosperm
• The embryo produces hormones (gibberellins), which are transported to the aleurone to
stimulate production and release of hydrolytic enzymes at the onset of germination
Micropyle • Exists at the base of the grain and is where water is taken up to be distributed across the
embryo when the pericarp is intact
Overview: Barley breeding and selection of brewing varieties
Barley breeding and variety selection has been around for decades and is responsible for producing many of the
barley varieties currently grown for malting. Barley breeding is ongoing around the world and aims at improving
the characteristics of commercial barley varieties. Agronomic qualities such as increased yield, resistance to
mechanical stress (storms, wind, harvesting), disease resistance and growth rate are all important traits when
selecting barley lines along with qualities that increase the potential of the barley to produce high quality malt
such as increased grain size and uniformity, low dormancy, low grain nitrogen content and high extract potential.
The barley plant is self-pollinating and therefore by Mendel’s law will always tend towards homozygous over
generations (identical alleles for each trait). Traditional barley breeding involves the crossing of varieties to
combine traits by pollinating barley plants with the pollen from other varieties. The seed harvested then has to be
recultivated a number of times (usually up to 7 generations) with careful selection of plants to achieve a uniform
homozygous line with the desired characteristics. The crossing of varieties can range from simple crossing of two
varieties to complicated back crossing and mixed crossing of different generations. Barley breeding at this level
requires inherent variability in the breeding population. In the absence of sufficient variability, mutations can be
induced to develop new lines of barley plants with new traits; however, desirable mutations generally come with
other deleterious genetic changes.
1
,The process of developing new lines for acceptance as official new varieties can take over ten years due to the
number of generations required to produce a homozygous line as well as the testing requirements to confirm the
distinctiveness, uniformity and stability of the line (DUS test) and the subsequent malting and brewing trials
before it is accepted by the trade. Artificial growth environments and molecular biology techniques and tools such
as SSLP, RFLP, molecular markers and DNA probes can speed up this process and make it much easier to
identify the successful inheritance of specific traits in the new lines.
Genetic engineering allows greater control over the creation of new lines without the time or trial and error of
cross breeding and induced mutations. Genetic engineering of barley essentially involves transforming the
genome of target cells with either an existing or constructed gene. Transgenic cells can then be identified using
genetic markers, often in the form of a herbicide resistance. Some of the genetically engineered characteristics
that have been researched in barley plants include the production of heat stable enzymes, increased enzyme
production, reduced b-glucan levels and disease resistance. While genetic engineering of barley lines is a reality,
it may still be some time before consumer acceptance allows genetically engineered lines to be grown for
commercial use.
Details: Evaluation of barley for malting (desirable characteristics, sampling, analyses)
Barley at intake must be assessed both visually and using laboratory methods to determine the quality of the
barley and its suitability for malting and brewing. For every truckload of grain only a few hundred grams will be
tested therefore the samples drawn from the truck must be representative of the entire truckload. This is best
achieved by sampling devices such as controlled pneumatic spears that sample a truck’s grain load at different
depths and positions. The samples are then mixed and subdivided for analysis.
Purchasing decisions for grain loads at intake require quick assessments, which will determine if the load is
accepted or rejected and the purchase amount. After intake grain is screened, cleaned and dried. The grain is
then subject to a more thorough laboratory evaluation. The parameters assessed and the appropriate
tests/checks at intake and after intake are:
• Moisture – the moisture content of the grain must be low enough for stability during storage and is therefore
dried to 12% moisture after intake. Grain with moisture levels exceeding the specification (usually around
15%) will incur financial penalty due to the energy and time involved in drying the grain. However, farm
drying, if detected, should result in rejection of the grain load as it will often result in damage to the embryo.
o Determined at intake by visual assessment (for local wetting) and Near Infrared Spectroscopy (NIR)
o Determined after intake by dry weight measurements
• Nitrogen content – The nitrogen content of the grains (mostly in the form of proteins) is important as it is
inversely related to starch content therefore a high protein content means you will get a lower extract.
However, a low protein content may not meet the brewers requirements due to the amino acids and peptides
liberated during malting and mashing being vital yeast nutrients that also influence foam stability. Ideally the
protein content will be 10.5 – 11.5% (w/w).
o Determined at intake by Near Infrared Spectroscopy (NIR) or other automated equipment (eg. LECO)
o Determined after intake by bench methods (eg. Dumas or Kjeldahl methods)
• Mealiness of the grains – The mealiness or steeliness of the grain is related to nitrogen content. Steely
grains have a more densely packed protein matrix in their endosperm cells, while mealy grains have a less
dense protein matrix with more air spaces. Mealy grains are more suitable for malting as they will hydrate
and be modified more rapidly and evenly than steely grains.
o Determined at or after intake by visual assessment
• Variety purity – The purity of the variety of barley is essential so that maltsters can meet the requests of
their customers.
o Determined at intake by visual assessment of grain morphology and checking grain history and
paperwork
o Determined after intake by immuno-electrophoresis or molecular markers (genetic fingerprinting)
• Grain size & distribution – Grain size and distribution are important quality parameters as larger grains
yield proportionately more extract and an uneven size distribution will cause uneven modification of the grain
during malting and will cause increased losses during screening, destoning and milling.
o Determined at intake by grading using slotted screens or sieves (usually with widths of 2.2, 2.5 and
2.8mm)
o Determined after intake by the Thousand Corn Weight (TCW)
2
, • Grain viability – the grains must be alive so that they can germinate during the malting process. If the
overall viability of the grain load is <95% the load should be rejected.
o Determined at intake by staining dissected grains with tetrazolium chloride to determine enzyme activity
o Determined after intake by the Germinative Capacity (GC) test where grains are steeped with hydrogen
peroxide
• Dormancy – The duration of dormancy will determine the storage times required before the grain is suitable
for malting. A type of dormancy known as water sensitivity will also influence the amount of steeping water
required for successful germination
o Determined after intake by the Germinative Energy (GE) test, which determines the germinating
capacity of the grains at the time of testing. The specification is usually around 98%. The water
sensitivity test can also be conducted, which compares germination of the grains in standard and
excess water.
• Pre-harvest sprouting – Sprouted grains will lead to uneven modification during malting as they will be
modified much more rapidly unless they are stored for too long in which case they will die and not germinate
at all.
o Determined by visual assessment (aided by tetrazolium staining)
• Insect infestation – grain must be free of insect infestation.
o Determined at intake by visual assessment
• Bacterial or fungal infection – Bacterial or fungal infections beyond the natural microflora of the grain husk
must be avoided as they can reduce the extract potential of the grain, cause discolouration or off-flavours in
the malt, give rise to polypeptides that initiate gushing in beer, produce potentially toxic mycotoxins or cause
water sensitivity of the grain where the microflora competes with the grain for oxygen during germination
o Determined at intake by visual assessment for discolouration or visible fungal structures (eg. ergot
sclerotia) as well as “nosing” for spoilage aromas
o Determined after intake by microbiological culturing and plating techniques, immunoassays for specific
mycotoxins or microscopic analysis
• Husk Condition – The husk thickness will determine if the grain is suitable for malting (thin husks allow a
more rapid uptake). Also the husks should be intact as they play a vital role in protecting the grain embryo,
hindering dehydration and preventing infection.
o Determined at intake by visual assessment for cracked or damaged husks
o Determined after intake by microscopic analysis of husk thickness
• Extract Potential – The amount of extract able to be produced from the grain can by calculated by the
Bishop equation using the total nitrogen content (% dry weight), TCW and a varietal constant depending on
the malting grade of the barley variety
o Determined after intake by the equation: E = A - 11TN + 0.22TCW (where E x 2.96 = °/kg)
• Chemical residues – The use of pesticides, fungicides, herbicides or plant growth regulators and their
possible residues may need to be avoided depending on the circumstances.
o Determined at intake by checking grain history and paperwork
o Determined after intake by specialised laboratory testing
More comprehensive testing can involve micro-malting, which provides a range of information about the grain
including water uptake, evenness of germination, the most suitable processing conditions and the likely quality of
the final malt. Biochemical assays to assess enzyme activity can also be useful as well as chemical tests to
determine the b-glucan content of the grain.
Brief Summary: Barley intake and storage
Prior to harvesting, the barley in the field must be sufficiently dry (preferable less than 20% moisture); however,
depending on the weather conditions this is not always possible. The barley is harvested and threshed using a
combined harvester and thresher. The farmer must be precise when adjusting the thresher as incorrect
adjustments can either result in significant grain loss or damage to the grains.
After harvesting the grain must be dried down to around 12% moisture for safe storage. If grain is stored above
12% moisture there is a risk of insect attack and microbial infection, particularly mould growth. Above 12%
moisture the rate of respiration of the grain is also sufficient to generate heat and moisture. As more heat is
3
