Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

DIPLOMA IN BREWING
Module 1
Materials and Wort

Barley & Malt (p
...
14)
Malt Handling & Brewhouse Processes (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 can be divided into six main components
...
Barley breeding is ongoing around the world and aims at improving
the characteristics of commercial barley varieties
...

The barley plant is self-pollinating and therefore by Mendel’s law will always tend towards homozygous over
generations (identical alleles for each trait)
...
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
...
Barley breeding at this level
requires inherent variability in the breeding population
...


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
...

Genetic engineering allows greater control over the creation of new lines without the time or trial and error of
cross breeding and induced mutations
...
Transgenic cells can then be identified using
genetic markers, often in the form of a herbicide 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
...
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
...
The samples are then mixed and subdivided for analysis
...
After intake grain is screened, cleaned and dried
...
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
...
However, farm
drying, if detected, should result in rejection of the grain load as it will often result in damage to the embryo
...

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
...
5 – 11
...

o Determined at intake by Near Infrared Spectroscopy (NIR) or other automated equipment (eg
...
Dumas or Kjeldahl methods)

•

Mealiness of the grains – The mealiness or steeliness of the grain is related to nitrogen content
...
Mealy grains are more suitable for malting as they will hydrate
and be modified more rapidly and evenly than steely grains
...

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
...
2, 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
...

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
...
The specification is usually around 98%
...


•

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 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
...
Also the husks should be intact as they play a vital role in protecting the grain embryo,
hindering dehydration and preventing infection
...
22TCW (where E x 2
...

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
...


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 farmer must be precise when adjusting the thresher as incorrect
adjustments can either result in significant grain loss or damage to the grains
...
If grain is stored above
12% moisture there is a risk of insect attack and microbial infection, particularly mould growth
...
As more heat is

3

generated the rate of respiration increases, therefore action must be taken quickly to remove these “hot spots”
otherwise there is a high risk of microbial growth, pre-germination of the grain or heat damage to the grain
embryo
...
If the
moisture level of the grain is too low the grains can dehydrate and become highly susceptible to damage during
handling
...
The mechanism behind this is largely unknown; however, it is also known that warm
storage after drying will increase this effect
...
Grain is dried either using a
continuous or batch dryer
...
tower dryer) involves continuous movement of the grains
through a drying/aerating and cooling process either by gravity or mechanical conveyors
...
There is a divide in opinions as to whether batch or continuous dryers
are better for grain drying
...
Continuous dryers offer energy savings, shorter
residence times and reduced capital costs
...
The
removal of stones and metal pieces is particularly important as they have the potential to produce a spark, which
can result in dust explosions
...
The barley grains are then graded
to segregate the grains into different size grades
...
Larger grains (1st grade) are used to produce standard malt, smaller grains (2nd grade) are
used for specialty, distillers or blending malts, while unacceptably small grains (3rd grade or “thins”) are used as
animal feed
...
After grading, the grain is stored in pre-cleaned and fumigated silos
...
Grains should be stored
in batches based on variety, grade, quality and dormancy (determined by laboratory testing)
...
” There are three stages: steeping, germination and
kilning
...
Hydration and respiration are
the two key physical/biochemical processes involved in steeping for the initiation of enzymatic activity through
grain germination
...
The water then migrates from the embryo
through the scutellum to the aleurone layer and finally to the endosperm
...
At 30-33% moisture, germination is initiated and as
the grain reaches critical moisture of 42-47% the moisture content is sufficient to support the grain
through the germination process and the production, distribution and activation of particular hydrolytic
enzymes (eg
...


•

Even hydration of the grain is critical to achieve even modification of the endosperm during
germination
...


•

There is no internal capillary action in the barley grain, so it must be fully immersed for complete
hydration
...


•

Over-hydration above 50% moisture will cause the grain to drown
...
Respiration occurs slowly at
first but the heat produced will cause it to increase rapidly
...

If respiration is allowed to increase beyond desirable levels then the grain will hydrate rapidly and
unevenly producing non-homogenous, unevenly modified malt
...
Combined steep/germination vessels (SGV’s) and
steep/germination/kilning vessels (SGKV’s) are available
...
Most steep vessels are equipped to bubble air through the grain
slurry, which has the added benefit of providing oxygen for respiration
...
Some conical vessels are
designed with central circulation or a circulation pump and loop to keep the grain slurry moving
...
During the steep stages, husk and
grain constituents, including sugars and amino acids, leach into the steep liquor
...
mycotoxins), inhibitive of
grain germination or deleterious to malt quality (flavour taints, gushing initiators etc)
...
Both CO2 and ethanol at sufficient levels will inhibit grain germination
...
This process:

•
•
•
•
•

Removes dust, dirt and leached grain components, which are suspended in the steep liquor
Removes microorganisms suspended in the steep liquor
Removes metabolites produced by the grain or microbial populations
Discharges excess heat allowing greater temperature control, and
Replenishes oxygen

The regime of steeps and air rests is dictated by laboratory testing of the grain, data collected from previous
batches and economic factors such as efficiency and water usage
...
These controls in
combination with monitoring the temperature and moisture content of the grain are important to:

•
•
•
•
•
•

Ensure respiration and hydration are occurring at the desired levels,
Prevent dehydration of the grain,
Prevent heat damage to the grain embryo,
Prevent excessive rootlet growth and subsequent malting losses,
Prevent the inhibition of proteases and other enzymes, and
Control the growth of microbial populations
...
Sterilants or populations of harmless
microorganisms may be added to control the populations of damaging microorganisms
...
Hydrogen peroxide, lime, sodium hydroxide and mineral acids may
be used to overcome dormancy to ensure consistent germination of all the grains
...
Similarly, steep liquor in general must be of potable quality and free of taints
otherwise the impurities will potentially be passed on through the malt to the wort
...
It also allows more effective utilisation of exogenous gibberellic acid (GA) if applied to reduce
malting time and produce a more complete modification of the endosperm
...


Germination
The end of steeping and the start of germination are signalled by chitting of the grain where a small white chit
appears as the rootlet sheath emerges from the grain
...
The grain is therefore transferred to germination chambers, which are designed to control grain
temperature, maintain grain moisture and supply sufficient oxygen to the grain
...
The respiring grain produces heat and therefore must be cooled to a suitable
temperature (15-20°C) for protease activity to occur at sufficient levels without reducing the rate of endosperm
modification too much
...
The grain bed is turned, raked or “lightened” at
regular intervals to provide easy passage for the air and break up any preferential air streams through the bed
...

The grain moisture during germination will also influence the rate of endosperm modification
...
The moisture level of the grain cannot be
replenished without further steeps and therefore the moisture must be maintained as best as possible by
humidifying the circulated air up to 100% relative humidity and spraying the grain bed to prevent dehydration
where necessary
...
The benefits and limitations of these
systems are covered in Table 1
...
Benefits/limitations of different germination systems
System

Benefits

Limitations

Floors
requirement

Simple, uniform well-modified malt,

Costly to build, high labour

reduced maintenance, low depreciation
Saladin Box
inertia

Cheap to run, wet casting, flexible

Difficult to clean, high thermal

Wanderhaufen
inflexible, mixing

Easy automation, wet casting

High

Drums

Low labour, easy water spraying

High maintenance costs

Towers
inertia

Low ground area, good heat recovery,

High capital cost, high thermal

maintenance

costs,

easy grain transfer
GKV’s
flexibility

Cost effective, reduced transfers

6

High

capital

cost,

reduced

Physiological & Biochemical Changes
During germination the grain embryo produces gibberellins (plant growth hormones), the most significant to
malting being gibberellic acid (GA), which is produced within the first two days of embryo growth
...
These hydrolytic enzymes are
transported to the endosperm where they degrade or modify the endosperm cell structures to provide available
nutrition for germination and growth of the grain
...
b-amylase), which pre-exist in the endosperm as zymogens
...
Degradation of the Endosperm Cell Walls

•

Cell wall degradation is necessary for other hydrolytic enzymes to access the protein matrix and starch
granules inside
...


•

The glucanases are denatured during kilning, while the carboxypeptidases can survive kilning (with
reduced activity) to release any remaining b-glucan during mashing

•

Remaining b-glucan in the malt will lead to viscous wort, which will retard wort separation, leave sticky
spent grain, reduce filtration efficiency and lead to colloidal instability and haze formation
...
Proteolysis of Endosperm Cell Matrix

•

Proteolysis is stimulated by high moisture levels and lower temperatures and is necessary to expose the
starch granules of the endosperm cells

•
•

Steely endosperms with a densely packed protein matrix hinder hydration and enzyme distribution

•

Endoproteases cleave internal protein bonds releasing polypeptides while exoproteases cleave the
polypeptides at the terminal ends to release small peptides and amino acids

•
•

Carboxypeptidases cleave amino acids from the carboxyl end of produced peptides

•

If insufficient proteolysis occurs during germination then the malt will yield reduced extract (starch
granules left unexposed), supply reduced FAN (problematic fermentations) and lead to colloidal instability
and haze formation in the beer

•

Excessive proteolysis can lead to increased malt colour (maillard reactions of liberated amino acids
during kilning) and the degradation of essential foam forming polypeptides
...
Liquefaction & Saccharification of Endosperm Starch Granules

•

The degradation of the endosperm starch is limited during malting to preserve extract potential; however,
approximately 10% is generally hydrolysed to provide nutrition for the germinating embryo

•
•

a-amylase synthesised in the aleurone breaks the starch down to smaller polymers (liquefaction)

•

Limit dextrinase degrades liberated dextrins to glucose and a-glucosidase converts maltose molecules to
glucose for the embryo to utilise

•

During kilning limit dextrinase and a-glucosidase are denatured while a proportion of a-amylase and bamylase survive the kilning process to continue the degradation of the endosperm starch during mashing

b-amylase activated in the endosperm cleaves individual glucose molecules from these polymers
(saccharification)

The above modification of the grain can be monitored by the soluble nitrogen ration (SNR) or more simply by
assessing the friability of the malt, both of which are a consequence of the degradation of the endosperm cell

7

walls and protein matrix
...

Enriching circulated air with CO2 will have a similar effect
...
During germination the rootlet tuft increases in length from the base the grain whilst the
acrospire grows along the dorsal side of the grain underneath the husk
...
Therefore, the increased
germination time required to achieve a homogenous and complete modification of the endosperm will result in
increased malting loss due to respiration of the germinating grain and the depletion of endosperm nutrients as
the rootlet tuft and acrospire grow
...
The application of gibberellic acid will
accelerate endosperm modification ahead of embryo growth by triggering earlier and enhanced enzyme
production
...
Abrasion
(prior to steeping) is often utilised in conjunction with exogenous gibberellic acid, where the pericarp is scarified
at the distal tip of the grain
...

The abrasion process is not widely employed as it produces malt with poor appearance, creates variability
between grains and more heterogenous malts and results in a loss of malt biomass
...

Potassium bromate will help reduce malting loss by inhibiting proteolytic activity and embryo development, which
also overcomes some of the issues with exogenous gibberellic acid
...

For kilning, the malt is loaded onto one or more perforated floors through which heated air is driven upwards
through the grain bed drawing and removing any grain moisture
...
They also
have the capability to turn the grain bed (turners) in order to achieve homogenous drying and avoid stewing and
are mostly indirectly fired as opposed to directly fired where the products of combustion (eg
...
Kilns are commonly either single floor or two-tier kilns
...

1
...
Forced Drying
•

The internal grain moisture diffuses to the surface of the grain and evaporates causing the grain to
shrink
...
At this point the air-off temperature will suddenly rise to meet the air-on temperature, known as
the “breakthrough” or “breakpoint”
...
Curing

•

Temperatures range from 70-225°C depending on the type of malt being produced and last for 2-4 hours
where the grain moisture is reduced to approximately 3-6%
...
The malt is then conveyed to storage silos where it is stored for up to a month for the moisture content
of the malt population to equilibrate and until the husk becomes pliable again so it won’t shatter during milling
The exact parameters used in the kilning regime will determine the type of malt produced, specifically the level of
enzyme activity and the colour, flavour and aroma of the malt
...
Melanoidins are also soluble
pigments, which contribute amber and reddish-brown colours to beer
...

Kilning temperatures will also influence the levels of dimethyl sulphide (DMS), a significant flavour compound, in
the malt and produced beer
...
DMS is quite volatile and considerable
amounts are driven off during kilning; however, any that remains can be oxidised to dimethyl sulphoxide (DMSO)
...
Increased temperatures during kilning
will ensure that more SMM is converted to DMS and that more of the DMS is driven off by evaporation
...
Indirect kiln firing, low NOx burners and the
burning of elemental sulphur in the kiln all help overcome the problem of nitrosoamines
...
The selection and
breeding of different barley varieties over its years as a cultivated crop has caused the dormancy trait to be
increased beyond what is natural since some level of dormancy is desirable to avoid pre-germination
...

In addition to the variety of barley, some growing conditions during ripening, such as cool, damp weather, will
induce dormancy
...

There are different types of dormancy:
• Innate dormancy due to a genetic or physiological cause
• Enforced dormancy due to unfavourable external conditions
• Induced dormancy due to lasting effects after unfavourable external conditions are removed, and
• Harvest dormancy where germination remains unchanged but the "maltability" of the grain improves with
storage
...


9

Brief Notes: Water sensitivity
Water sensitivity can occur during steeping when husk and grain constituents leach into the steep liquor
...
Water sensitive barley will have an impaired ability to respire or develop and therefore will
germinate unevenly producing poor quality malt
...
The use of sterilants in the steep water is another possibility but
not commonly employed due to financial costs and concerns regarding residues remaining on the grain
...
Water sensitivity is expressed as the difference between germination in 4ml and 8ml as a percentage of
the germination in 4ml
...


germination (4ml) – germination (8ml)
germination (4ml)

x

100

Brief Notes: Malt Types (including specialty malts)
Specialty malts range from light coloured white malts through to charred black or chocolate malts
...
Kilning is the major variation when producing specialty malts; however, the
choice of barley or cereal and the steeping and germination process will also play an important role in
differentiating some malt types
...

Steeping/Germination: Wheat has no husk and therefore hydrates quicker during steeping to generate higher
extract values
...

Kilning: N/A
Malt composition: Wheat contains more protein than barley giving a fuller mouth-feel and enhanced foam
stability
...

Enzyme Activity: N/A
Colour: Very light (2°EBC)
Flavour/Aroma: Altered flavour characteristics from barley malts

Lager / Pilsner Malts
Barley: Plump two-rowed barley with relatively high nitrogen levels
Steeping/Germination: Steeped to a moisture content of around 43% followed by a long cool germination
(below 17°C) to produce a fully modified malt
...

Malt Composition: N/A
Enzyme Activity: High
Colour: Pale
Flavour/Aroma: Weak aroma, remaining SMM/DMS

10

Pale Ale & Mild Malts
Barley: Two-rowed barley with low nitrogen levels
Steeping/Germination: Steeped and germinated at warmer temperatures to generate highly modified malt
Kilning: Kilned and cured at warmer temperatures to remove grassy notes and DMS precursors
...

Malt Composition: N/A
Enzyme Activity: Reduced
Colour: 4 – 6
...
Mild malts also exhibit rich nutty, toffee and caramel flavours
...
Cured at 90°C
Malt Composition: Well modified but not over-modified
Enzyme Activity: Limited
Colour: 5-10°EBC
Flavour/Aroma: Strong nutty, toffee flavour

Munich malts
Barley: High nitrogen levels
Steeping/Germination: Steeped to greater than 45% moisture followed by a long warm germination
Kilning: Initiated with an extended recirculation of warm air to increase the sugars and amino acids available for
maillard reactions
...

Kilning: Loaded wet into roasting drum and heated at 50°C to encourage complete degradation of the starch and
proteins
...

Malt Composition: Starch is liquefied and recrystallised
Enzyme Activity: N/A
Colour: 10-40°EBC; some British caramel malts can be over 300°EBC
...

Flavour/Aroma: Sweet-biscuit, toffee, nutty, malty, caramelised flavours with honey-notes

Amber Malt
Kilning: Pale or mild ale malts are heated in a roasting drum to between 49 and 170°C
...
Impart golden, red hues to beer
...

Kilning: Gradual increase in kilning temperature to a final curing temperature of 215-225°C
...

Kilning: Directly fired in a roasting drum with temperature increased from 80°C to 230°C over first two hours and
reduced to 215°C for final stages
...

Colour: Reddish black (1200-1400°EBC)
Flavour/Aroma: Sharp, dry, acidic, astringent, burnt flavours

Details: Malt quality and specifications
There are a wide range of measurements that can be used to determine the quality of malt and whether it is
suitable for the beer that is to be produced
...
poor extract recovery or impaired wort filtration), while over-modified malts will
have lost potential extract due to grain growth during germination

•

Enzyme activity - Essential measure of malt quality as some enzymes are required at sufficient levels
during mashing to continue the breakdown of grain structure and yield fermentable sugars for fermentation

•

Flavour, colour and aroma – Colour can be easily quantified whereas flavour and aroma are usually
assessed by simple sensory tests and brewing trials; however, headspace gas chromatography can be used
for some defined flavour attributes

Generally, lager malts are produced from barley with higher total nitrogen levels and are germinated and kilned at
lower temperatures than ale malts
...
As a result lager malts are typically less modified
with lower potential extract, lower soluble nitrogen, reduced colour and increased enzyme levels when compared
with ale malts
...
Lager malts will also impart a finer, mild flavour with a tendency for detectable levels of
dimethyl sulphide in the wort, whereas ale malts will give rise to toastier, malty flavours
...

Their relevance will depend on the location, the brewer, the beer to be produced and any adjuncts that are going
to be used
...
Foreign materials can be detected by screenings with air jets
and magnets to isolate stones and metal
...
Sometimes, testing can be carried out on wort produced from the
malt as a measure of quality
...


12

Table 2
...
8mm sieves

Moisture Content

%

2
...
0

1
...
0

Lower moisture content means higher extract
yield and greater stability during storage

Near infrared spectroscopy or dry weight
measurements (oven drying)

Hot Water Extract

%

75 – 80

76 – 83

Measure of the amount of sugar recoverable
from the malt during the brewing process

A hot water mash is prepared, allowed to cool,
filtered and then the dissolved sugars measured

Fermentability

%

86
...
5

86
...
5

Measure of the fermentable malt components

Wort from HWE is fermented & final extract
is calculated as a percentage of the HWE

Total Nitrogen

%

1
...
75

1
...
6

Indication of quality and processing problems
due to high protein levels (eg
...
65 – 1
...
50 – 1
...
5 – 2
...
5

Measure of endosperm cell structure modification

Comparison of hot water extract between a
finely ground and coarse grist

Friability*

%

80

90

Measures the degree of modification (percentage
of the malt millable under gentle conditions)

Friabilimeter

Homogeneity

%

³ 96

³ 96

Measures the percentage of dead or poorly
modified grains present in the finished malt

Friabilimeter

Cold Water Extract*

%

18 – 20

19 – 23

Measure of the amount of sugars broken down &
released during malting (degree of modification)

Preparing a mash in 20°C alkaline water and
measuring the dissolved sugars

°Lintner

60 – 90

35 – 50

Strength of amylase enzymes for mashing

The time required to solubilise all starch in an incubated
sample is measured

Dextrinising Units

DU

25 – 50

20 – 40

a-amylase activity for mashing

enzyme assay kits

b-glucanase levels

-

-

-

b-glucanase enzymes can continue to degrade
remaining b-glucan during mashing

Monitoring the decrease in viscosity of a b-glucan
solution after some malt extract is added

b-glucan*

-

-

-

Measure of residual b-glucan that can cause
haze & processing problems (viscous wort)

Glucose levels are monitored after the addition of
glucanase enzymes

Diastatic Power

Colour

°EBC

2
...
0

4
...
0

Malt colour will have a large (but not absolute)
impact on wort colour

Absorbance at 430nm (multiplied by 25)

SMM/DMS

ppm

8

0

DMS can be a desirable or undesirable flavour
contributor depending on the style of beer

Gas Chromatography

* Degree of modification measurement

13

ADJUNCTS, ENZYMES, WATER & HOPS
Details: Brewhouse adjuncts
An adjunct is usually defined as “any carbohydrate source other than malted barley that contributes sugars to the
wort”
...

Solid adjuncts are manufactured from cereal grains such as barley, wheat, maize, rice, sorghum, oats and rye
...
Starch
granules from maize, rice and sorghum and some of the smaller starch granules of barley have higher
gelatinisation temperatures than those achievable during mashing due to the denaturation temperatures of malt
amylolytic enzymes
...
If raw cereal adjuncts are to be used they are usually put through
rollers to produce coarse grits of endosperm or milled to produce fine flours
...
They only need to dissolve in the wort or beer and therefore their use is much
more simple and reliable than solid adjuncts
...
Current technology means that hydrolysed starch syrups
can be produced with virtually any carbohydrate profile desired
...
Malt extracts are concentrated syrups of wort, which
can be prepared from any range of grist components to achieve the required specifications
...

Solid adjuncts rely on malt or commercial enzymes to convert their starch into available extract
...

Similarly, the use of high volumes of flour adjuncts can cause set mashes where they become too thick to allow
enzyme mixing and conversion of the starch is impaired
...
Therefore, the use of some cereal adjuncts may
need to be accompanied by the use of commercial enzymes such as b-glucanases
...
Some cereal adjuncts
containing increased levels of non-fermentable carbohydrates will also enhance mouthfeel of the fermented beer
...
Adjuncts from different cereals will have varying influences on
foam stability, for example wheat adjuncts are rich in glycoproteins & peptides that improve foam stability, while
maize adjuncts are rich in foam-negative lipids and deficient in nitrogen
...
Low nitrogen levels will decrease foam
stability, decrease free amino nitrogen (for yeast performance) and decrease the ester formation (due to an
increased carbon to nitrogen ratio); however, the low nitrogen levels will also increase beer stability by diluting
the proteins and polypeptides involved in the formation of chill and permanent hazes
...
Liquid adjuncts will also improve brewhouse capacity by allowing faster lauter
run-off, shorter brewing cycles and reduced raw material storage
...
They can also be utilised as primings in the production of bottle or
cask conditioned ales The main implication with these syrups is that they are relatively flavour neutral and
deficient in nitrogen
...
The brewer will also encounter critical levels of adjunct syrups
where the uptake of other sugars by the yeast is suppressed causing stuck or hanging fermentations
...

Solid adjuncts can be dangerous to store due to the risk of dust explosions, particularly in the case of flours,
which also require pneumatic conveyors and can cause issues by blocking vessel outlets
...
The syrups must also be stored at sufficient concentration to inhibit microbial infection and as such
condensation must be avoided
...
Commercial enzymes
are used in brewing to adjust wort and beer sugar spectrums, increase extract utilisation, clarification purposes,
or to compensate for enzyme deficiencies as a result of the use of high levels of adjuncts, the use of malts with
low enzyme activity or the use of unfavourable brewing conditions for malt enzymes
...

The manufacture of commercial enzymes mostly involves microbial cultures that naturally, or through genetic
manipulation, produce large amounts of the target enzyme
...
It is critical
that enzyme preparations are stable, consistent and free of material contaminants, enzyme contaminants and
microbial hazards (viable organisms, spores and mycotoxins)
...

Examples of commercial enzymes utilised by brewers include:
• Heat stable a-amylase for degradation of adjunct starch during pre-cooking
• b-amylase for increased saccharification and dextrin degradation to speed up mashing and increase wort
fermentability
• Amyloglucosidase for increased saccharification and dextrin degradation during mashing to increase wort
fermentability or as an alternative to priming sugar
• b-glucanases for degradation of b-glucan during mashing to reduce wort viscosity and protect against wort
separation difficulties
• Glucose oxidase to scavenge oxygen during mashing to protect from staling reactions
• Proteolytic enzymes (papain, bromelain, ficin etc) for the non-specific degradation of polypeptides to reduce
protein-polyphenol haze potential
• a-acetolactate decarboxylase, which when added to cooled wort will breakdown the diacetyl precursor aacetolactate to speed up diacetyl reduction times during fermentation

Summary: Water hardness
Water hardness is a property of water, which causes difficulty in forming soap lather
...

The effect of water hardness on wort pH adjustment depends on the degree and type of water hardness that is
present
...
Although calcium and magnesium bicarbonates are precipitated during boiling, alkaline
worts during mashing and lautering, as a result of temporary hardness, are detrimental to brewing resulting in:
•

Poor saccharification and reduced extract

•

Poor wort separation

•

Dark worts

•

Poor biological stability

•

Poor protein precipitation, and

•

Astringent beer due to increased polyphenol extraction

Permanent hardness is caused by chlorides or sulphates of calcium and magnesium
...
Permanent hardness is not
removed by boiling and the resulting reduction in pH can be beneficial by:
•

Increasing wort fermentability

•

Improving extract recovery

•

Increasing wort free amino nitrogen

•

Increasing run-off rates, and

•

Reducing the extraction of polyphenols and silica compounds

15

Permanent hardness does have some drawbacks, particularly reduced a-acid isomerization and therefore poor
hop utilisation, and the presence of magnesium salts will contribute a sour, slightly bitter taste to beer and if
present at sufficient concentrations can cause flatulence and induce laxative effects
...
The hardness of water is
measured as total hardness, calcium hardness, magnesium hardness or total alkalinity, all of which are
expressed as mg of CaCO3
...
Temporary hardness can
be removed by simply boiling the water and removing the carbonate precipitate
...
Water hardness can also be treated with sulphuric, hydrochloric
and phosphoric acids, to remove carbonates
...


Details: Composition of brewing liquor and significance in brewing
The composition of brewing water, particularly brewing liquor, dilution water and rinse water, is a critical
determinant of the character, quality and safety of the beer produced and can have effect in three main areas, (i)
microbiological composition, (ii) organic compounds, and (iii) inorganic ion and salt composition
...

The boiling of wort in the kettle should kill most viable microorganisms, with the exception of some thermotolerant
or sporulating bacteria
...
Dilution water must be particularly sterile and usually receives a more reliable sterilisation process
than brewing liquor
...
trihalomethanes,
chlorophenols)
...
Traditionally, different brewing regions were renowned for producing their own
distinct beers because of the unique inorganic ion and salt composition of their water supply
...

The key inorganic components of brewing liquor are: calcium, magnesium, sodium, potassium, iron, zinc, copper,
manganese, carbonates, bicarbonates, chloride, sulphate, nitrite, nitrate and ammonium
...

Permanent water hardness as determined by the presence of chlorides or sulphates of calcium and magnesium
is responsible for reducing the pH of wort throughout mashing, boiling and fermentation where the inorganic ions
and salts react with a range of buffering compounds such as phosphates, organic acids, phytates and
polypeptides, which are precipitated out of solution and hydrogen ions are released
...
The reduction in pH is beneficial by:
•

Increasing wort fermentability

•

Improving extract recovery

•

Increasing wort free amino nitrogen

•

Increasing run-off rates, and

•

Reducing the extraction of polyphenols and silica compounds

The reduction in pH has one main drawback, which is the reduced isomerization of hop a-acids
...
They
also form scale on heating surfaces and can reduce heat transfer efficiencies
...


16

•

Colour formation
Calcium will restrict colour formation during boiling
Nitrite will react with polyphenols to give beer a reddish tinge

•

Yeast growth & function
...


•

Direct flavour contributions
Iron, copper and magnesium can give metallic, rusty or astringent flavour taints
...

Sodium and chloride will increase palate fullness
Sodium, potassium and magnesium can impart sour or salty characters

•

Health implications
Nitrate can form carcinogenic nitrosamines in wort and beer
Magnesium and potassium have the ability to cause flatulence and at elevated levels can induce
laxative effects
Heavy metals can cause serious adverse health effects

•

Indication of water contamination
Ammonium indicates contamination with decomposing organic matter
Nitrite indicates contamination due to pollution
Nitrate indicates contamination with agricultural chemicals
...
In brewing, it is crucial that water used
as brewing liquor, high gravity dilution water, package rinse water and CIP final rinse water must be of potable
quality
...
Water used in brewing post-boiling (dilution water, package rinse water and CIP final rinse water)
must be free of viable microorganisms, otherwise flavour, haze and health and safety issues may be
encountered
...


•

Taste & Odour – water must be free of detectable flavour taints (eg
...


•

pH – water should be of neutral pH or slightly acidic since low pH in the mash and wort will increase wort
fermentability, improve extract recovery, increase free amino nitrogen, increase run-off rates and reduce
extraction of polyphenol and silica compounds
...
There are a number of sterilisation treatments available for

17

brewing water as listed in Table 1
...
Removing the dissolved oxygen from dilution water involves one of two (or a
combination of both) deaeration techniques, (i) heating the water to drive off oxygen (possibly under vacuum), or
(ii) sparging the water with an inert gas such as carbon dioxide or nitrogen
...
Boiling the water for at least 30 minutes
will remove temporary hardness by breaking calcium and magnesium bicarbonates down into insoluble
carbonates
...
The addition of acids such as sulphuric, hydrochloric and phosphoric will
precipitate any carbonate and calcium
...

There are a number of other methods, which will not only treat water hardness but also alter the inorganic ion
and salt composition of the water
...
The distillate will however, still contain any volatile impurities including
organics that are evaporated with the water
...
The nature of
the electrolyte or resin will determine what ions are exchanged and can include sodium ion exchange resin for
the removal of calcium and magnesium, hydrogen ion exchange for de-mineralisation, anion exchange resin for
removing sulphate, carbonates and chlorides and amphoteric exchange resins that are able to exchange cations
and anions simultaneously
...
The advantages and disadvantages of ion exchange and reverse osmosis
are compared in Table 2
...

Carbon filtration through a porous bed of activated carbon will adsorb organic compounds (eg
...

However, carbon filtration is generally ineffective at removing most minerals, salts and dissolved inorganic
compounds
...
Carbon filters also require regular steam sterilisation to prevent the growth of
microorganisms
...
Methods for microbiological treatment of brewing water
Treatment

Antimicrobial
Agent

Mode of
Action

Residual
Activity

Cost

Advantages

Disadvantages

Chlorination

Hypochlorous acid

Unconfirmed

Yes

Low

• Simplicity

• Chlorine off-taste requiring carbon filtration
• Ineffective against chlorine resistant microorganisms
• Risk of the formation of haloforms (eg
...
2 – 0
...
The advantages and disadvantages of ion exchange and reverse osmosis systems for brewing water treatment
System

Advantages

Disadvantages

Ion Exchange

• Resins can exhibit preferential binding to achieve specific ionic compositions
• Low energy input
• Resin can be regenerated

• May leave elevated levels of undesirable ions (eg
...

Hop crops require nitrogen rich fertilizers and spraying hops with pesticides and herbicides is critical to prevent
irreparable damage from pests, disease and competing weeds
...
The lupulin glands (visible as
a yellow/golden dust) of the hop cone provide all the bittering and aroma compounds utilised in brewing
...

After ripening, the hops should be harvested in 10 days to prevent over-ripening of the cones, which leaves them
vulnerable to shattering during harvesting and handling
...
The bines of the plants are cut down and transported to a picking machine, which strips the
cones from the bine
...
The hops are then dried from
around 80% moisture to 10% moisture in large kilns to prevent deterioration during storage
...

The oxidation of bittering varieties is undesirable as oxidation of a-acids removes their ability to isomerise to the
bittering form
...
However, for aromatic
varieties some oxidation can be desirable as some oxidation products of the essential oil are thought to be
important in beer flavour
...
Therefore, male hop plants in the vicinity of the breeding
crop must be destroyed to prevent unwanted natural pollination
...
The crossing of varieties can range from simple crossing of two varieties to
complicated back crossing and mixed crossing of different generations
...


Summary: Hop pests and diseases
Hop varieties vary in their susceptibility to insects and diseases (including both fungal and viral attack), some of
which are specific to hops
...
The main causes of damage to
hop crops are the Damson Hop Aphid, Red Spider Mite, Powdery & Downy Mildew, Verticillium wilt and viruses
such as hop mosaic, hop latent and necrotic ringspot
...
Therefore the
use of resistant hop varieties and biological control are advantageous where effective
...
Can be effectively controlled using biological control
methods
...
Exhibits some resistance to pesticides
...
Best controlled with fungicides prior to flowering
...
Vegetative growth and development of hop cones is seriously affected
...

Verticillium Wilt – Can infect plants through the rootstocks causing serious losses
...

Viruses – Can affect the number of shoots, leaves and cones produced, while some (eg
...
Their control can be difficult and is best achieved by careful selection of
uninfected plants to prevent accumulation of infections
...
Hop varieties can be divided into two
categories, (i) bittering hops, which are high in a-acids, and (ii) aroma hops, which have high proportions of
essential oils that contribute the hoppy aroma
...
Pride of Ringwood and US Cluster are examples of bittering varieties, while Hersbrucker and
Saaz are examples of aroma varieties
...
As such, selection criteria for hops extend beyond simply the levels of a-acids and essential oils
...
The most important contribution of hop compounds to beer is in
terms of flavour, with isomerised hop resins (a- and b- acids) imparting bitterness, while essential oils contribute
to the hoppy aroma of beer
...
The proteins and
polyphenols from hops will contribute to beer haze, while the lipids will reduce foam stability if they persist in the
beer
...
Soft resins are the most important for brewing and
consist of a-acids (humulones) and b-acids (lupulones), both groups being comprised of 6 different isomers
...
This occurs during wort boiling; however, pre-isomerised hop extracts are available, which can provide
bitterness when added after boiling
...
The remaining a- and b-acids
are precipitated upon cooling and contribute to the cold break, which needs to be removed during clarification
and filtration
...

The iso-a-acids are nine times more bitter than iso-b-acids and are therefore the principal bittering compounds in
beer
...
Isocohumulone is associated with a harsher, more unpleasant bitterness and because of this hop varieties with
<25% cohumulone are generally used in brewing
...
Hydrolysis during
wort boiling will form humulinic acid, which is non-bittering, while reverse isomerization can lead to Anti-iso-aacids, which are reported to be twice as bitter as the normal iso-a-acids
...
Tetrahydroiso-α-acids, for example,
contribute 175% of the bitterness of normal iso-a-acids and impart a softer bitterness character
...

Oxidation Products
The oxidation of a-acids is undesirable in hops as they lose their ability to isomerise to bittering form
...

Therefore, the loss of a- and b-acids due to oxidation isn’t often associated with a discernible loss in bitterness
...
In addition, these acids may then be involved
in the formation of ethyl esters, which contribute a stale hops character to beer
...

Iso-a-acids are also susceptible to photo-oxidation if beer is exposed to sunlight or artificial light
...
3-methyl-2-butene1-thiol can be detected at levels as low as 0
...
1µg/L and 1µg/L
...
The chemically reduced forms of iso-a-acids are resistant to photo-oxidation and
therefore must be used as the sole bittering components of beer to be packaged in clear glass
...

Essential Oil
Hops will contain varying amounts of essential oil depending on the variety and the degree of ripening
...
The proportions of essential oil
components will change over storage, with oxygenated compounds and levels of volatile acids increasing
...
Thiol esters from the essential oil can be intensely flavour contributing

22

sulphury notes, which can make a positive contribution to some lagers
...

The common additions for hops are:
(i) Kettle Addition: When present throughout the kettle boil, the hop oil components are almost entirely
vapourised
and removed from the beer
(ii) Late Kettle Addition: Hops added 5-20 minutes before the end of the boil
...
The shape and material of the kettle will impact on the extraction and
vapourisation of the oils
...

(iii) Dry Hopping: Addition of aroma hop varieties (with low resin content) during maturation or cask
conditioning
...

Foam Enhancement
Iso-α-acids can make a positive contribution to foam stability by either, (i) linking small polypeptides with
carbohydrates or melanoidins to form foam-positive compounds, or (ii) forming hydrogen bonds with the
hydrophobic groups on foam-positive proteins to produce a thicker, more stable hydrophobic layer, which can be
further stabilised by cross-linking from bivalent metal ions such as Mg 2+
...
Some hop compounds can also be foam inhibitory,
particularly lipids derived from whole hops or hop pellets
...
Iso-humulone complexes with metal ions (such as nickel or tin), isomerised extracts and particularly
dehydrated humulinic acid can all trigger gushing
...

Antibacterial Properties
Iso-a-acids have antibacterial properties against gram-positive bacteria, including lactic acid bacteria; however,
the reduced forms of iso-a-acids have been reported to be less effective at suppressing lactic acid bacteria
...
Hop resins (a- and b-acids) are closely related to
polyphenols and can potentially be involved in similar complexes
...
All of these haze-forming compounds can be removed by cold
stabilization and filtration; however, if hops are added after filtration then haze issues may arise
...
The pellitisation of hops is achieved after screening out debris and unwanted material by hammer
milling followed by compression into pellet form
...
In the manufacture of isomerised hop
pellets, magnesium oxide is added prior to pelletising to produce salts of the a-acids
...

The manufacture of hop extracts involves an extraction process where the hop oils and resins are dissolved into
a solvent, usually either ethanol or liquid CO2
...
The spent hops are then removed and the extract is concentrated by
evaporating the ethanol
...
The pressure of the chamber is then released causing
the CO2 to vaporise leaving behind the concentrated extract
...
Separation of the iso-a-acids from any remaining hop components is achieved by pH
reduction and removal of the formed precipitates
...
Although the addition of both pellets and extracts can be easily automated, the
use of extracts requires less robust equipment and greater control over accuracy
...
Type 45 pellets and extracts have added benefits over Type 90 pellets due to the
removal of unwanted vegetative material, which results in greater utilisation of the a-acids, reduced wastage/trub
and a reduced potential for haze issues due to reduced levels of hop proteins and tannins/polyphenols
...
Up to 95% utilisation can be achieved with isomerised extracts
when they are added post-fermentation
...
Hop oil extracts allow
advanced control over the hoppy character of the beer, which can be adjusted without altering bitterness levels
...
Reduced forms
of the iso-a-acids are known as tetrahydroiso-a-acids, hexahydroiso-a-acids or rhohydroiso-a-acids, depending
on the number of hydrogen atoms added during the hydrogenation process
...
Tetrahydroiso-a-acids and
hexahydroiso-a-acids also exhibit benefits in terms of head retention and foam stability
...
Malt is unloaded from the truck into a covered delivery bay before being moved to
either stainless steel or concrete storage silos
...
The handling of malt must be gentle to prevent
damage to the grain, which can shatter the husk and produce excessive dust levels
...
In order to ensure the load is a homogenous
batch of malt, the samples must be collected randomly using sample spears or more refined sampling systems
such as trickle filters or diverter systems, which can collect small continuous samples of malt during conveying
...
Removal of the malt from the silos for grist preparation is aided by the smooth walls of the
silos and hopper bottoms
...
During grist weighup the
malt is flowed over magnetic separators in a thin layer to extract any metal pieces, which can cause a spark
triggering dangerous dust explosions or damage equipment during processing
...
Separation of foreign
materials with a similar size to the grain but different densities can be achieved by equipment that use inclined
vibration methods or a transverse airflow
...
Other safety measures designed to prevent, limit or deal with dust explosions include good
ventilation, explosion vents, explosion sheets, pressure release pipes, explosion suppression systems and the
use of intrinsically safe electrical equipment (cleaning equipment, tools, radios etc) in high dust areas
...
The two main
categories of mills used in brewing are roller mills and hammer mills
...
When a
mash tun or lauter tun are used for wort separation, the integrity of the husk is critical as it forms a vital part of the
filter bed and helps maintain bed porosity
...
If mash filters are being used then the grist can be finer again and the porosity of the
filter bed is of little consequence so husk integrity is not important
...
In the case of a five-roller mill, one
roller is shared across two pairs
...
If the paired rollers are rotating at different speeds then they also impart shear forces on the grain
proportional to the difference in speeds
...
The gaps between the rollers are adjustable and one roller in each pair is spring loaded to prevent
irreparable damage from stones or loose machinery parts
...
These rollers should also be of a minimum diameter of
250mm to ensure a sufficiently angled nip to achieve good performance and throughput and should be run with a
peripheral speed setting of 2
...
0m/s
...
Prior conditioning of the malt by soaking or treatment with steam is commonly employed
to make the husk more pliable to ensure it remains intact during roller milling
...

Two-roller mills place all reliance for particle size control on one set of rollers and therefore the milling is slower,
significantly influenced by malt friability and homogeneity and the settings would need to be adjusted regularly to
compensate for different batches of malt
...
They are used in
combination with varying sized sieves to allow enhanced control over the final particle size and prevent fine grits
and flour from reducing the effectiveness of subsequent milling
...

Two- and four-roller mills are best suited for over- or well-modified malts and produce a relatively coarse grist,
which is suitable for mash tun separation
...
However, they are often used for under-modified malts
as they allow a finer comminution of the malt whilst retaining husk integrity for lauter tun separation
...
The increased cost can be justified in large breweries to save on extract and
volume throughput
...
The malt is
successively broken into smaller particles by impact with the beaters until the particles are sufficiently small
enough to pass through a sieve
...

Hammer mills achieve a finer grist (see table below) than roller mills without the preservation of husk integrity
...
Hammer mills give increased extract yield, more rapid
saccharification and less trub formation
...
While the capital costs of hammer mills are lower than roller mills they are more
expensive to run due to increased power consumption
...
Examples fraction proportions for grist produced from a six-roll mill and a hammer mill
Husk

Coarse Grits

Fine Grits

Flour

Six-roller mill

15%

30%

45%

10%

Hammer mill

5%

15%

40%

40%

26

Malt

air

Figure 1
...


Summary: Influence of malt conditioning and milling on extract recovery and run-off
Milling increases extract recovery as the comminution of the grain endosperm into smaller particles provides a
greater surface area for the extraction of carbohydrates during mashing
...
Increased levels fine grits
and flour from milling will slow mash tun or lauter tun run-off rates as they will reduce the porosity of the filter bed
and can increase the viscosity of the wort potentially causing set mashes
...


medium grits,
fine grits
and flour

coarse g

The preservation of husk integrity will improve run-off rates as the husk is a critical part of the filter bed and helps
maintain bed porosity
...
Malt conditioning also helps retain husk structure and involves prior treating of the grain with water
(soaking or steaming) to prevent too much fragmentation of the husk during milling
...
Preservation of husk
integrity The more extensive the conditioning, the more pliable the husk; however, extensive conditioning will
cause the endosperm to become less friable, which will decrease extract recovery as the particle size from
milling will be greater, unless mill settings are adjusted accordingly
...

The mashing process involves the hydration of malt and other grist components under conditions that can be

27

optimised to produce wort with the highest practical extract yield whilst ensuring desirable wort fermentability,
composition, flavour and colour in the shortest possible time
...

All of the enzymatic processes occurring during mashing are strongly influenced by mash conditions, particularly
temperature, pH and the grist to liquor ratio
...

Starch degradation is the most important of the enzymatic processes occurring during mashing that provides the
bulk of the fermentable extract in wort
...
Starch granules will gelatinise at temperatures above 60°C where
granule structure is disrupted making the starch molecules more accessible for enzymatic degradation
...
The molecules are further saccharified by b-amylase into individual maltose units by cleaving
every second a-(1,4) linkage from the non-reducing termini of the glucose chain
...
Therefore b-amylase
is capable of complete degradation of amylose molecules, but requires the complimentary activity of a-amylase
to open up the branched amylopectin molecules to provide new non-reducing termini
...
The actions
of the amylase enzymes will yield predominantly maltose units, some other simple sugars and limit dextrins
...

Protein degradation occurs predominantly during malting as protease enzymes are relatively heat labile
...
TSN is
comprised of foam-positive polypeptides and glycoproteins, acid polypeptides, which will form haze complexes
with tannins and small peptides that can be utilised by yeast and will enhance the mouthfeel and body of the final
beer
...
Protein degradation of under-modified malt may be required during mashing as undegraded endosperm
protein may impede starch availability for degradation
...
If the enzymes for the degradation of these
polysaccharides are not sufficiently available then the release of these polysaccharides can cause highly viscous
wort, poor extract recovery, impaired wort separation, sticky spent grains and beer stability issues
...
Some fermentable extract can be recovered from nonstarch polysaccharides; however, the levels are generally low unless commercial enzyme preparations are used
...
The optimum ranges of the important mash enzymes are displayed in the Table 2 below
and an example of a controlled mash profile is shown below
...
A pH range of 5
...
5 is
generally regarded to provide rapid starch degradation and enhanced carboxypeptidase or protease activity
...
In terms of the grist to liquor ration, enzymes will generally be most active with a low
grist to liquor ratio due to reduced levels of product inhibition; however, thicker mashes will provide the enzymes
with more protection from denaturing or inhibiting temperatures and pH
...
elevated denaturation temperatures) or to deal
with problem mashes
...
Optimum conditions for important mashing enzymes
pH Optimum

Temperature Optimum (°C)

a-amylase

5
...
8

70 – 75

b-amylase

5
...
6

63 – 65

Limit dextrinase

5
...
5

55 – 60

6
...
7 – 5
...
5 – 6
...
0

50

b-glucan solubilase

Carboxypeptidases

a-amylase activity

b-amylase activity

Tenperature

Limit dextrinase activity

72°C
65°C

proteolysis

48°C

1hr

Time

2hr

Figure 1
...
The mashing process will influence the
extract yield, fermentability, free amino nitrogen (FAN), total soluble nitrogen (TSN), viscosity, colloidal stability,
pH, colour and flavour of the wort
...

Before mashing in, the vessel is pre-filled with some hot brewing liquor (underlet) to preheat the vessel, prevent
blockage of the filter plates (if present) and minimise damage to the husk as it enters the mash tun
...
During mashing, soluble
components of the grist are leached out into the brewing liquor, while enzymes convert some of the insoluble
grist components into soluble and fermentable form
...
The key enzymes involved

29

in mashing are listed in Table 1 along with their substrates, products and optimal temperatures and pH
...
It is the varying temperature optima of different enzyme groups that form the greatest advantage of
temperature programmed mashing regimes, where the activity of these groups is controlled by means of a
number of temperature ramps and temperature stands
...


30

Table 1
...
3 – 5
...
4 – 5
...
0 – 5
...
0 – 6
...
7 – 5
...
5 – 6
...
0

31

Optima

Single temperature infusion mashing regimes involve a single strike temperature (usually around 65°C) achieved
by the equilibration of the vessel, brewing liquor and grist temperatures
...
Single
temperature mashing regimes are commonly used with mash tuns designed also for wort separation
...
The
vessel has filter plates for wort separation and sparge arms to distribute hot liquor over the bed to flush residual
extract from the grains during wort separation
...
The form of this temperature control varies including, (i)
modern systems controlled entirely by steam coils, jackets and sometimes direct injection of treated steam, (ii)
decoction systems controlled by removal of portions of the mash, which are separately heated and added back to
the main mash, or (iii) double mashing where the addition of separately cooked cereal adjuncts is used to
achieve a temperature ramp in the main mash
...

Temperature programmed mashing vessels do not have filter plates and rely on the use of a lauter tun or mash
filter for wort separation
...
The grist to liquor ratio is often lower to protect the enzymes from product
inhibition and to make transfers between vessels easier
...
The vessel shape and stirrer design
are optimised to ensure adequate mixing with minimal shear forces exerted on the mash, which can damage the
husk, produce fine malt particles and physically extract b-glucan from the malt, which can hinder wort separation,
extract recovery and cause colloidal instability of the beer
...


32

Table 2
...
Examples of mash profiles using different types of mashing regimes

Details: Design and operation of an infusion mash tun, lauter tun and mash filter for wort
separation
After mashing, the sweet wort must be separated from the spent grain, usually by means of an infusion mash tun,
lauter tun or mash filter
...

The grain bed acts as the filter medium in infusion mash tuns, lauter tuns and early mash filter models; however,
modern mash filters use a polypropylene sheet, which is sufficient for achieving bright wort without any reliance
on the grain bed
...
However, the grain husk and rest of the grain
bed is susceptible to compression, which can have adverse affects on run-off rates and overall mash filtration
...

Sparging is common to all wort separation techniques where fresh hot liquor is used after the initial strong wort is
collected, to flush remaining wort through the grain bed and to extract residual soluble components from the

34

grains
...
Sparging is important for extract recovery and results in the collected wort becoming
progressively more dilute as wort separation continues
...
However, the last runnings are often discarded due to
the increased extraction of deleterious grist components including lipids and polyphenols
...
Infusion mash tuns are simple insulated
vessels often with steam jackets, which are used only to preheat the vessel
...
Infusion mash tuns rely on air entrapped
in the mash from mashing in to float the grain above the filter plates
...
This also prevents distinct channels forming, which would reduce
the extract recovery from sparging
...
This requires careful control of the wort runoff and sparge rate often controlled by monitoring the differential pressure across the grain bed
...

Lauter tuns require the mash to be transferred across from the mash tun, therefore a lower grist to liquor ratio is
often used, which is also beneficial for mashing due to reduced product inhibition of enzyme activity
...
The larger surface area of the filter plates in the lauter tun allows for a shallower
grain bed and the rakes are used to spread the grain evenly over the filter plates
...
The rakes are often automatically controlled and the bed depth and differential pressure across the bed will
generally dictate the height and speed of the rakes
...
The mash is also transferred into the lauter
tangentially since entrapped air is not required to float the grain above the filter plates
...
After the last runnings are
drained through the grain bed, the rakes can be rotated through 45-90° to direct the spent grain down discharge
ports into hoppers or pondorfs below
...
The
multiple chambers allow a considerable increase in the filtration area and a more shallow grain bed
...
The shallow bed depth and action of the inflatable membrane allow mash filters to be used in conjunction
with hammer mills, which will maximise extract recovery and allow the use of under-modified malt since physical
disruption of the endosperm will allow enhanced extraction into the brewing liquor
...
Initial filtration is achieved once the
chambers are full and wort is forced out through the filter sheets
...
Sparge water is then filled
into the chambers and allowed to push the membranes back to their deflated position
...
The filter is then drained and each
plate/frame is opened in succession allowing the spent grains to fall out into a hopper below
...

Each tube is connected to external pipework and individual wort pumps and as the vessel is filled from the bottom, each
line is recirculated as the tubes become covered
...


•

Decanting centrifuges

•

Rotary vacuum filters

•

Vibrating membrane filters

•

Vibrating screen filters

•

Cross-flow filters
...
The rate
and occurrence of these reactions and changes are dependent on boil temperature, boil duration, boil intensity, surface
temperatures, turbulence, vessel design and the presence of other reactants or additions to the boil such as oxygen or antifoam
...
Microbiological stabilisation
Any viable microorganisms (bacteria, yeast or fungi) in the wort are destroyed by the heat of the boil preventing them from
passing through into fermentation where they can compete with the yeast causing altered fermentation performance, overattenuate the wort or produce hazes and off-flavours in the final beer
...

2
...
Protein degradation products
also form complexes with polyphenols, which precipitate on cooling to form cold break along with unisomerised hop resins
...
Excessive amounts of cold break can be detrimental as it can coat yeast cells causing altered fermentation
performance, impart sulphury flavours in the beer and cause difficulties during beer filtration
...
Protein denaturation
Heat-sensitive proteins including mash enzymes are denatured and inactivated effectively setting the carbohydrate spectrum of
the wort
...

4
...
1 to 0
...
A lower pH improves protein coagulation,
vicinal diketone reduction (during fermentation and maturation), yeast growth and microbiological stability; however, also
reduces hop utilisation and colour formation
...
Flavour and colour development
During boiling the flavour and colour of the wort changes due to a number of reactions
...
The solubilization

36

and isomerization of hop a- and b-acids will develop the bitterness of the wort while the solubilization of hop oil will contribute
hoppy aromas to the wort
...
The
oxidation of polyphenols and melanoidin formation will also help develop wort colour imparting brownish, reddish tinges
...
Vapourisation of volatiles
During boiling a lot of volatiles are vaporised and lost from the wort
...
In order to retain some of the hoppy
aroma from hop oil, aroma hop varieties may be added late in the boil to preserve the heavier esters and ketones
...
Oxidation
Oxidation is more rapid during wort boiling and can cause flavour instability of the wort and beer
...
Oxidized polyphenols will darken
wort and react more readily with proteins
...

8
...

9
...
Wort aeration is
generally performed on the cold site of the wort cooler in order to minimize unnecessary oxidation
...
Most kettles have an internal calandria, which is essentially a tube-in-tube heat exchanger that produces
intense heat at the centre of the vessel driving the wort upwards to a spreader, which is designed to achieve a “full rolling boil”
...
The kettles have a stack and vapour condenser for the collection and release of steam and volatiles
...
This heated water can then be used for cleaning or to
preheat the wort of subsequent brews as it enters the kettle
...
The precipitation of proteins can be aided by the addition of kettle finings, which bind to positively charged proteins by
electrostatic attraction
...
Without sufficient clarification, these materials can coat
yeast cells causing altered fermentation performance, reduced attenuation of the wort and increased susceptibility to microbial
infection
...
Some brewers argue that a small amount of trub carryover is desirable as it encourages yeast
growth, presumably because it is rich in unsaturated fatty acids
...
The hopback is a vessel with a false bottom of filter plates
and acts in a comparable manner to a lauter tun
...
The hop strainer uses a screw conveyor to squeeze the hop material against a mesh
screen to remove the entrained wort
...
The hop strainer will more effectively remove any entrained wort; however, the wort will
require secondary clarification since finer trub material will be able to pass through with the wort
...

Basic sedimentation can be utilised for wort clarification as with cool ships or sedimentation tanks
...

Centrifuges can be used to mechanically enhance the settling process by replacing the gravitational force with an artificial
centrifugal force
...
The mass of the solids moves them to the outer surface of the discs where they
collect until being discharged by a rapid opening and closing of an annular gap into a discharge line
...
They also incur high capital costs, high running
costs and are susceptible to damage from stones from the malt or hops
...
Filtration of wort can be used for wort clarification with great
results; however, it is unnecessarily complicated, labour intensive and incurs ongoing material and disposal costs
...
The whirlpool is a simple, circular
vessel where wort is introduced tangentially producing centrifugal force by creating a whirlpool effect
...
To maximise this effect, whirlpools require a high transfer rate from the kettle and the inlets are
designed to reduce velocity and subsequent shear forces whilst maintaining a high volume flow rate
...
After the optimised
circulation time is reached, the clarified wort is drawn from above the trub cone through outlets on the side of the vessel at
varying heights
...
Whirlpools are very simple with very few moving parts
and therefore after optimisation they require very little maintenance or service
...
Spent trub cannot be disposed of to drain due to its very high biological oxygen demand and is therefore generally
added to the spent grain where it is used as cattle food
...
It is vital that dissolved oxygen is present at sufficient levels
when yeast is first pitched into the wort as there is an absolute requirement of oxygen for the synthesis of unsaturated fatty
acids and sterols
...

The level of oxygen required depends on the yeast strain, pitching rate and wort gravity; however, generally falls between 7 and
18mg/L
...
Insufficient oxygenation of wort would limit yeast growth, which would alter the fermentation of the wort
potentially causing atypical flavours, haze and stuck fermentations
...
However, the aeration of the
wort on the hot side of the heat exchanger would have the advantage of minimising any microbial risk
...
The air or oxygen is generally injected directly into the wort stream using a disc spreader to help dissolve the
oxygen
...


38

CLEANING, HYGIENE AND EFFLUENT
Details: Principles of CIP and cleaning agents
Good hygiene standards and cleaning are necessary in the brewhouse to ensure that no flavours, foam inhibitors or hazeforming compounds from ingredients, residual detergents or biomass are imparted into the beer and to prevent the
contamination of the mash or wort with viable spoilage microorganisms
...
If wort for a clear-bottle product is to be produced using reduced forms of
iso-a-acids then it is critical that all residual hop resins are completely removed otherwise the final product is highly susceptible
to photooxidation and the development of lightstruck aromas and flavour
...
The contamination of
cooled wort can be particularly disastrous as the chance of infection and beer spoilage during fermentation is high since there is
a wide range of nutrients available, favourable temperatures for growth and reduced antimicrobial factors when compared to
fermenting wort
...
Contaminations prior to wort boiling may be destroyed in the kettle; however, detrimental changes to the wort can still
occur during mashing, lautering and the early stages of boiling (for thermotolerant species)
...
Post-rinsing may be performed in several steps to remove traces of detergent with water before sanitizer rinsing
...
The effectiveness of CIP processes depends on plant
design, the detergent and sanitizer being used and the process conditions under which the CIP operates
...

o CIP plants should be large enough to allow sufficient duration and volume of cleaning chemicals and rinse water
during CIP processes
...

o Reverse CIP circuits should be possible for some equipment (eg
...

o In-line sensors (conductivity probes, temperature probes, pH probes, flow sensors etc) on the CIP circuit allow
monitoring of the CIP progress and effectiveness as well as the potential for automation of CIP processes
...

o Multi-use systems or recoverable systems allow cleaning chemicals to be recovered either completely or partially for
reuse
...
However, such systems
require high initial capital costs, are relatively inflexible regarding choice of chemicals and require ongoing
maintenance and monitoring of chemical quality
...

o The CIP circuit should consist of pipework of the same diameter to prevent slower (and therefore reduced) cleaning
through sections with larger diameter pipework
...

o Valves on pipework should be of hygienic design and potentially able to be cleaned in place, otherwise manual
cleaning of valves must be performed routinely
...


§

Vessel Design
o Vessels should drain well
...

o Vessels must have minimal edges or crevices where soil can accumulate
...


§

Construction Materials
o Materials must be capable of withstanding strong detergents and sanitizers without corrosion or deterioration (usually
a suitable quality of stainless steel)
...


39

Cleaning Chemicals
Detergents are commonly composed of surfactants, emulsifiers and sequestrants
...
There are different types of detergents available including alkaline detergents (eg
...
sodium tripolyphosphate), organic compounds (eg
...
Calcium or
other mineral scale can often be an issue with brewery vessels
...

Sanitizers are often employed separately to detergents; however, there are some bacteriocidal detergents available for
combined cleaning and sanitizing (eg
...
There are three modes of action for sanitizers, (i) chemical oxidation (eg
...
anionic surfactants, ampholytic
surfactants, quaternary ammonium compounds), and (iii) poisoning (eg
...
It is also important to note that steam and the boiling of wort in-vessel are highly
effective ways of achieving sterilisation without the use of sanitizers
...
However, it is crucial to ensure no antagonism between the detergents or sanitizers is likely to occur otherwise a
reduction in effectiveness will be observed
...

Process Conditions
The process conditions of CIP procedures are critical for optimisation of cleaning effectiveness
...
High-pressure
systems can remove soil with reduced detergency action and liquid volume while turbulence and increased flow rates will help
lift and remove soil during rinsing
...
The most suitable temperatures for the different stages of cleaning systems
depend on the soil present and the chemicals being employed
...
More sensitive methods usually start with swabbing or rinsing the surface and testing the swab or rinse water for
the presence of any viable microorganisms
...


•

Microscopic Analysis
o Sample is assessed under the microscope for visualisation of cells
...
Only suitable for large contaminations
...

Assessment for growth is generally in the form of turbidity, presence of gas bubbles or a colour change
...
Assessment for
growth is in the form of visual or microscopic counts of microbial colonies, which can be accompanied by selective or
differential properties in the media
...
ATP is extracted from cells using a detergent and the amount of ATP is assessed by measuring the light
produced from an enzymatic reaction that requires ATP
...

Careful aseptic technique should be used when collecting swabs or rinse water samples and the area swabbed or rinsed should
be representative of the entire surface being assessed with larger samples being more accurate
...


40

Details: Brewery liquid effluent
The principal sources of brewery liquid effluent are from brewing liquor treatment, CIP processes (rinse water, detergents,
sanitizers), weak process streams (eg
...
kieselguhr), product losses (wort, yeast, deaerated liquor, beer) and cooling systems (eg
...

Brewery liquid effluent is composed of biodegradable organic compounds, suspended solids, dissolved CO2, trace organics, oils
and solvents, heavy metals and relatively high levels of nitrogen and phosphorous
...

Table 1
...
The metabolism of biodegradable organic compounds will produce noxious gases and form an oxygendeficient environment, which will have adverse impacts on the ecology of the watercourse
...

Trace organics, oils, solvents and heavy metals can be toxic to aquatic life while nitrogen and phosphorous will encourage
undesirable microbial growth and algal blooms
...
Many breweries utilise a balance tank or wet well to reduce the variability and to allow pH adjustment of the
effluent before being discharged to municipal sewers
...


6
...

Before brewery effluent is suitable for biological treatment it should be collected in a circulating balance tank to dilute strong
chemicals, reduce variability of the effluent, allow time for oxidizing agents to react and provide an opportunity for pH adjustment
(using acid, alkaline or CO2) and temperature control (if circulated through cooling towers or heat exchangers)
...
Solids removal is also needed to reduce effluent loading and
to prevent any interference with biological processes
...
Other methods for fine solids removal can
include cyclones, centrifuges or cross-flow filtration
...
Microbiological digestion is also suitable for secondary
treatment of brewery effluent prior to tertiary treatment (filtration, reverse osmosis etc) for the production of reusable water
...
They are generally either activated sludge systems or attached
growth systems where the microorganisms form a biofilm on a packed bed of a particular medium
...
The biogas produced can be
condensed or burned before release to the atmosphere, which will limit any odour emissions
...
The relative
advantages of the two systems are outlined in Table 1 below
...
The relative advantages of aerobic and anaerobic digestion systems for brewery effluent treatment
Aerobic Digestion

Anaerobic Digestion

Removes more BOD
No requirement for biogas facilities

Requires reduced building area
Reduced capital costs
Reduced bioreaction time
Reduced biomass production and disposal requirements
Increased capability for odour control

Summary: Methods of Effluent Analysis
Chemical Oxygen Demand (COD)
A measure of the amount of oxygen (mg/L) required to completely oxidise the sample
...


Biochemical Oxygen Demand (BOD)
A measure of the organic pollutant strength, which is equal to the mass of oxygen (mg/L) consumed by organic matter during
aerobic aerobic decomposition under standard laboratory conditions
...
Suspended solids will usually contribute to
the turbidity of the sample
...
These solids form the residue that
remains after evaporation and drying (assuming that the suspended solids are removed prior to analysis)

---