Brew manual.pdf

MANUAL FOR BREWING AND BEER
PRODUCTION
DASHEN DEBRE BIRHAN BREWERY

PROCESS OF BREWING
Date: 01/09/18
BREWING AND BEER PRODUCTION
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MILLING
Objective of Milling
The objective of milling is to provide optimal conditions for enzymatic activities during mashing
for solubilation of fermentable carbohydrates and to provide best possible mash separation thus
highest possible yield.
This is obtained by:
- Crush the husks gently – preferably longitudinally – to expose endosperm.
- Obtain a complete disintegration of the endosperm to make all of its good constituents
accessible to enzymatic processes.
- Prevent extraction of unwanted substances during mashing.
- The ideal milling is hardly obtainable, but a suitable compromise should be obtained
During mashing the enzymes must be able to get at the malt contents in order to degrade them.
The larger the surface area available for enzymic attach, the better the breakdown of the malt
material. After mashing the wort must be run off.
MASHING
Mashing is the most important process in wort production. During mashing the grist and
water are mixed together (mashed) and the contents of the malt are thereby brought into solution
and the extract obtained. The transformations during mashing are very important.
The process of mashing refers to the conversion of brewing materials in the presence of
enzymes, into a fermentable extract suitable for yeast growth and beer production.

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Only soluble substances can pass into beer. It is therefore necessary to convert the insoluble
materials in the grist into soluble material during mashing.
Soluble substances are:
 Sugar
 Dextrin
 In organic substances
 Certain proteins
Insoluble substances:
 Starch
 Cellulose
 High molecular weight protein
 Other compound which remain in spent grain
All soluble substances that go in to solution is called extract.
Q1. What is the purpose of mashing? The aim of mashing is to form an extract with a desired
profile of sugars and a desired level of proteins and other minor chemical constituents.
Q2.What is enzyme? Enzymes is biological catalyst in the form of protein that catalyze
Chemical reactions

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Properties of enzymes
Their property is their ability in breaking chemical bonds in their substrate. Enzymic activity
depends on
 Temperature
 PH
 Time
 Mash process-thickness &thinness
 Dependence of enzyme on temperature
 Enzymes activity reach maximum at optimum temperature whereas its activity retard
when its temperature less than optimum. Enzymes inactivate when temperature higher
and exceed its optimum value which is called Denaturation.
 Dependence of enzyme activity on PH
 The enzyme activity reaches an optimum value, which is specific for each enzyme, and
decrease at higher or lower PH value.
 Dependence of enzyme activity on the mashing process
 Enzyme activity, particularly that of the β-amylase is dependent on the mashing process.
That is thicker mashes receive longer enzymatic activity than thinner mash.

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Degradation of substances from malt (mash)
 Starch degradation
Starch degrades to sugar and limit dextrin which is not stain by iodine. If it not
completely degrade it cause starch haze.
Starch degradation has three main steps:
a. Gelatinization: (@59 to 65o
c)
- It is an incorporation of hot water with starch molecule then starch
molecule which loss its crystal state and become amorphous.
- An increasingly viscous(sticky)solution is formed
- It is precondition for a complete breakdown of the starch.
- It is not enzymatic process and no metabolic breakdown.
b. Liquefication:
- Is the reduction of viscosity of the gelatinized starch by α-Amylase
- During liquefication high molecular chain starch is rapidly broken
to smaller chain by alpha-amylase and slowly by β-amylase.
c. Sacharification:
- It is complete degradation of starch to maltose. Here α-Amylase breaks amylose and
amylopectin to form dextrin
- ß-amylase splits off groups of two residue ( maltose) from the new
non-reducing ends produced on these small chain
- it is checked by iodine test

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Degradation products are:
 Limit dextrin – which are not ferment
 Maltotriose - is ferment by all type of yeast but when maltose has been fermented. In
general it is late fermenting sugar.
 Maltose – maltose and other disaccharides are easily and rapidly ferment by yeast.
 Glucose – is the first sugar used by yeast.
The percentage of fermentable sugar in total wort determines the attenuation limit
(apparent degree of fermentation). The normal composition of fermentable extracts in
pale beer with an apparent degree of attenuation of 80%. But this composition is very
dependent on mashing procedure. The attenuation limit establishes the potential alcohol
content of the beer and consequently has a decisive influence on the character of the beer.
The proportion of fermentable sugar s is determined by the variable activity of the
enzymes. Consequently the attenuation limit is also established during mashing.
NB. The amount of various sugar and dextrin in the wort affect both the course of
fermentation and the quality of beer.
The important factors during mash degradation are:
- Temperature
- Mash PH
- Mashing time
- Mash concentration

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Effect of temperature on starch degradation
 By mashing @ 62 to 65o
c (opt. temperature for β-amylase), the highest possible maltose
content and highest attenuation limit is achieved. Maltose rich wort ferment more quickly
and hold the yeast longer in suspension and this result high alcohol in beer and less
apparent extract.
 By mashing @ 72 to 75 o
C (opt. temp. for α-Amylase), long rest time result a dextrin rich
beer with low attenuation limit and high apparent extract with less alcohol.
- Mashing –off temperature of 76 to 78o
c
Effect of mashing time on starch degradation
Two time dependent stages in enzyme activity can be distinguished
1. The maximum enzyme activity is reached after 10 to 20 min.
2. After 40 to 60 min the enzyme activities decrease.
Effect of mashing PH on starch degradation
Enzymes activity is very dependent on the pH. It has also been shown that the β-amylase in the
mash has a pH optimum of 5.4 to 5.5, and α-amylase at 5.6 to 5.8. By mashing within a pH range
of 5.5 to 5.6, which can be regarded as the compromise pH for both amylases, the extract content

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can be increased in comparison to that obtained at a higher pH value. More fermentable sugar is
produced and the attenuation limit is higher.
The "normal" mash pH is however considerably higher (depending on the composition of the
brewing water and the malt), being 5.6 to 5.9. It is therefore advantageous, when mashing, to
lower the pH value to 5.5 to 5.6.
However, in order to limit lipoxygenase activity in the mash and husk extraction during filtration
it is preferable to mash in at 5.2 pH. Lipoxygenase is an enzyme that can increase the level of
trans-2-nonenal in beer (an undesirable papery flavor). The lower initial mashing pH does not
seem to affect the α-amylase and β-amylase activity during mashing. A lower pH will also
reduce color formation and beneficially reduce the leaching of husk
Effect of mash concentration on starch degradation
In thin mashes more extract goes to solution but thicker mashes protect the enzymes from too
rapid thermal inactivation.
MASHING IN
Mashing in is the named used for the extremely through mixing of the grist (milled malt) with
water (mashing liquor) at specified mashing in temperature.
Addition of the brewing water (brewing liquor)

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The ratio of the grist to the brewing liquor used before sparging is important to determine the
concentration of first wort. It can be calculated that
 100kg of grist with 3 hl of liquor (1:3) produce 20% of first wort.
The mash is made 5 to 6% strong than the original gravity of the beer should be; for 11-12% beer
at 16-18%. Sufficient water can be passed through spent grain to wash out sugar.
Example:
How many hl of water must be used for mashing in to obtain 25% wort with grist ratio of 6100?
Solution:
100kg produce 20% wort with 3 hl water
Therefore, 6100kg produce 20% wort with
(6100*3)/100=183hl water
Hence to get 25% of first wort
(183*20)/25=146.4hl water
NB. The volume of the grist mashed in increase in 0.7 to 0.8 hl /100kg grist
So, 146.4+6100(0.7/100) = 146.4+42.7
=189.1hl mash volume

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Mashing in temperature
It can be performed at any temperature. But it influenced by the optimum temperature of enzyme
which one wants to activate initially.
Optimum temperature of the enzymes:
 55o
C for protein rest
 62 to 64 o
C for maltose production rest( for activation of β-Amylase )
 70 to 72 for Sacharification rest ( for activation of α-Amylase)
 75 to 78 o
C for final mashing temperature
Temperature Function
Mash in 55o
c Protein rest
Rest to 62o
c β-Amylase rest
Rest to 72o
c α-Amylase
Rest to 78o
c Mashing off
First wort and second wort
The wort draining off from the spent grain is called first wort. When this wort has been drained
from the spent grain the latter still contain extract. This extract must now be recovered by hot
water which is called sparging.

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The amount of sparging water used depends on the amount and concentration of last run and the
concentration to be reached in wort kettle.
WORT BOILING
Importance of wort boiling
During wort boiling a number of important processes occur.
1. Extraction and transformation of hop components
During boiling the important components of hop for beer production are produce, like
- Hop resin or hop bitter substance which give bitter taste
- Hop oil
- Hop polyphenol
2. Formation and precipitation of protein-polyphenol compound
- During boiling high molecular weight protein coagulate and they
bond with the polyphenols of hop and malt.
3. Evaporation of water
- This improves the yield since the extract content of the wort
increase.

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4. Wort sterilization
- Many bacteria and moulds which if they not destroyed can change
the flavor of beer. So boiling the wort will kill all microorganisms
from wort in wort kettle and sterilize.
5. Halts the enzyme activity
- During boiling the few enzymes still present are completely
destroyed which helps subsequent uncontrolled alteration of the
wort composition.
6. Thermal exposure of wort( increase wort color)
- During boiling amino acid react with reducing sugar to increase the
color and the reducing potential of the wort.
7. Lowering of PH of the wort
- The wort becomes slightly more acidic since the melanoids formed
on boiling are acidic and the hops also contribute some acid.
8. Formation of reducing substances
- Reducing compounds are capable of acting as oxygen scavenging
compound.
Example: melanoids
Polyphenols
9. Evaporation of undesirable aroma substances( volatile compounds)
- Wort contain a range of molecules volatile aroma substances which
are partly have negative effect on beer aroma

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- During boiling this volatile compounds from malt and mash are
removed with the vapor.
10. Increase the concentration of wort
Important ions in brewing
Calcium
- Of the ions required for brewing, calcium is by far the most
important. This is because of the acidifying effect that calcium has
on the wort.
- Wort contain large amount of phosphates derived from the malt
which have buffering effect and this keep the pH of wort higher
than desired. Here calcium ions precipitate as insoluble calcium
phosphate and release hydrogen ion into the wort.
3 Ca2+
+2HPO4
-2
Ca3 (PO4)2
-
+ 2H+
A combination of the process of calcium ions and the decrease in pH has number effects on the
brewing process.
- The lower pH improves β-amylase activity and thus wort
fermentability and extract.
- Calcium has beneficial effect on the precipitation of wort protein,
both during mashing and boiling.

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- Calcium ion protects the enzyme α-Amylase from inhibition by
heat.
- Drop in pH afford both wort and beer resistant to microbiological
infection.
- Calcium precipitate oxalates as insoluble calcium oxalate.
- The presence of calcium reduces color formation in wort kettle.
- Calcium ions encourage yeast flocculation.
Magnesium:
- It is used as a co-factor for the production of certain enzymes
required for the fermentation process.
However,
- Excess magnesium can interfere the reaction of calcium with
phosphate.
- Above about 20mg/l can give beer a sour and better taste.
- Excess magnesium has a laxative effect.
Sodium:
- The flavor is more acceptable when the sodium is present as
chloride than as sulphate.
- Excess level of sodium imports a sour and salty taste.
Potassium:
- is like magnesium ,a yeast co-factor

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Sulphate & chloride:
- Sulphate give beer a drier, more bitter flavor, whilst chloride
imparts palate fullness and to an extent sweetness. However what
we noted is that is ratio of concentration of these two ions that is
significant (2:1).
- Sulphur is essential for the fermentation process, since the yeast
need to manufacture the Sulphur containing amino acid (cysteine &
methionine).
Trace ions: - iron, manganese, copper, zinc
Zinc: - Is the most important trace element in wort.
- It assists protein synthesis in yeast cell and controls nucleic acid
and carbohydrate metabolism.
- It also a necessary contact building blocks in alcoholic
fermentation.
WORT SETTLING
The break from the wort is now called hot break. It consists of large particles which are slightly
heavier than the wort and in general settle down well to form a compact mass. The coarse break

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must be removed since it is not only of no value in further beer production, but also actually
detrimental to quality.
COOLING AND CLARIFYING OF WORT
Because yeast can only live and ferment at low temperature so the hot wort must be cooled to 5o
c
to 6o
C or after 7o
C to 10o
C. During this process the initially clear wort becomes turbid because of
the formation of cold break. Rapid fermentation and maturation require optimal remove of this
cold break on cooling. Because of its small size, cold break settle only with great difficulty. It
has property of adhering to other particles, like yeast cell or air bubbles. When it adheres to yeast
cells, it decrease the yeast contact surface and thereby reduce the fermentation rate. This is
referred as “coating” the yeast. (This is why we remove dead cell with cold break)
WORT AERATION
Yeast needs oxygen for production of new cell substances, in particular fatty acids and
ergosterin. The fatty acids form the main component of cell membrane in the yeast. But during
aeration of wort a great care should take because excessive aeration results:
- More foam formation
- Loss of ingredients which have a positive effect on the foam
- Oxidation stress on yeast which can lead to damage to the function
of membrane
- More energy loss

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BEER PRODUCTION
(FERMENTATION, MATURATION AND FILTRETION)
To transfer wort to beer, the sequence in the wort must be fermented by enzymes in yeast to
ethanol and carbon dioxide.
This also result in the formation of fermentation by-products with which have a considerable
effect on the test, aroma and other characteristic properties of the beer.
When we think about fermentation there is always the process parameter that helps us to get the
desired quality of the final beer.
Process parameters:
- Fermentation Temperature
- Fermentation time
- Counter pressure(back pressure) in fermentation
- Production equipment
Fermentation
In well aerated and cooled wort yeast pitches and fills to CCT. After the yeast is added in wort, it
exercise a new environment for shock effect; a different temperature, PH, a high concentration of
sugar etc., for very short time (lag phase). During this time before it comes into closer contact

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with the new medium, however, the yeast cell firstly draws on stored reserve substance
(glycogen) which immediately provides it with initial energy.
After adaptation yeast cell then quickly begins to break down the sugar by means of
respiration and accelerates fermentation which is immediately intensified. At the same time the
yeast begins to form new cell substances while it increasingly propagate by means of buds
(logarithmic phase). This phase is the most important stage in fermentation, where the wort
flavor disappears and it replaced by a green flavor.
The log phase slowly comes to an end when the supply of fermentable sugar has been greatly
reduced and finally almost nothing fermentable remains; fermentation is completed. The yeast
begin to flocculate, multiplication no longer occurs, alcohol and co2 in the form cell toxins
increasingly inhibit the yeast cell. The yeast cells slowly sink to the bottom where they can be
harvested / purged.
Primary fermentation temperature and time
From 10o
c to 13o
c for 72hrs the primary fermentation usually start. During fermentation a
number of metabolic by-products from yeast are passed into the beer, some of which either react
with each other or change their amount and composition. These fermentation by-products have
decisive effect on the flavor and quality the being produced.
Fermentation by-products:

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- Diacetyl
- Higher alcohol
- Esters
- Aldehydes
- Sulphur compounds
Form these by-products like diacetyl, aldehydes and Sulphur compounds; which give the beer
unclean, immature and unripe, unbalance taste and aroma are removed by yeast biochemically
from beer during maturation. The removing of these green aroma substances is essential criteria
for the maturation of beer.
Maturation
During maturation yeasts consume their by-products biochemically. Mature beer aroma
substances essentially determine the aroma of beer and their presence in defined concentration
ranges is a necessary requirement for a high quality beer. The formation of maturation beer
aroma substance is significantly affected by the yeast strain and fermentation conditions and is
completed at the maturation stage.
Besides the formation and removal of by-products a number of other reactions and changes
occur during fermentation:
 Changes in the composition of nitrogen compounds
Nitrogen compound excrete from yeast to beer during primary fermentation stage and
autolysis of the yeast cell. But of these two stages there is positive negative effect on beer

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- Palate fullness
- Bitterness and polyphenol
- Foam stability
- PH decrease /increase
- Color
- Beer stability
 Lowering of the PH value
The PH decrease substantially during fermentation particularly in the initial and
logarithmic growth phase as result of
- Formation of organic acid by deamination
- The use of phosphate ions by the yeast
- The uptake of ammonium ion (-NH3) by yeast
- The uptake of potassium ion by the yeast and release of hydrogen
ion
A beer pH between 4.2 and 4.4 is aimed for;
* pH of less than 4.4
- accelerates precipitation of colloidal unstable Protein-polyphenol
complex
- produce faster maturation

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- refines the beer taste and
- essential biological stability of beer
 change in oxygen content(redox properties)
During fermentation of wort there is an increase in utilization of dissolved oxygen
from wort and this reducing the oxygen content of the beer.
 Changes in the beer color
During fermentation there is discoloration of some substance caused by the dropping
in pH and adsorption of highly colored substances on the yeast cells or precipitation in
foam head or tank bottom. Because of decrease in pH during fermentation there is
precipitation of bitter substances and polyphenols.
 Carbon dioxide content of beer ( dissolving of CO2 in beer)
The co2 content of beer is one of its most important quality criteria. The solubility of
co2 in beer depends on:
- Temperature - solubility increase with decrease the beer
temperature
- Pressure on the liquid – solubility increase with pressure increase.
Clarification and colloidal stability of beer
The last phase of the maturation process serves to clarify the beer and improve its filterability
and also increase its colloidal stability.

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Fermentation temperatures
With regard to temperature control the pitching temperature, primary fermentation temperature,
maturation temperature and Lagering temperature are important.
 Pitching temperature
The pitching temperature is usually raise or decrease based on fast or slow fermentation
that we want. But usually the pitching temperature is from 5o
c to 7o
c or 8oc
to 9o
c.
 Primary fermentation temperature
This temperature is decisive factor for our beer quality and it is usually starts at 10o
c to
13o
c for 6 to 8 days based on rate of fermentation that we need.
 Maturation temperature
During this fermentation stage most of the fermentation by-products are remove
biochemically and the beer become mature. Its temperature is 14o
c based rate
fermentation for 3 to 6 day until the extract comes to limit. At end of this stage we check
the amount of VDK (diacetyl) < 0.10ppm.
 Lagering temperature
After the VDK reach to standard, the beer cools to 1.5o
c. When reach from 14o
c to 1.5o
c
we shift its temperature to -2.5o
c for more than 3 days for colloidal stability of the beer.
Pressure regulation

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When the secondary fermentation (maturation stage) started the extract of beer is rapidly
decrease due fasten activity of the yeast. If this fast activity of yeast is not regulate the final beer
quality will not be as desired. Therefore, in order to limit the activity of the yeast and force to
settle it for further recollection and for dissolving CO2we can pressure @ 0.5 bar when the
extract is less than 5o
p.
CO2 Recovery
During fermentation there is around 4kg/hr CO2 is produced. This CO2 is a respiratory
poison!After 10-15hr of fermentation the CO2 purity will be > 99%in laboratory purity meter and
this > 99% pure CO2 send to CO2 recovery for further purification.
Yeast cropping
Yeast cropping is an extremely important chapter for the brewer; when we crop yeast we have to
consider two basic things in cropping:
- When we recollect yeast
- How we recollect yeast
Time of yeast cropping
The yeast should be collected as often and early as possible. There are several reasons for this:
 The yeast does not settle as desired.

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 As the beer increasingly matures, the yeast excretes high molecular
proteins which can no longer be absorbed; these have a negative
effect on head retention.
 With increasing maturation and Lagering,the yeast excretes a
protein A which leads to a considerable deterioration of the foam.
 Yeast gets in to autolysis this causes increase in PH beer.
 Due to saturation of CO2 yeast die.
 Through the release of fatty acids, amino acids and proteolytic
enzymes the flavor and foam stability are permanently damaged.
 The PH of beer increase.
Methods of collecting yeast
The yeast is collected in the tank cone at end fermentation. From the cone the yeast can be;
 Collected by making use of the pressure of the column of beer above it or
 Additionally, an appropriate pump can be used to keep the volume flow constant
It is important that the yeast collect slowly. If the yeast is removed too quickly beer will be
drawn. When you collect yeast should give great care for pressure balance between the CCT and
yeaster tank. If you collect yeast from 0.5 bars CCT pressure to pressure less yeast tank the
pressurized CO2 expand very suddenly. This causes stress situation for yeast which we have
recollected. This has to be taken in to account when collecting the yeast, unless the yeast is
immediately pumped in to a container with counter pressure and through the bellowing in of

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sterile air, subject to aeration and CO2 washing out before the pressure is expanded. The removal
of the CO2 and supply of oxygen are very important for the vitality of theyeast if it is to be
immediately reused.
Temperature of yeast storage
The longer the yeast has to be stored, the lower the storage temperature has to be. A short and
cold storage is always the most suitable method for storing yeast. Even in the case of warm
fermentation and maturation, the yeast retains its fermenting properties if it has been stored cold
between the generation. The only factor which does notfavora low storage temperature is that the
yeast may tend towards shock excretion because of the negative temperature difference, where in
particular amino acids and nucleotides are passed into the wort, with only the former being taken
up again after a few hours.
In the case of short temperature storage, cooling should occur
 At pitching temperature, but not higher than 8o
c
 At 3 to 5o
c if storage is to take place the weekend.
In case of brewing breaks, the storage should occur at 0 to 1o
c and the yeast kept
 In beer with some remaining extract or
 In beer with additional wort.
BEER QUALITY BEFORE FILTRATION

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After yeast removed the beer is moved from CCT to filtration. The beer at this stage should be
colloidal stable and should have the following properties;
 Temperature 0 to -1o
c ( after Lagering @-1 to -2.5o
c)
 CO2 content without carbonation at least 0.5%
 Ph 4.2 to 4.4, max- 4.6
 Yeast cell (population 1-2*106
)
 VDK content max- .1 mg/ml
 Oxygen content 0 gm/ml
BEER FILTRATION
The purpose of filtration is to make beer so stable that have no visible change occur for long
time. At the end of the maturation process the beer is oxygen free but up to 1*106
yeast cells and
other turbidity causing particles per ml are still contained in suspension, which have partially
removed without harmful oxygen having access to the beer ( by separator). Further filtered by
filter medium in to clear filtrate (beer) and a filtered residue, or filter cake which left behind.
Filtration methods
There are different methods of filtration:
- Separator mechanism
- Using filters

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- Using filter aids
BLENDING AND CARBONATION OF BEER
 Blending is a process of mixing dearated water with high gravity beer to obtain the
desired OG of low gravity beer. But addition of dearated water after filtration requires the
greatest care in order to guarantee highest quality. The dearated water that we use for
blending must satisfy many requirements. The water must
- Correspond in chemical composition (pH value, salt content) to that
used for beer production
- Be cooled -1o
c
- Be sterilized by sterilizer
- Be completely dearated
- Be carbonated to the CO2 content of the beer and,
- Be dosed in throughout the beer transfer.
 Carbonation is the process of replacing of the lost CO2 to standardized set point of the
company for keg and bottle beer. This is performed in carbonation plant when CO2 is
atomized and dissolved in the beer, in subsequent reaction path.
For quality reason, one must observe the highest purity level of the CO2, since the oxygen
which has now been introduced cause greatest damage of beer.
BEER STABILISATION

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Beer must be sold a long way away from it is produced, the stability of the beer for the duration
of sell by date (best before or maximum storage date) is very important.
Beer can become spoilt and unpleasant very quickly. There are several reasons for this:
 Any micro-organisms (contaminates) in the beer can multiply, make the beer hazy and as
result of excreting metabolic products, make it unpleasant.
 In time colloids in the beer increase in size, for various reasons, and make the beer hazy,
and
 With time the beer flavor becomes spoilt.
The brilliance of the beer is, along with its flavor and foam, an important evaluation factor which
every consumer can easily check without any aid within the sell by time. A beer drinker
considers a visible haze in the beer to be a serious quality defect. This can damage the image of
the beer and lead to a loss of customers. Therefore everything must be done to ensure stability
throughout the sell by period. There are two approaches to this, namely
 Making the beer microbial stable, and
 Making the beer colloidal stable.
As well as this, every effort must be made to maintain the flavor stability for as long as
possible.
MICROBIOLOGICAL STABILISATION OF BEER

PROCESS OF BREWING
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At the end of wort boiling the wort is sterile. Beer damaging micro-organisms can only get into
the beer as result of lack of cleanliness. They multiply in beer and produce metabolic products
which can make the beer completely undrinkable. If care is not taken, and if meticulously clean
working conditions are not used, haze and flavor changes can occur extremely rapidly- a few
days after days after filling. In extreme cases they can occur even during lagering. Therefore the
following applies always and everywhere in the brewery:
 The most important commandment in the brewery is” meticulously cleanliness
everywhere”.
The microbiological stability of beer is shortened
- By unclean operation
- By overloading the beer filtration plant
- By large difference between attenuation limit and final attenuation
(too short lagering or too green transfer)
- As a result of air introduction in to the beer, particularly during
filling,
- By warm storage,
- By continuous movement.
Of these factors the brewer can have most influence on cleanliness of working operation. This
must be a permanent operating principle. Micro-organisms can get into the beer from the
workforce staff and their clothing, or they are not removed as result of careless work (slacking).
Therefore must understand that the working environment should be clean.

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COLLOIDAL STABILIZATION OF BEER
Haze formation in beer due the factors:
 The storage temperature has without doubt the greatest influence on the haze formation
because an increase in temperature increases the rate of the reactions.
 Oxidation also has a very great effect on haze formation in beer. Extensive oxidation can
increase the rate of appearance of haze fivefold.
 Heavy metal ions greatly promote the formation of colloidal haze.
 Movement of the beer accelerates haze formation because of the more rapid coming
together of the colloids, and
 Light encourages oxidation and consequently haze formation.
Of all these factors the effect of oxygen is particularly detrimental to colloidal stability. It is
therefore advantageous always to prevent access of oxygen to beer.
Addition stabilizing agents
By observation the factors set out above, the formation of colloidal haze can be substantially
delayed but not prevented. Beer with a longer shelf life are therefore also stabilized by:
- Silica gel or Polyvinylpolypyrroilidone (PVPP)
- Antioxidants (Sulphur dioxide, ascorbic acid and sodium or
potassium metabisulphite)

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Silica gel – is an important stabilizing agent which binds the haze- forming
polypeptides but have little effect on foam promoting substances. They are applied in
amount of 50 to 150gm/hl and used before filtration.
PVPP- is a compound similar to protein, which can bind polyphenols to it. It is,
however, water soluble and therefore not permitted as a stabilizing agent. Only when
three-dimensional cross-linking in the form of pvpp occurs does it become insoluble
and can be used to bind polyphenols.
Antioxidants- beer flavor changes after filling as a result of an increase in the amount
of carbonyl compounds which promoted in particular by oxidation. By the addition of
substances which act against the oxidation (antioxidants), this process can be very
greatly retarded.
 Sulphur dioxide hinder the oxidation to form carbonyls therefore greatly
delays flavor ageing. SO2 in fact formed by yeast during fermentation but its
formation depends on yeast strain. The amount of formed SO2 is insufficient
for complete stabilization, but it does give a certain amount of protection
from ageing.
 Ascorbic acid, sodium/potassium metabisuphite – these have detrimental
effect for long time standing of beer flavor. Sometimes we can use sugar
reductones or glucose oxidase (in crown cork) can also be used.
 Tetra hope – this product prevents the formation of a light struck flavor. Its
addition is after filtration.

Brew manual.pdf

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Brew manual.pdf