Beer production

Introduction and Microbial
Production of Beer Prepared by:
Othima Sharma
M.Sc. Biotechnology 2nd Semester
Roll: 301101023

History
Chemical analysis of 7,000 year-old jugs puts
invention of beer around the same time period
as wine
Addition of hops to beer occurred about one
thousand years ago but before the 14th century
spruce, ginger, wormwood, sage, and sweet
mary were more popular.
1516 Bavarian purity law passed, oldest
known food purity law still in effect, limited
ingredients of beer to hops, barley, and water.
16th century lager beer type accidentally
invented during cold cave fermentation.

Essential Ingredients of Beer
• Malted Barley
• Hops
• Yeast
• Water
• Not required, but frequently found ingredient
− Starch adjuncts
• Corn and rice starches

Yeast
It is usual to select
strains of yeast for
brewing from yeasts
already in commercial
use.
Some breweries isolate,
select and maintain
their yeast strains but
others engage
specialist laboratories
to provide this service.

Yeast can be found naturally on the surface of
most plants including barley seeds.
“Wild” yeast will most likely produce flavors that are
undesirable.
During the fermentation process, undesirable
microbes must be kept out of the beer.
Saccharomyces cervisiae is the species most often used for ales, its optimum
fermentation temperature is 16-24 C

Saccharomyces uvarium is largely used in lagers, and steam beers. The
optimum temperature for this fermentation is 2-13 C

Over a 15 square mile area near Brussels the resident wild
yeast and bacterial populations are perfect for spontaneously
fermenting, beer. This fruity sour beer is known as a “lambic”.

What qualities should my yeast have?
Rapid initiation of fermentation
High fermentation efficiency
High ethanol tolerance
Desired flavor characteristics
High genetic stability
Range of alcohol production

Yeast Inoculum
In the average
brewery, a large
inoculum of cells is
used (ca 5-15
million cells/ml of
wort).
In each fermentation
the cell density
increases three-to-
four-fold.
Therefore, one-third

Metabolism
Major Reaction: Glucose to Carbon Dioxide and Ethanol

Special flavors and aromas of beers arise from minor biochemical reactions

Malt
Malt is one of the main
ingredients and is obtained
from barley, which is
subjected to a process of
germination under
controlled conditions. This
operation (called malting)
causes, towards the end of
the production process, the
development of
carbohydrates and
nitrogenous substances by
the enzymes formed during

Other unmalted cereals
Of the unmalted
cereals normally
used, corn is very
common; the oils are
extracted, then it is
milled and called grits.
Barley, rice or wheat
may also be used.
These cereals are
used to reduce the
percentage of proteins

Hops are the flowering portion of the
hop vine.
These flowers not only fight off
bacterial infections in the beer, they aid
in clarification of the beer, stabilize the
Hop oils are produced in the Lupulin
flavor, help retain head, and aid in ones
glands of the flower.
ability to drink the beer.
The oils are made of α and β-acids, but
α-acids contributes more to the bittering
of a beer.
These oils are non-polar, and can only
be extracted through a short boiling.

Hops (humulus lupulos):
Why it is Used??
The hop (humulus
lupulos) is an aromatic
plant that gives beer its
flavour and bitterness. It
contributes to the
formation of a good froth
and protects the beer
against contamination by
microorganisms. Today,
extracts from this plant
are used industrially,

Wort

• What’s in it:
−Brewers' wort (145) commonly has 8-14%
total solids.
−90-92% are carbohydrates:
glucose, fructose, maltose, sucrose, malto
triose.
−Nitrogenous compounds, such as, amino
acids.
−Vitamins: biotin, inositol, pantothenic

Preparing the Wort

The first phase in the process of
beer production is the preparation
of the wort.

Milling
Mashing
Filtration of the
wort
Boiling the wort

Milling: Mashing: The flour from the
In order
for the cereals (malt and other
malt unmalted cereals) is mixed
compone with water and subjected to
nts to be
rapidly certain processes to obtain a
extracted wort of a suitable composition
and
converted for the kind of beer being
, the malt produced (varying
is milled times, temperatures and PH).
to obtain
coarse These conditions encourage
flour. The the development of complex
other
unmalted starch molecules and proteins

Filtration of the wort: After mashing, the
whole volume is filtered in order to separate
the spent grains (which is an excellent
animal feed) from the wort itself. This is
done by passing water through the mash at
the right temperature in a filter press or
lauter tun, which lasts around 2-3 hours,
conducted at a temperature of 75-80 ºC.

Boiling the wort: The diluted and filtered
wort is boiled for around 2 hours. Hops are
added at this stage. The purpose of boiling is
to:
Transform and make soluble the bitter
substances in the hops;
Eliminate undesirable volatile substances;
Sterilise the wort;
Provoke the precipitation of proteins of
high molecular weight;
Establish the final concentration of wort.
After boiling, it is necessary to separate the

Fermentation/Maturation/Stabilisation

During fermentation, the wort sugars are
converted by the transformation of yeast into
alcohol and carbon dioxide. Fermentation
begins when yeast of a culture selected for the
type of beer being produced is added to the
cooled oxygen-saturated wort.
Fermentation takes place at controlled

Maturation, The next
the phase after operation is
fermentation, is stabilisati
the period in on. This
which the beer is consists of
allowed to rest letting the
at suitable beer
temperatures in stabilise at
order for the temperatur
undesirable es of

Clarification of the Beer

Clarification is the operation that
gives the beer its clear limpid
quality, eliminating the last remaining
traces of clouding still in suspension.
It consists of pumping the liquid

Bottling

The final stage of the beer production
process is transferring the beer into
different kinds of containers
(bottles, barrels, cans etc).
Before or after bottling, the beer needs to
be biologically stabilised. This operation
may be carried out cold (sterilising
filtration) or hot (using
pasteurisation, which may be done either

Beer
Production
Process:
At A Glance

Process

Malted Barley
and
Specialty Grains

Malted barley and specialty grains are run
through roller mill and cracked open.
This grist is then carried by an auger to the

Process

In the mash tun the grist is mixed with hot water to
form a mash.
In the mash, enzymes that exist in the grain become
active and convert the starches to fermentable sugar.
The sugar rich liquid from the mash, called wort, is

Process

The wort is drained from the mash tun and
moved to the brew kettle.
In the brew kettle the wort is boiled and hops
are added.

Process

After boiling, the wort is transferred through a
chiller.
While passing through the chiller the wort is
instantly chilled to the appropriate temperature

Process

From the chiller, the wort moves into a
temperature controlled fermenter.
Yeast is added and fermentation begins. In
fermentation the yeast will ferment sugars in the

Saccharomyces cervisiae Saccharomyces uvarium
Location of fermentation Top Bottom
Risk of infection High Low
Fermentation Time Short Long
Metabolizes Ethanol, Sugars Glyceraldehyde, Melibiose, Sugars
Fermentation Temperature 16-22 C 8-16 C

Fermentation Systems
• Cylindroconical systems:
−Produce ales and lagers.
−Conical base, and pressure systems.

• Open systems:
−Used for the
fermentation of ales
−Utilize skiming for
repitching
−Carbon dioxide can

Types of Beer
(on the basis of fermentation conditions)

Ales & Lagers

Fermentation of Ales
Top fermenting-rise to the surface
and create a think yeasty head.
Warmer temps- 60-70F
More rapid growth
Create more esters
Complex and Fruity
Ales, porters, stouts, and wheat
beers.

Fermentation of Ales
Lag phase is when yeast is building cell
walls and reserves.
Then yeast begin to divide.
First visible sign of fermentation is
bubbles starting to form, which spread
until the surface is covered.
After 18 hours the bubbles thicken and
change to a light brown color.
pH and specific gravity fall, and
temperature and yeast count rise.
Max fermentation is reached after 36-48
hrs.
White yeast head on top, with CO2

Fermentation of Lager
Bottom fermenting-yeast
settle to the bottom of the
fermenter as fermentation
reaches completion.
Colder tempeatures: 47-58F
Slower growth
Crisp and hoppy like a
pilsner or sweet and malty
like a Dopplebock.
Examples: Pilsners, Bocks,

Fermentation of Lager

Time-temperature profiles vary widely.
Pitch the yeast at 5-60 C and raise to 8-
90 C. This makes better beer because
the low temps retard the development of
by-products which are inappropriate in
lager (esters, fusel alcohols, diacetyl).
Lag period is longer at lower
temperatures though.
After primary fermentation the
temperature is dropped by 1-1.5C each

Compounds produced in primary fermentation
and not reduced during lagering

• Fuel or higher alcohols:
 By-product of amino acid metabolism.
 Levels are affected by yeast strain.
 Spicy, wine-like, and alcoholic taste.

• Organic acids:
 Formed from carbohydrate metabolism
 Contribute to the sourness or acid taste
(also pH) of beer.

Esters:
By-product of lipid metabolism in a
reaction between an alcohol and
intermediates of lipid synthesis.
Acetate esters Fatty acid
Usually impart a fruity character to the
beer. ester
 There areethyl acetate ethyl
two types: (solventy, caproate
Ale yeast strains sweet)
fruity, (apple,
isoamyl aniseed,
produce acetate sweet)
more esters

Compounds produced in primary fermentation
and reduced during lagering
• Diacetyl
 Byproduct of amino acid metabolism.
 Tastes like butter, butterscotch, and
feels slick on the palate.

• Pentadione
 Similar to diacetyl.
 Milder flavor similar to honey or butter.

Acetaldehyde
Intermediate of ethanol production.
It can form in autolysis of yeast during
lagering if yeast is in poor condition.
It can also form if post-fermentation beer is
exposed to air (oxygen).
Ethanol can be oxidized to acetaldehyde.
Acetoin
Formed from a secondary reaction of
alcoholic fermentation.
Pyruvate decarboxylase converts pyruvate
to acetaldehyde, which is then converted to

Process

After fermentation the fermented wort, now called beer, is
transferred through a filter.

The filter removes various proteins, hop residue and yeast cells.

Process

From the filter, the beer moves to the beer servers.

These are carbonating tanks, holding tanks and serving tanks.

Making Beer:
a three step process

Malting
Brewing
Fermentation

Malting
• Takes place in malt houses
− Occasionally in a brewery (Coors)
• Controlled germination of barley
− Moisture
− Temperature
− Carbon dioxide
• Goal
− Produce enzymes useful for brewing
• Amylases
• proteases

Malting
• Soaking the grain
• Allow for controlled
germination
− Maximum enzyme
production
− Minimum enzymatic
activity and plant
growth
• Kiln drying
− Stop germination
− Stabilize malted barley
− Impart color and flavor
• Light malt, dark

Brewing
• Functions:
− Enzymatic conversion of starch to maltose, proteins
to amino acids
− Extraction of hop flavors and aromatic compounds
− Sterilize maltose/aa/hop flavor solution

Brewing
• Milling of malted barley
− Careful cracking of malted barley
• Shatter endosperm
• Keep husk in large pieces

• Adding water
• Controlled temperature for enzymatic action

Mash Tun

The mash tun is a vessel in which the milled malted
barley is mixed with water And the enzymes are
allowed to degrade the starches and proteins into

Mash

These photos show the milled
Malted barley being mixed with
Warm water. The enzymes
Convert the starch to maltose and
The proteins to amino acids creating
What is known as sweet wort.

Lautering
(filtering)
The sweet wort
Is separted from
The spent barley
By a filtration step
Known as
Lautering. The
Barley husks serve
As the primary
Filtering material.
Here, the remaining
Spent grains are
Being removed from
The sweet wort
With this screen.

Mash Tun with used
Mash
These are the
spent malt that
acted as a
filtering bed for
the sweet wort.

Used mash heading
towards feedlot

Kettle
• Sweet Wort
• Bring to boil
− Add hops
• Extract flavors
(bitter acids) and
aromatic
compounds
− Sterilizes hopped wort

Fermentation Tanks
After the yeast is
added to the
hopped wort,
fermentation of
the maltose to
Ethanol occurs in
these tanks.

fermentation tanks
Fermentation produces
both ethanol and carbon
dioxide. The
carbondioxide is
allowed to vent out
through these blow-off
hoses whose ends are
immersed in a tank of
water, producing an air-
lock and preventing
Oxygen from entering
the fermentation tanks.

Cleaning fermentation
tanks
Cleanliness is
critical in
producing
Quality beer.
Microbial
contamination
Can result in off
flavors and aromas.

Raw Materials Preparation Transformation

Mashing
Barley

Water
Filtration
Boiling

Hops

Cooling
Carbon
Dioxide
Fermentation
and Yeast
Yeast Maturation

Bottling
Clarification

Mill Fermentation

Mashing Clarification

Filtration Bottling

Wort Boiling Wort Production

Beer production

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