This presentation describes how to make lager beer from harvesting of barley up to storage using a series of Unit operations and unit processes.

1. KYAMBOGO UNIVERSITY
FACULTY OF SCIENCE
BACHELOR OF SCIENCE IN CHEMICAL ENGINEERING
DEPARTMENT OF CHEMISTRY
CHE 315: MICRO-BIOLOGY PRESENTATION
Question6: Discuss in detail the steps in brewing of a lager beer, highlighting the micro-organisms used.
NAMES OF STUDENTS: REGISTRATION NO: SIGNATURE:
Opio Joshua Ochiba 14/U/138/CHD/GV
Kirembeka Joseph 14/U/134/CHD/GV
Gimei Benedict 14/U/132/CHD/GV
Barigye Edward 14/U/130/CHD/GV
Muyanja Derrick 14/U/6013/CHD/PD
SUBMITTED TO: MR. WACOO PAULALEX DATE: 11/10/2016

2. Brewing is the production of beer by
steeping a starch source (commonly
cereal grains, the most popular of which is
barley) in water and fermenting the
resulting sweet liquid with yeast.
 BARLEY – the body & soul of beer
 YEAST – the life of beer
 HOPS – the spice of beer
 WATER – the integrity & purity of beer

4. Malting is the process where barley grain is made ready
for brewing.
A. Selection of barley
B. Germination (Done by steeping)
C. Kilning
D. Milling
 Maximize Enzyme
Synthesis
 To Stabilize and Preserve
Enzyme Activity Well.

5.  Malt is sprouted barley. Barley is soaked in water to begin the process of
germination, then dried and toasted for flavor.
 Malting produces an enzyme, diastase, which turns starch into sugar.

6. • Two row barley (Mostly used)
• Six row Barley
 Germination is done by steeping the
barley in cold water at 10-200C for 2 or 3
days
 The Germination is accomplished by the
synthesis of myriad-enzymes.
 The barley reaches its maximum enzyme
activity when the rootlets reach a length
of one-third of the size of the grain.
 Barley is dried with a temperature
range of 45-600C to stop further
germination, stabilize and preserve
enzyme activity.
 Milling breaks the kernels apart and
exposes the cotyledon, which contains
starches, proteins and enzymes.

7. Mashing is the process of combining a mixture
of milled malt with water, and heating this
mixture in a vessel called a "mash tun".
 To activate the Malt Enzymes
 Naturally occurring enzymes convert starch
into fermentable sugars (Saccharification)

8.  The brewing water should have medium hardness
 The pH should be between 6 and 7.
 The mash (malt water mixture) is gradually heated
from 200C to 600C to 650C by infusion, decoction
or combination of the two, to extract as much sugar
as possible from the grain.

9. Lautering is the separation of the liquid containing
the sugar extracted during mashing from the
grains. The extracted liquid is the “wort”.
 The temperature of the mash is raised to
760C which effectively inactivates all
enzyme activity.
 The main component of wort other than
water is carbohydrate in form of small
fermentable sugars, the rest are carbohydrate
fractions of longer non-fermentable
oligosaccharides that include dextrins.
 The final PH of the wort is around 5.2.

10. In the final step prior to fermentation,
the wort is moved into a large tank
known as a brew kettle where it is
boiled with hops.
 Hops provide two (2) main
characteristics to beer
namely; flavour and
aroma.
 Hops also enhance
preservation and increase
shelf life of beer.

11.  1) It kills all the micro-organisms remaining after
mashing, making the wort, sterile.
 2) Inactivates most of the enzymes still after the mashing
or reduces their
activity to barely detectible levels.
 3) Enhances extraction of oils and resins from the hops and
accelerates isomerization of hop acids.
 4) Proteins, tannins, and other materials precipitate
during the boiling step.
 5) Enhances colour development by catalyzing formation
of Maillad reaction products.
 6) Undesirable volatile components such as Sulphur
containing aroma compounds are removed.
 7) Prolonged boiling causes evaporation of water and
concentration of the wort.

12.  The fermentation of the wort occurs in ferment
vessels of varying, size and configuration, and
in either batch or continuous modes.
 Lager fermentation vessels are typically
cylindric, with cone-shaped bottoms
(cylindroconical), so that when the yeasts
flocculate and settle, the cells collect within the
conical region.

13.  After the wort is cooled and aerated, the yeast
culture is, at last, added to the wort, in a step
called pitching.
 Lager beers are fermented by Saccharomyces
pastorianus also known as the “lager” or
“bottom-fermenting” yeast.
 In contrast, when lager yeasts flocculate, the
flocks sediment to the bottom.
 Larger style beers are fermented by yeast capable
of growing at temperatures below 150C.
LAGER!!

14.  For lager beers, Conditioning or
lagering occurs in tanks held at
lower temperatures for a longer
time.
 Typically, temperatures as low as
00C, for as long as three months,
can be used.
 Lagering matures the beer &
mallows its flavour.
 The CO2 that evolves is trapped,
and the beer becomes naturally
carbonated.

15.  After conditioning by lagering, clarification is
done to remove any suspended yeast cells and
other micro-organisms that are still be present.
 Clarification can occur via physical separation
methods such as centrifugation or by addition of
fining agents.
 Fining agents act by promoting flocculation of
yeast cells and include wood chips, gelatin, and
isin glass.
 Several filtration configurations exist including
plate and frame systems, leaf filters, cartridge
filters and membrane filtration.

16.  Carbonation provides sensual appeal by
enhancing mouth feel, flavour, body and
form.
 Carbondioxide preserves the beer by
reducing the PH and the redox potential
such that various aerobic, acid sensitive
spoilage organisms are inhibited.
 Carbonation of beer can occur naturally via
secondary fermentation or mechanically by
directly adding carbondioxide after the
condition and clarification steps.

17.  The simplest form of packaging is to feel the beer directly into
cans or glass bottles. The packaging steps are performed under
aseptic conditions to prevent post processing contamination.
 Sterile nitrogen or carbondioxide can be used to flash the
environment and sterile water used to ensure that the relevant
equipments, especially the areas around the fillers remain free of
microbial contaminants.
 After packaging, beer is heat pasteurized. Lager beer is always
processed via tunnel pasteurization systems in which filled and
sealed bottles or cans are heated by hot water.
 Pasteurizing the beer after it is already in sealed packages prevents
post pasteurization contamination.

18. ANY QUESTIONS ??
Drink & Serve Responsibly
THE END!!!