The University of Mauritius (UOM) is situated at Reduit, Moka. It comprises of the following faculties: agriculture, science, law and management, social studies and humanities and engineering. This power point presentation was made by a group of students from the faculty of agriculture; doing the course BSc (Hons) Biotechnology.

1. BEER FERMENTATION
Presented by Biotech Year 2
students from UOM:
Bamma Leckrani
Huët Laetitia
Golamaully Sadaf
Gooskhan Naseerah
Jahally Faatimah

2. Table of contents
 Beer definition
 History of beer
 Composition of beer
 Brewery process
 Types of beer
 Difference between ale and lager
 Factors affecting Beer Quality
 Top companies involved in beer production
 Worldwide impact of Brewing industry
 Benefits and Downsides of Beer Consumption
 References 2

3. What is beer?
 Name comes from bibere; a
latin word, meaning “to
drink”
 Is an alcoholic fermented
drink
 Consists of malted grains
(wheat, barley...)
 Uses yeast as microorganisms
in fermentation process
 Different carbohydrate
sources create different beer
styles and flavors.
Figure 1: Different grains used give
different beer styles.
3

4. History of beer
 4000BC – In the middle east, the Sumer people were fermenting a form of bread to
make a fermented pulp which had an intoxicating effect.
 3000BC –The early beer was cloudy and unfiltered and was usually drunk through a
straw to avoid drinking the solids from the brew, which could be very bitter.
 1550BC – The Egyptians were also keen brewers. Beer and malt have been found
buried in the tombs of the Pharaohs to provide sustenance for the afterlife.
 100AD – Beer was extensively drunk throughout the Roman Empire. Beer from this time
had to be consumed fresh and it was served cloudy. In addition, the beer would have
produced little or no foam at all. To aid its taste and keeping properties, bitter herbs
and spices may have been used.
Figure 2: Babylonians
drinking beer with straws.
Figure 3: Hieroglyphics
showing presence of
beer in Egypt.4

5. History of beer
 The Middle Ages – The largest brewers were the monasteries.
 From 1000AD – Most beer was bittered with wild herbs.
 From 1150AD – The addition of hops slowly spread throughout Europe reaching Britain by the
middle of the 15th century.
 The Reinheitsgebot (German Purity Law) of 1516 – The law stipulated that beer could only
be brewed from water, hops and malt and that the use of yeast would come later, after it had
been identified as the organism responsible for fermentation.
 The Free Mash Tun Act of 1880 - The new law enabled "the brewer to brew from what he
pleases and have a perfect choice of his materials and methods".
 In 1882-1895 - Louis Pasteur, a French scientist, discovered that there were different types of
yeasts that could be used in different types of fermentation hence producing distinct beer
flavours.
 Today - beer occupies the 1st ranking order in terms of the mostly consumed alcoholic drink
around the world.
Figure 4: Beer brewing
in monasteries.
Figure 5: Medieval
Brewery.
5

6. Compositions
 Water
 Malt
 Hops
 Yeasts
Figure 6: Basic ingredients of beer.
6

7. Water
● Makes up 90% of volume of beer.
● Is obtained from well or spring or tap water might also be
used.
● Its purity is maintained to obtain good beer.
● Its salts and minerals contents is monitored and adjusted.
I. If water contains too much of sulphur, the brew becomes
bitter.
II. Magnesium on the other hand is an important molecule for
yeasts.
7

8. Malt
Figure 7: Malt extract used can be
in the dried or liquid form.
● Sugar coming from malted grains such as barley, wheat,
oats, maize and rice.
● Soaking of grains in water allow germination and
enzymes’ activation.
● Conversion of starch and proteins into sugars and amino
acids.(malting)
● Heat drying of grains to deactivate enzymes.
● Crushing and soaking of malted grains in hot water to
reactivate enzymes.
● Enzymes produce maltose sugar which is boiled with hops
and yeasts to produce beer.
8

9. Hops
Figure 8.1: Hops.
Figure 8.2: Waxy yellow lupulin gland
within leaves of the flower.
● Are cone-like flowers obtained from the Hop vine plant.
● Grows in regions like North America, Europe and Asia.
● Humulones found in lupulin:
I. Gives the beer its bitterness.
II. Increases the beer’s shelf life.
● Hops contains resins and oils.
I. The resins gives bitterness to the beer.
II. The oils enhances the flavour and aroma of the beer.
9

10. Yeasts
 Are unicellular microorganisms.
 Convert sugars into alcohol and carbon dioxide.
 Are added after water and malt altogether is
boiled and cooled.
 Two types of yeasts are usually used:
I. Ale yeast (Saccharomyces cerevisiae)
II. Lager yeast (Saccharomyces uvarum)
Figure 9: Yeasts.
10

11. Other ingredients used:
Figure 13: Fruits and vegetables.Figure 12: Spices.
Figure 10 : Unmalted grains. Figure 11 : Other sugar sources.
11

12. 1. Malting
2. Milling
3. Mashing
4. Lautering
5. Boiling
6. Hop
separation
and cooling
7. Fermentation
8. Lagering
9. Bottling and
preservation
12

13. 1. Malting
 The grains are soaked in water tanks for 2-3 days at 10-15°C (steeping)
 They are allowed to germinate for 6-15 days(humidity: 45%, temperature:
12-21°C).
 Enzyme cystase converts insoluble starch to soluble one.
 Enzyme diastase converts the soluble starch into sugars.
 Conversion of starch into sugars (maltose) is known as malting.
Figure 14: The malting process in barley.
13

14.  The malt is then hot air dried at about 55⁰C in oast houses (oasting).
Figure 15.1: The structure of an oast
house.
Figure 15.2: The cross section of the oast
house.
14

15. 2. Milling
 After drying and heating, the rootlets from the malt is removed.
 These malt culms are then sold to provide feed for cattle.
 The grains are then grinded coarsely in roller mills; forming grists.
Figure 16.1: The roller
mill.
Figure 16.2: Different varieties of
grinded malted grains.15

16. 3. Mashing
 The grist is mixed with hot water
 The mash is cooked for up to 6
hours at low temperature.
 Enzymes in the malt convert
starch into sugars producing wort.
 The wort is then boiled for about
an hour and a half.
 Factors like: temperature, time
and pH are adjusted. Figure 17: The mash tun.
16

17. 4. Lautering
 Refers to the separation of wort(sugar
solution) from the undissolved part of the
grain.
 Water is sparged through the grains.
 Sparging must be done very gradually.
 This process is done in tanks known as
lauter tun which contains a giant sieve.
 The spent grains are sold as feed for cattle.
 The malt mixture might also be sprayed
with hot water.
Figure 18: The lauter tun.17

18. 5. Boiling
 The wort is then transferred into boiling tanks
(kettle)
 Hops are added at this stage.
 Boiling :sterilizes the wort, inactivates enzymes,
coagulates proteins present and forms flavour
compounds from added hops.
 Hops and precipitated proteins are separated from
wort after boiling is done.
 Resulting liquid is cooled in a plate heat exchanger
to the fermenting temperature.
Figure 19: The copper kettle.
18

19. 6. Hop Separation and Cooling
 Proteins and hops are then removed from the wort.
 The wort is oxygenated during cooling.
 The wort then goes to the hot wort tank.
 It is then cooled in a plate cooler where the
coolant flow in opposite direction to the wort.
 The wort’s temperature drops from boiling to
about 10-20°C in a few seconds.
Figure 20: The plate cooler.
19

20. 7. Fermentation
 The cooled oxygenated wort is placed into
fermenting vessels and yeasts are added.
 Vessels used: square open or conical(mostly used).
 Fermentation last for about 7 to 10 days or more.
 The function of the fermenter is:
 To contain a maximum amount of wort.
 To allow evacuation or collection of carbon dioxide.
 To have a proper cooling system.
 To monitor pH and pressure inside vessel.
20

21. Fermenter tanks
 The open square vessel:
 Older types of vessels originally made of slabs.
 Modern one-stainless steel.
 Supports top fermentation.
 Internal cooling pipes present.
 Liquid pumped from bottom to top- mixing of
wort with yeast and for aeration purposes.
 Accumulated liquid flow through organ pipes
to bottom.
 Yeasts easily removed from tray at the end.
Figure 21: The open square fermenter.
21

22. Fermenter tanks (cont.)
 Cylindro-conical vessels:
 Large stainless vessels- industrial use.
 Yeasts and wort pumped through bottom of
vessel-reduce admission of O₂.
 Mostly supports bottom fermentation.
 Vessels equipped with cooling jackets and
pressure relief valves.
 CIP fluids introduced through vessel by a CIP
arm.
 Yeast is collected at bottom in the cone which
can be cleaned easily.
CIP spray
ball
Figure 22: The cylindro-conical vessel.
22

23. Fermentation
 Fermenting temperature depends on yeasts being used.
 Antifoam agents used when foam production is high.
 At the end of the fermentation, the yeast is removed and saved for reuse in the
next batch.
 Four main factors affecting the rate and quality of beer fermentation:
1. Fermentation temperature.
2. Volume of yeast used at the start of fermentation.
3. Volume of oxygen in the wort at the start and during fermentation.
4. Level of nutrients in wort. 23

24. Four Stages of Beer Fermentation
1. Lag Stage
This stage take a half to 2 days depending on:
 Yeast pitching rate - refers to the amount of
yeast that is added to cooled wort.
 Yeast viability - refers to the percentage of
viable cell in a population.
 Yeast vitality - refers to the activity or
metabolism of the cell.
 Wort temperature
 Wort aeration rate before the fermentation
start.
 The yeast adaptation time.
Graph 1: Stages in beer fermentation.
24

25. Four Stages of Beer Fermentation (cont.)
2. Log (Accelerating) Stage
 Yeast cells and beer temperature increases up to the maximum.
 Beer is cooled to keep temperature constant all the time.
 Foam is seen on surface of beer.
3. Stationary stage
 Beer gravity will drop.
 Foam becomes dark.
4. Declining Stage
 Beer fermentation rate and fermentable sugar in the beer decreases.
 Beer temperature is cooled down.
25

26. Summary of the processes that occur during
fermentation.
I. Yeasts use up O₂ producing sterol promoting its growth.
II. The pH is reduced and ethanol and CO₂ are formed.
III. When most of the wort sugars are used up, fermentation
rate decreases.
IV. An increase in alcohol level causes flocculation and
settling of yeasts.
V. Beer is removed and subjected to further treatment.
26

27. Types of Beer fermentation
1. Top
fermentation
2. Bottom
fermentation
 Use ale or ‘top-
fermenting’ yeast
Saccharomyces cerevisiae
 Warmer temp: 65 – 75oF
 Yeast and foam found at
the top of the medium is
removed
 Second crop that is
produced by the end of
fermentation is
harvested since the yeast
is pure.
 Types of beer produced:
Ale, porter, stout…
 Use lager or ‘bottom-
fermenting’ yeast
Saccharomyces uvarum
 Cooler temp: 45 – 55oF
 Settled yeast is
decanted from the
unconditioned beer.
 It is manually collected
from middle layer of
the sediment due to its
purity.
 Types of beer produced:
Lager, pilsner…
27

28. Other beer fermentations types
3. Spontaneous fermentation
 Uses wild yeasts from air : Brettanomyces bruxellensis and Brettanomyces lambicus.
 Lactic acid and acetic acid fermentation gives the beer a sour taste.
 Beers produced: lambic, geuze, kriek and faro.
4. Mixed fermentation
 Yeasts similar to top fermentation is used.
 Bacteria are also used.
 Combination of spontaneous and top fermentation.
 Conversion of organic acids and higher alcohols to esters.
 Aging of some beers to develop fruity flavour.
28

29. Fermentation systems used in beer production
1. Batch fermentation system
 Bioreactor is loaded with fresh medium and the selected yeast strain.
 During growth period, no medium is added or removed.
 Entire medium is removed from the vessel at the end of fermentation.
 Vessel is cleaned and the new batch is started.
2. Fed batch fermentation system
 Wort is continuously added in the vessel as soon as they are being
used up.
 Beer is removed when production reaches maximum.
29

30. Fermentation systems used in beer production
3. Continuous fermentation system
 Used in large scale production of beer.
 Wort is continuously supplied and the product is being removed at the
same time.
 Disadvantages:
 Microbial contamination is more
recurrent.
 Costly vessels are used.
 May not be suitable for all beer
qualities.
 Advantages:
• Rapid conversion of wort to beer.
• Higher efficiency; high ethanol yield is
observed.
• It is more economical.
30

31. 8. Lagering
 Lagering- storing and conditioning stage of beer.
 Beer is kept at about 0°C in stainless steel tanks after
fermentation has occurred.
 Beer is stabilised and matured to produce desired
flavour.
 It is either pasteurised or filtered once or twice before
bottling.
 This process takes 1-3 weeks or months depending on
the type of beer being produced.
Figure 23: The lager tank.
31

32. 9. Bottling and preservation
 Packaging done in: bottles, cans and barrels.
 The container is kept free of oxygen.
 The beer is then pasteurized.
 This kill the remaining yeasts.
 Beer can also be preserved using special micro-
filters.
 When bottling, the beer is also subjected to
carbonization process. Figure 24: The bottling process.
32

33. Types of beer
 Generally, beers are classified according to the type of yeasts used in the
fermentation process.
Beer
Ale
Pale ale Mild ale Stout
Lager
Light
lager
Dark
lager
33

34. Ale beer Lager beer
Antique type of beer Relatively new concept
Top fermentation Bottom fermentation
Saccharomyces cerevisiae is used Saccharomyces uvarum is used
Brewing occurs at 65-75°F Brewing occurs at 45-55°F
Quick brew cycle (7 days) Longer brew cycle (several months)
Served cool at 10-14°C Served cold at 4-7°C
Has a relatively shorter storage period Has a longer storage period
Darker brown colour Bright gold to yellow in colour
Strong taste Subtle taste
Higher alcohol content Lower alcohol content
Lower carbonation Has high carbonation
Styles: pale ale, porter, amber ale,
stout, brown ale, strong ale, wheat
beers, speciality ale
Styles: pale lager, dark lager, bock beer,
amber lager, speciality lager, malt liquor,
steam beer
Differences between ale and lager beers
34

35. Factors Affecting Beer Quality
 Activity of yeast cell during fermentation influence character of beer.
 Factors affecting quality of beer produced:
 Non-fermentable components - have an impact on the medium.
 Fermentable sugar - converted also to some.
 Inner yeast cell released components - released from the yeast cell when
it is inactive.
 Surface active components - adsorbed into the yeast cell wall.
 Contamination – has huge impact on fermentation.
35

36. Top 10 companies involved in beer production
Rank Companies Country
Beer output
2014 in mill.
hl
Share of world
beer production
1
Anheuser-Busch
InBev
Belgium 411.5 21.0%
2 SABMiller UK 187.8 9.6%
3 Heineken Netherlands 181.3 9.3%
4 Carlsberg Denmark 122.8 6.3%
5
China Resource
Snow Breweries
China 118.4 6.0%
6
Tsingtao Brewery
Group
China 76.2 3.9%
7 Molson-Coors USA/Canada 59.0 3.0%
8 Yanjing China 53.1 2.7%
9 Kirin Japan 46.6 2.4%
10 BGI/Groupe Castel France 31.7 1.6%
Sources: Barth reports 2014-2015 36

37. Worldwide Impact of Brewing Industry
 Global consumption of beer - increased significantly these last 10 years.
 In US only, more than 424,000 jobs, with more than 115,000 jobs directly at
breweries and brewpubs are provided.
 Scientific claiming: the price of beer is likely to rise due to climate change
that affect production of grains.
Note: Both analysis were obtained from this site: https://www.surveymonkey.com/blog/2014/05/01/
37

38. Benefits and Downsides of Beer Consumption
Benefits
 Provides vitamins, minerals,
and flavonoids.
 Lowers risk of coronary heart
disease (CHD).
 Helps produce good cholesterol.
 Reduces risk of kidney stones.
 Reduces sensitivity to Insulin.
 Strengthens the immune
system.
 No significant relationship with
weight gain and beer
consumption.
Downsides
 Impairment of driving-related
skills and slow reaction time.
 Damage of organs and increase
risk of cancer.
 Withdrawal symptoms.
 Heartburn.
 High blood pressure.
 Intoxication and dehydration.
38

39. References
 http://www.todayifoundout.com/index.php/2013/10/can-brew-
beer-stomach/(21.09.15)
 http://www.bierengezondheid.be/index.php/articles/en/cid=5/aid=
73/?PHPSESSID=ff2266800a7c066bd6ad258ca08ba175(21.09.15)
 http://www.thebeerstore.ca/beer-101(21.09.15)
 http://www.thekitchn.com/the-ingredients-you-need-to-brew-beer-
and-where-to-get-them-the-kitchns-beer-school-2015-
217249(21.09.15)
 http://www.howtobrew.com/section1/chapter5.html(22.09.15)
 http://independentbeers.com/2013/09/how-to-make-
beer/(22.09.15)
 https://www.midwestsupplies.com/differences-ale-lager-
yeast.html(23.09.15)
 http://alexander-beer.co.il/?page_id=439(23.09.15)
 http://www.livestrong.com/article/389075-beer-drinking-related-
health-problems/(23.09.15)
 http://www.barthhaasgroup.com/images/pdfs/reports/2015/BarthR
eport_2014-2015_EN.pdf(23.09.15)
 https://www.wyeastlab.com/he_b_fermentation.cfm(24.09.15)
 Encyclopedia of Food Microbiology(20.09.15)
 http://www.sterkensbrew.be/sbm/beer_making.html(20.09.15)
 http://anthonymartin.be/en/news-events/news/79-the-health-
benefits-of-beer-12-reasons-why-you-should-drink-it/# (20.09.15)
 http://sciencebrewer.com/2012/08/06/experiment-effects-of-
fermentation-temperature-on-beer/ (19.09.15)
 http://www.virtual-labs.leeds.ac.uk/brewing/vessels.php(2.10.15)
 http://anthonymartin.be/en/news-events/news/31-high-or-low-
different-fermentation-styles-for-different-tastes/(24.09.15)
 http://www.beer-
brewing.com/beer_brewing/beer_fermentations/yeast_collection.ht
m(24.09.15)
 http://www.craftbrewingbusiness.com/equipment-systems/brewing-
vessels-reviewed-cylindroconical-fermenters/(2.10.15)
 http://www.daltraining.eu/WebHelp/006_Fermentation_practice/6.
1.2._Fermenters.htm(22.09.15)
 http://www.aperfectpint.net/What%20is%20Beer%20-
%20The%20Basics.pdf (19.09.15)
39

40. THE END
CHEERS