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Art ofbrewing
1. The Art of Brewing
and
The Biology of Lager Yeast
Tom Pugh
Miller Brewing Company
2. Purpose
• Provide a better understanding of...
– The brewing process
– Types of brewing yeasts
– Attributes important to the brewer
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
3. The Art of Brewing
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
4. Definition of Beer
• An alcoholic beverage produced by the
fermentation of sugar-rich extracts derived
from cereal grains or other starchy
materials.
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
5. History of Brewing
• Man has been making beer since the dawn of
civilization.
– Where grain was grown, beer was made.
• Sumaria (4000 BC) Sikaru
• Egypt (3000 BC) Zythum
• India (2000 BC) Sura
• China (2000 BC) Kiu
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
6. History of Brewing
• Sumarian beer recipe
– 3000 BC
• Resembled liquid bread:
– Barley and Emmer
– Spices / fruits
– No Hops
• Safe, nutritious, and
exhilarating beverage.
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
7. The Role of Yeast in Brewing
• Unwittingly, ancient brewers domesticated yeast.
– Selected yeast that made good beer.
• Deduced that yeast was important to make beer.
– Collect the creamy foam or sediment from one brew.
– Use it to pitch the next brew.
Did not know what yeast was.
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
8. The Role of Yeast in Brewing
• 1680 Antonie van Leeuwenhoek
– Observed yeast in beer.
• 1837 - Cagniard Latour
– Microbe is responsible for alcoholic fermentation.
• 1839 -Justus von Liebig and Friedrich Wohler
– Alcohol is produced by a chemical process in which dead and
decaying yeast participated.
– Satired Latour’s theory in Annalen der Chemie . . .
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
9. ….small animal which sips sugar through its snout, and
excretes alcohol from its gut and carbonic acid from its
urinary organ.
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
10. The Role of Yeast in Brewing
• 1866 - Louis Pasteur
– Yeast was responsible for alcoholic
fermentation.
• 1883 - Emil Christian Hansen
– Developed pure culture technique
– Isolated pure cultures of brewing yeasts
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
12. Types of Brewing Yeasts
• Two types of brewing yeasts, originally classified
on flocculation behavior…
• Top-fermenting
– Ale yeast
– Weiss yeast
• Bottom-fermenting
– Lager yeast
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
14. Ale Yeast
• Predominant brewing yeast prior to the mid-1800s.
– Displaced by lager yeast
• Strains are genetically more diverse - several origins
• Warm fermentation temperatures: 65 to 72 °F.
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
15. Weiss Yeast
• Bavarian origins - closely related.
• Produces beer that has spicy, clove, vanilla, and
nutmeg flavor notes - POF.
– PAD1 gene phenylacrylic acid decarboxylase
– Decarboxylation of ferulic acid forms 4-vinyl-guaiacol,
which gives the characteristic clove flavor.
• Warm fermentation temperatures: 65 to 72 °F.
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
16. Lager Yeast
• Bavarian origin.
– 1400s in Munich - cool fermentations (selective pressure)
– Taken to Pilsen and Copenhagen in 1840s
• Pale malt, soft water, aromatic hops
• Became very popular - displaced ale yeast
• Popularity fueled by advances of Industrial Revolution
– Steam power, refrigeration, railroads, pasteurization and
filtration technology
• Strains are closely related - common origins
• Cool fermentation temperatures: 42 to 52 °F
• Beers are more delicate, clean, drinkable, and less
aromatic.
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
17. Taxonomy
• Ale and Weiss yeasts - Saccharomyces cerevisiae
– Polyploid and probably aneuploid.
– Non-mating
– Sporulates poorly and poor spore viability
• Lager yeast - Saccharomyces pastorianus
– S. cerevisiae
– S. carlsbergensis
– S. uvarum
– Sporulates very poorly - poor spore viability
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
18. Distinguishing Characteristics
• Colony morphology
• Microscopic appearance
– Chain formation
• Fermentation characteristics
– Flocculation behavior / flavor compound profiles
• Growth at 37 °C
• Melibiase
• Electrophoretic karyotyping
Yeast 37 °C Melibiase POF
Lager - + -
Ale + - -
Weiss + - +
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
19. Distinguishing Characteristics
• Difficult to distinguish between different lager yeasts
using conventional techniques
– Colony and cell morphologies similar
– Fermentation characteristics
• PCR - limited success
• Electrophoretic karyotyping
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
20. Genome Structure - Lager Yeast
• Allopolyploid and probably aneuploid.
– Tetraploid
• Natural hybrid
– S. cerevisiae and S. bayanus
– S. cerevisiae and S. monacensis
• Contains two types of chromosomes
– S. cerevisiae type
– S. bayanus type
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
21. Genome Structure
• Gene order and function highly conserved
– Single chromosome transfer experiments
• Gene length similar, but nucleotide divergence.
– Low levels of recombination between homeologues
Gene Nt. Identity AA. Identity
ILV1 86 % 96 %
ILV2 85 92
MET2 84 94
URA3 79 93
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
22. Electrophoretic Karyotypes
Lager Ale WeissLab
XII
IV
XV, VII
I
VI
III
IX
V, VIII
XI
XVI, XIII
X
II, XIV
T C C
Lager Ale Labcerev.
bayan.
parad.
pastor.
XII
IV
XV, VII
I
VI
III
IX
VIII
XI
XVI, XIII
X
II, XIV
V
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
24. Ingredients
• Malted barley
• Cereal Adjunct
• Hops
• Water
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
25. Malted Barley
• Two types of barley
– 2-rowed
– 6-rowed
• Provides fermentable sugars,
flavor, and color.
• Malting process:
– Steeping
– Germination
– Kilning
• Purpose:
– Activate enzyme systems
– Preserve for brewhouse
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
26. Steeping
• Soak, aerate, drain.
• 2 days
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27. Germination
• Ventilated to remove CO2
• Repeated turning
• 4 to 5 days
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28. Cereal Adjuncts
• Types of adjuncts commonly used:
– Corn grits
– Rice
– Corn syrups (high maltose and dextrose)
• Purpose:
– Additional source of fermentable sugars
– Lighter body
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
29. Hops
• Spice of beer
– Provides aroma
and bitterness
• Flower (cone) of a
vine-growing plant
– Humulus lupulus
– Female triploid
• Used as:
– Whole cones
– Pellets
– Extracts
Lupulin Glands
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
31. The Brewing Process
Brewhouse
Fermentation
Lagering
Step Purpose
Starch Sugars
EthanolSugars
Carbonation
Flavor maturation
Wort production
Flavor production
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
32. The Brewing Process
Malt Mill
Mash Tun
Cereal
Cooker
Lauter Tun
Brew
Kettle
Hot Wort
Receiver
Wort
Cooler
FermentationBrink
Aeration
Lagering
Hops
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
33. Mash Tun / Cereal Cooker
• Activate malt enzymes
• Convert starch to
fermentable sugars
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
35. Brew Kettle
• Sterilization
• Protein coagulation
• Hop extraction
• Volatile removal
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
36. The Brewing Process
Malt Mill
Mash Tun
Cereal
Cooker
Lauter Tun
Brew
Kettle
Hot Wort
Receiver
Wort
Cooler
FermentationBrink
Aeration
Lagering
Hops
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
38. Wort Composition
Fermentable Sugars
** need to adjust to normal wort
52.9
28.4
16.1
2.6
0
20
40
60
80
100
Percent (% w/v)
Glucose FructoseMaltose Maltotriose
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
39. Wort Composition
Amino Acids (** adjust to normal wort)
107
132
65
53
30
49
63
151
89
31
126
269
56
93
105110
17
68
0
50
100
150
200
250
300
PPM
Ala
Arg
Asp
Glu
Gly
His
Ile
Leu
Lys
Met
Phe
Pro
Thr
Tyr
Val
Asn
Gln
Ser
Not included: Cys (2 ppm) and Trp (50 ppm)
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
40. The Brewing Process
Malt Mill
Mash Tun
Cereal
Cooker
Lauter Tun
Brew
Kettle
Hot Wort
Receiver
Wort
Cooler
FermentationBrink
Aeration
Lagering
Hops
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
41. Fermentation
• Yeast growth
• Alcohol and CO2
• Flavor compounds
• Large - 600,000 L
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
42. Lagering
• Carbonation • Off-flavor reduction
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
43. The Brewing Process
Malt Mill
Mash Tun
Cereal
Cooker
Lauter Tun
Brew
Kettle
Hot Wort
Receiver
Wort
Cooler
Fermentation
Brink
Aeration
Lagering
Hops
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
44. Balanced Growth
• Yeast growth affects beer flavor.
– Need balance between yeast growth and beer flavor.
• The brewer needs...
– Desired flavor profile in desired time.
– Sufficient yeast crop for subsequent fermentations.
• Oxygen is growth limiting nutrient.
– Control point
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
45. Yeast Metabolism During Fermentation
Sugars Oxygen
Amino Acids
Glucose
Pyruvate
TCA
Cycle
Energy
CO2
Ethanol
Acetaldehyde
Organic Acids
Amino Acids
Unsaturated Fatty Acids
Sterols
Esters
Higher
Alcohols
VDK
Sulfur
Volatiles
Membranes
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
46. Higher Alcohols
• Formed by the decarboxylation and reduction of
α-keto acids.
– From amino acid anabolism and catabolism.
Alcohol Amino Acid α-keto acid
Isoamyl Leucine α-keto-isocaproate
Amyl Isoleucine α-keto-3-methylvalerate
Isobutanol Valine α-keto-isovalerate
Propanol Threonine α-keto-butyrate
Alcoholic, solventy, and fruity flavor notes
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
47. Esters
• Closely linked to lipid metabolism - growth.
• Reaction of an alcohol and fatty acid intermediate
• Acetate esters
– Ethyl acetate solventy, fruity, sweet
– Isoamyl acetate banana
– Phenethyl acetate roses, honey, apple
• Fatty acid esters
– Ethyl caproate apple, aniseed
– Ethyl caprylate apple
– Isoamyl decanoate tropical fruits
Fruity flavor notes
Kindly provided by Tom Pugh and David Ryder of Miller Brewing Company
49. Thanks to David Ryder of Miller Brewing Company
and Tom Pugh, formerly of Miller Brewing Company,
for providing this presentation to the Saccharomyces Genome Database
for dissemination to the yeast community.
