Yeast Flavour & The Evolution of Beer Styles

Robert Percival Lallemand Brewing

Content

• Contribution of yeast to beer flavour • Development of beer styles

• The role of yeasts in beer styles

• Commercial availability and application of dried

brewing yeasts

Contribution to Beer Flavour Yeast?

Importance Of Yeast In Brewing

“Yeast can be the single most important ingredient the brewer selects. The joke around the brew house is that in reality we work for the yeast.” - Garrett Oliver

Primary Chemical Change During Fermentation

C6H12O6 2 CH3CH2OH + 2 CO2

+

Glucose Ethanol + Carbon Dioxide

Important Reaction Products From Yeast Metabolism

• Higher alcohols

• Organic acids

• Aldehydes and ketones

• Esters

• Lipids

• Sulphur compounds

• Phenols

Variables Affecting Fermentation • Wort composition & pH

• Wort dissolved oxygen (DO)

• Yeast strain

• Yeast pitch rate

• Yeast quality

• Temperature

• Pressure

• Vessel geometry

Gravity - all malt 18 ºPlato wort

0 24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 4080

2

4

6

8

10

12

14

16

18

2020C 1g/l rehydr.

20C 0.5g/l rehydr.

15C 1g/l rehydr.

15C 0.5g/l rehydr.

10C 1g/l rehydr.

10C 0.5g/l rehydr.

time [h]

Gra

vity

[ºP

lato

]

Esters

Isoamyl Acetate

regular

wort

16 ºP

lato w

ort

adjunct

wort0

2

4

6

20C 1g/l rehydr.

20C 0.5g/l rehydr.

15C 1g/l rehydr.

15C 0.5g/l rehydr.

10C 1g/l rehydr.

10C 0.5g/l rehydr.

[ppm

]

• Lower pitching rate resulted in higher ester production

• Higher temperature led to higher ester production

• Higher gravity resulted in higher ester concentrations

Ethyl Acetate

regular

wort

16 ºP

lato w

ort

adjunct

wort0

10

20

30

40

50

60

70 20C 1g/l rehydr.

20C 0.5g/l rehydr.

15C 1g/l rehydr.

15C 0.5g/l rehydr.

10C 1g/l rehydr.

10C 0.5g/l rehydr.

[ppm

]

Higher Alcohols

• Higher gravity and higher temperature resulted in increased higher alcohol concentrations

Propanol

regular

wort

16 ºP

lato w

ort

adjunct

wort0

10

20

30

40

50

60 20C 1g/l rehydr.

20C 0.5g/l rehydr.

15C 1g/l rehydr.

15C 0.5g/l rehydr.

10C 1g/l rehydr.

10C 0.5g/l rehydr.

[ppm

]

Isoamyl Alcohol

regular

wort

16 ºP

lato w

ort

adjunct

wort0

50

100

150

200

250

300

20C 1g/l rehydr.

20C 0.5g/l rehydr.

15C 1g/l rehydr.

15C 0.5g/l rehydr.

10C 1g/l rehydr.

10C 0.5g/l rehydr.

[ppm

]

Manipulation Of Variables • From just one yeast strain a brewer can

manipulate fermentation conditions to produce a vast spectrum of flavours!

Brewer’s ADY

Craft Brewing

• Brewing market consolidated => beers were “homogenous”

• In the 80’s a counter movement started in the US

• Reviving old beer styles and recipes

• Experimenting with new raw materials

Craft Brewing

How Did Styles Develop?

• Local barley types • Different ways of making

malt • Local water source • Different yeast strains,

shared yeast strains • Different temperature ranges

– ability to store cold • Different cross-cultural

influences • Introduction of hops

Development of beer styles

Availability of materials

Grist, Hops (and flavourings), Liquor

Fermentation by local Microbiological Flora

Refinement of beer styles

Purification and selection of strain(s)

Standardisation of raw materials and brewing conditions

Established beer style

Lager Yeast • Bavarian origin.

– 1400s in Munich - cool fermentations (selective pressure) – Taken to Pilsen and Copenhagen in 1840s

• Became very popular - displaced ale yeast

• Popularity fueled by advances of Industrial Revolution

– Steam power, refrigeration, railroads, pasteurization and filtration technology

• Cool fermentation temperatures: 5 to 12 ºC

• Natural Hybrid

Characteristics of Lager Beer

• Strains are closely related - common origins

• Beers are more delicate, clean, drinkable, and less aromatic.

• Low bitterness, simple grist composition.

Lager Yeast

Lager Pilsner Helles Vienna Bock

Schwartzbier Märzen

Characteristics of West Coast Ale Yeast

• Aroma: Neutral with a slight ester

• High attenuation

• Fermentation range: 15 – 22C

• Flocculation: Medium to High

• Popular modern style

Characteristics of West Coast Ale

• 4.5 - 5.5% abv

• Straw like golden to deep amber colour

• Complex malty, bready/biscuity

• Moderate/strong USA hops, citrus & pine

• Medium bodied, moderate/high carbonation

American West Coast Ale

American Barleywine

American Pale Ale

American Amber Ale

American Brown Ale American IPA

American Wheat Blonde Ale Cream Ale Kölsch Imperial IPA

Irish Red Ale ESB Scottish Ale Strong Scottish Ale Strong Ale

Characteristics of New England Yeast

• Aroma: High esters – tropical and stone fruit

• Med - High attenuation

• Fermentation range: 18 – 22C

• Flocculation: Medium to High

• Increasingly popular modern style

Characteristics of NE IPA • 5.5 – 8.0% abv

• Straw like golden to deep amber colour

• Light to strong haze

• Low bitterness (IBU), high late

hop/aroma

• Strong USA hops, citrus & pine

• Full bodied, smooth malty/bready/oaty

• moderate/high carbonation

• Tropical and aromatic yeast notes

LalBrew New England

NE IPA IPA ESB American Wheat Blonde Ale

Cream Ale

• Fermentation: Longer lag phase. 5-7 day primary fermentation

• Attenuation: High attenuation (75-80%)

• 100g/hL pitching requirement

• Flavour: High ester. Distinct stone fruit and peach, complex fruit.

Characteristics of British Ale Yeast

• Aroma: Fruity/ester

• Attenuation: Medium

• Fermentation temp: 18-22C • Flocculation: Medium - High

Characteristics of British Ale (ESB)

• Strong (5-6% abv),

• Full-bodied, mahogany-coloured

• Mellow bitterness • Complex malty notes- biscuit

flavours and soft malt toffee, brewed with Pale Ale and Crystal malts

British Ale

ESB Cream Ale Blonde Ale Bitter Special/Best Bitter

Scottish Ale Irish Red Ale Brown Ale Porter Sweet Stout

English IPA Old Ale Mild

• Fermentation: Vigorous fermentation complete within 3-5 days.

• Attenuation: Medium attenuation preserves some beer complexity

• Flavour: Well balanced aromatic profile, moderate ester.

Beer styles based around yeast: Weissbier/Hefeweizen

• Origins in C16th Bavaria.

• Favoured by royals, later gaining widespread popularity.

• Nearly dies out by C19th but revived by G.Schneider.

• Top fermenting ale yeast, fermented at warm temps.

Characteristcs of Bavarian Wheat Beers

• Unique yeast with complex flavour profile.

• Prominent esters – Banana, vanillia, bubblegum, apple.

• Phenols often present – 4VG (clove, ferulic acid), spices.

• Low hopping, simple grist composition.

Wheat Beer Yeast

Weizen Hefeweizen Dunkelweizen Weizenbock American

Style Hefeweizen

Beer styles based around yeast: Saison

• French/Belgian origins (Wallonia).

• Farm house ales traditionally brewed in winter, stored until summer.

• Seasonal farm workers ‘Saisonniers”.

• Top fermenting, warm temps.

Characteristics of Saison Beers

• S.Cervisiae var diastaticus

• Robust yeast with complex ester flavour profile (lemon/orange).

• Prominent ‘earthy’ yeast notes and spices (pepper).

• Very dry finish; high attenuation.

• Low hopping, simple grist composition.

Belgian Saison Style Beer yeast

Saison Bière de Garde

Belgian style beers

Wild Yeast: Brettanomyces

• Can utilise broad range of sugars (inc. dextrins)

• Diverse sub species

• Does not contribute a lot of acidity on its own

• Slow acting

• Secondary Fermentation

Characteristics of ‘Wild’ Beers

• Robust yeasts with complex flavour profile (species dependent)

• Prominent ‘funky’ yeast notes and spices (phenolics).

• Typically dry finish; high attenuation.

• Low hopping, often used in sour beer styles.

Brettanomyces

Saison Bière de Garde

American Wild

Sour Beer Styles

Imperial Stout

Trappist beer

Yeast hybrids – potential

• Development of Interspecific hybrids:

S. cerevisiae

X S.euybayanus, S.mitakae, S.kudriavzevii

= Novel strain characteristics

- Greater fermentation efficiency + Fermentation speed + Thermal tolerance + Ethanol tolerance

- Greater diversity in sensory expression + Flavour + Aroma

Yeast hybrids – potential

Yeast hybrids – potential

Origin Efficiency Aroma POF Temp

S. cerevisiae X S. eubayanus -- Clean, slightly fruity aroma - Low/High

S. cerevisiae X S. eubayanus -- Clean, fruity aroma + (slight) Low/High

S. cerevisiae X S. eubayanus ++ Neutral to slightly fruity aroma + (slight) Low/High

S. cerevisiae X S. mikatae ++ Extremely fruity + (slight) Low/High

Are there New Styles to be developed?

• Yes! Beer styles are changing as we speak

• Brewers (and Marketers) like to try new things

• Driven by home-brewers, beer enthusiasts and pro brewers

• Brewers want to sell more beer, want to keep consumers interested in their brands

• Consumers want an experience in drinking, not just beer as a thirst quencher

• Brewers must still bear in mind “drinkability”

Commercial Availability of Yeast

• Anyone can brew any style!

Dry Beer Yeast - Production

-1 ºC – 7 ºC

Commercial Yeast Tank

Filtration (RVF)

Extrusion

Drying Sieving Vacuum Packaging

Shipping

Emulsifier

QC

NaCl

Dryer

Extruder RVF

Quality Control

• Viability (Methylene blue, YPD)

• Vitality (Clinitest)

• Wild Yeast (Lysine, LWYM, LCSM)

• Bacteria (PCA, MRS, UBA, SDA)

• Petite mutants (TTC)

• Beer fermentation

• DNA fingerprinting

Typical Analysis

• Dry weight: 93-95%

• Viability: 5 x 109 / gram

• Wild yeast: <1 per 1 million yeast cells

• Bacteria: <1 per 1 million yeast cells

• Recommended pitching rate: 50 – 100g/hl

Handling: Rehydration

• Rehydration temperature

• Rehydration media

Rehydration Media

• No deionised/distilled water (osmotic pressure)

• No undiluted wort Cell membrane is more permeable during the first few minutes and toxic material can pass into the cell

• Best sterilized / boiled tap water or diluted wort (lager yeast)

Rehydration Step 1 (Ale Yeast)

• Sprinkle the yeast on the surface of ten (10) times its weight clean, sterilized (boiled) tap water at 30 – 35 C

• DO NOT STIR !!! • Leave for 15 Min.

undisturbed at 30 – 35 C

• Foam or no foam is no indication of vitality

Rehydration Step 2 (Ale Yeast)

• After 15 Min. stir gently until all yeast is suspended

• Leave undisturbed for another 5 Min.

• Attemperate in steps (5 min) of 10 Celsius degree to the temperature of the wort by mixing aliquots of wort

Rehydration Lager Yeast

Effect of rehydration media & temperature on beer fermentation Rehydration for 60 minutes

6

7

8

9

10

11

12

13

0 1 2 3 4 5 6 7Time (days)

Extr

act [

ºBrix

]

30 ºC wort-water mix 15 ºC wort-water mix

20 ºC wort 30 ºC wort

direct pitching in wort

Application Areas

• Smaller Breweries without propagation system

• Yeast shipment to license brewery

• Specialty Beer Production

• Bottle Conditioning

• Back up for yeast propagation

Advantages

• Simple Storage

• Long shelf life compared to fresh yeast

• Simple Transport

• Easy Handling

• No Propagation necessary/ready in pitchable size

• Guaranteed Quality

• No aeration of wort necessary

Conclusions • Yeast contribution to beer flavour is significant.

• From just one strain a brewer can manipulate a wide range in flavour and characteristics.

• History and evolution of yeasts is significant in process of isolating and purifying strains.

• Yeasts are at the heart of many of the most popular beers styles.

• Modern beer market – Demand for commercially availability of yeasts.

• There are no rules!

Questions?