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 + C 6 H 12 O 6 2 CH 3 CH 2 OH + 2 CO 2 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 20 Gravity - all malt 18 ºPlato wort 20C 1g/l rehydr. 15C 1g/l rehydr. 10C 1g/l rehydr. Yeast pitch rate 18 16 20C 0.5g/l rehydr. 15C 0.5g/l rehydr. 10C 0.5g/l rehydr. Yeast quality Temperature Gravity [ºPlato] 14 12 10 8 Pressure 6 4 Vessel geometry 2 0 0 24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 408 time [h]
Ethyl Acetate Esters 70 20C 1g/l rehydr. 15C 1g/l rehydr. 10C 1g/l rehydr. 60 20C 0.5g/l rehydr. 15C 0.5g/l rehydr. 10C 0.5g/l rehydr. [ppm] 50 40 30 20 Lower pitching rate resulted in higher ester production 10 0 6 regular wort 20C 1g/l rehydr. 20C 0.5g/l rehydr. Isoamyl Acetate 15C 1g/l rehydr. 15C 0.5g/l rehydr. 16 ºPlato wort 10C 1g/l rehydr. 10C 0.5g/l rehydr. adjunct wort Higher temperature led to higher ester production 4 [ppm] 2 Higher gravity resulted in higher ester concentrations 0 regular wort 16 ºPlato wort adjunct wort
60 20C 1g/l rehydr. Propanol 15C 1g/l rehydr. Higher Alcohols 10C 1g/l rehydr. 20C 0.5g/l rehydr. 15C 0.5g/l rehydr. 10C 0.5g/l rehydr. 50 40 [ppm] 30 20 10 0 300 250 200 regular wort 20C 1g/l rehydr. 20C 0.5g/l rehydr. Isoamyl Alcohol 15C 1g/l rehydr. 15C 0.5g/l rehydr. 16 ºPlato wort 10C 1g/l rehydr. 10C 0.5g/l rehydr. adjunct wort Higher gravity and higher temperature resulted in increased higher alcohol concentrations [ppm] 150 100 50 0 regular wort 16 ºPlato wort adjunct wort
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 Craft Brewing Reviving old beer styles and recipes Experimenting with new raw materials
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
Bavarian origin. Lager Yeast 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 Wheat American Pale Ale American Amber Ale American Brown Ale American IPA 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
5.5 8.0% abv Characteristics of NE IPA 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 Cream Ale American Wheat Blonde 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, mahoganycoloured 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
Yeast hybrids potential - Greater fermentation efficiency + Fermentation speed + Thermal tolerance + Ethanol tolerance - Greater diversity in sensory expression + Flavour + Aroma
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 Dryer Extruder RVF Emulsifier NaCl QC Extrusion -1 ºC 7 ºC Shipping Vacuum Packaging Sieving Drying Filtration (RVF) Commercial Yeast Tank
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 10 9 / 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 13 12 11 Effect of rehydration media & temperature on beer fermentation Rehydration for 60 minutes 30 ºC wort-water mix 15 ºC wort-water mix 20 ºC wort 30 ºC wort direct pitching in wort Extract [ºBrix] 10 9 8 7 6 0 1 2 3 4 5 6 7 Time (days)
Application Areas Smaller Breweries without propagation system Yeast shipment to license brewery Specialty Beer Production Bottle Conditioning Back up for yeast propagation
Simple Storage Advantages 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?