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San Diego California June, 2011. Choosing the Right Yeast. Chris White and Jamil Zainasheff. Yeast Chapters. Part One: The Importance of Yeast and Fermentation Part Two: Biology, Enzymes, and Esters Part Three: How to Choose the Right Yeast Selection Criteria - PowerPoint PPT Presentation


Choosing the Right Yeast

Choosing the Right YeastChris White and Jamil Zainasheff

San Diego CaliforniaJune, 2011


2Yeast ChaptersPart One: The Importance of Yeast and FermentationPart Two: Biology, Enzymes, and EstersPart Three: How to Choose the Right YeastSelection CriteriaBeer Styles and Yeast SelectionYeast StrainsMultiple StrainsBrettanomyces Part Four: FermentationPart Five: Yeast Growth, Handling, andPart Six: Your Own Yeast Lab Part Seven: Troubleshooting

3Yeast FermentationFigure 2.3


Species vs. StrainKingdomPhylumClass OrderFamilyGenusSpeciesStrain5

apiculatebottle (flask-shaped)

bipolarGraeme Walker, 20096Ale YeastWarm fermentation temperaturesFerments clean to fruityVariable flocculationUsually good top cropperProduces a great variety of beersStorage is good.

7Hefeweizen YeastFerments with wild character.Low flocculation Low diacetylCan produce sulfur. Ferments very rapidly, but not greater cell cropping is best way to collect slurry.Produce a small variety of beers.Ale Yeast, Specialty8Belgian Yeast Ferments with very unusual character-wild likeLow flocculationBottling with it?Low diacetylCan produce sulfur.Ferments very rapidlyCan be very fruityProduce a good variety of beers.Ale Yeast, Specialty9Lager Yeast TypesCold fermentation temperaturesFerments with clean characterNot drop out quickly.Will produce diacetyl.Will produce sulfur. Ferments slowly, and not grow very well.Usually not top crop.Produce a medium variety of beers.

10Brettanomyces is the main wild yeast used identified in strong English stock beer:

Claussen 1904 showed a brett inoculation of a 1.055 specific gravity beer would achieve the English character.

Shimwell 1947 confirmed the conditions: a 1.060 OG beer was essential to achieve a vinous wine like flavor, a beer under 1.050 would produce an unpalatable and turbid beer with insipid flavor and aroma. Shimwell said Brett can behave as a desirable organism in one beer and an undesirable one at one and the same brewery.

Usually used in secondary and bottle condition

Wild Yeast Types11Classification of Brett

Brettanomyces category grew as many new strains added. Many different synonyms. Dekkera and Brettanomyces: same thing, but Dekkera is the sexual form, it forms spores. Brettanomyces is non sporeforming, just as brewing yeast.

Multilateral budding

SO2 sensitive

Maltose and dextrin utilization variable

12Classification of Brett

5 species, based on ribosomal DNA sequence homology:

B. bruxellensisincludes B. intermediaB. lambicusB. custersiiB. anomalusincludesB. clausseniiB. custersianusB. naardenesisB. nanusnewest classification, added to the other 4 in 1990s

13Flavor Characteristics of Brett

Brettanomyces have the enzyme B-glucosidase.

B- glucosidase breaks down the wood sugar cellobiose,to produce glucose.

Cellobiose in barrels occurs as a result of the firing process used to toast the barrels.

B-glucosidase is inhibitied by ethanol, and pH optimum is 5-6, temperature optimum 40-50C.

New barrels contain higher amounts of cellobiose than used barrels, and therefore have the potential to support higher Brettanomyces populations.Wineries are encouraged to destroy barrels if Brett develops.Fruity-like flavors from glucosidase activity?

14Flavor Characteristics of Brett

Isovaleric acid, guaiacol, plastic like compounds; 4-ethyl guaiacol (4EG) and 4-ethyl phenol (4EP)produced by the decarboxylation of the hydroxycinnamic acids p-coumaric and ferulic acid 4EP used to confirm Brett presence.

15Bacteria Types

Usually beer spoilage organisms10% of the size of yeastMuch simpler organism16

LactobacillusPediococcusAcetic Acid Bacteria17Bacterial differencesAerobic vs. anaerobicGram positive vs. Gram negative- Gram staining- req. special stains and microscope with oil immersion capability- Easy test3% KOH solution - Increased viscosityGram negative- No viscosity Gram positive18

Bacterial I.D.


Bacterial Flavors/ContributionPediococcus damnosus

acidity, sourness and diacetylLactobacillus delbrueckii acidity, sourness20Why Choose the Right Yeast?

Does it matter?Creativity, the desire to produce the best beer possible

21Easily ProvenFerment the same wort with multiple yeast strains

Different resulting beers even with high gravity, high hops, etc.

22Yeast BehaviorDifferent strains can show differences in:Oxygen requirementsFermentation time lineCell counts in tankAromaViabilityNutrient requirementsDiacetyl restYeast collectionYeast storageTo name a few

Does not need to be completely mapped out in beginning.

23Strain Selection ProcessJamil methodSimple, straightforwardThere is no magicSet goals for the beerParameters (ABV, IBU, SRM)Flavor concept (malty, hoppy, other?)Determine at least one or two key requirementsSelect likely yeast candidatesYou can try them allOr use goals and key requirements to narrow choicesTest batchesKeep tests consistent, adjust later

24Determining Key RequirementsFlavor, often the most importantBitterness, hop characterMalt sweetness, malt characterAlcohols, esters, and othersAlcohol toleranceExtreme beer?Most yeasts handle considerable ABVAttenuationABV target, residual sweetnessFermentation temperatureSome Belgian strains require temp pushOther considerationsSpeed of fermentation, storage, flocculation25Example: Smoked BelgianGoal in mind7-8% ABVSlight but evident smoke characterDark, rich malty characterSome malty sweetnessBalancing bitterness, no hop characterRecipePils, Munich, Rauch, Special B, Carafa Special, SugarHallertau17 P, 23 IBU, 19 SRM26Example: Key Flavor ConsiderationsSmoke phenol from gristPlus fermentation, could be overwhelmingLow phenol, complimentary phenol yeastNeed some additional complexityFruity esters, Belgian characterMalt characterEnhanced malt character, with subtle smoke characterSome yeasts enhance, others subdueMalt sweetnessAvoiding too heavy and sweet or too dryAttenuation 75 86% to result in 7 8% ABV27Example: Test BatchesPitch rate 0.75 M/P/ml, 68 F to 74 F, 8-10 ppm O2

Antwerp (WLP515)75% Apparent, 4.3 P, 7.0 %ABVMalty, rich, full, more rauch characterAbbey (WLP530)77% Apparent, 3.8 P, 7.3 %ABVSlightly full, drier than 515, fruityBelgian Strong (WLP545)92% Apparent, 1.3 P, 8.6 %ABVDry, spicy, alcohol evident, lowest malt character

28Example: AdjustmentsAntwerp (WLP515)Increase attenuation without losing malt characterSecond yeast? Mash adjustment? Grist?Abbey (WLP530)Reduce fruity character, let rauch be more evidentPitching rate? O2? Nutrient? Temp? More rauch?Belgian Strong (WLP545)Refine alcohol character, less dryO2? Pitch rate? Temp? Mash?Blending?Worthwhile?29Thank you!Questions?



Diversity of yeast cell morphology

Sheet1MicroorganismGrowthGramKOH resultCell morphologyCatalaseAcetobacterStrictly aerobicNegativeviscousshort rodspositiveGluconobacterStrictly aerobicNegativeviscousshort rodspositiveObesumbacteriumfacul. AnaerobicNegativeviscousRodspositiveRahnellafacul. AnaerobicNegativeviscousRodspositiveLactobacillusAnaerobicPositive/variablenon-viscousRodsnegativePediococcusAnaerobicPositivenon-viscousCoccinegative