The Art of Brewing - PowerPoint Presentation

Slide1

The Art of Brewing

andThe Biology of Lager Yeast

Tom Pugh

Miller Brewing CompanySlide2

PurposeProvide a better understanding of...The brewing process

Types of brewing yeastsAttributes important to the brewerKindly provided by Tom Pugh and David Ryder of Miller Brewing CompanySlide3

The Art of Brewing

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Definition of BeerAn alcoholic beverage produced by the fermentation of sugar-rich extracts derived from cereal grains or other starchy materials.

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History of BrewingMan has been making beer since the dawn of civilization.Where grain was grown, beer was made.

Sumaria (4000 BC) SikaruEgypt (3000 BC) ZythumIndia (2000 BC) SuraChina (2000 BC) Kiu

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History of Brewing

Sumarian beer recipe3000 BCResembled liquid bread:Barley and EmmerSpices / fruitsNo HopsSafe, nutritious, and exhilarating beverage.

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The Role of Yeast in BrewingUnwittingly, 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.

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The Role of Yeast in Brewing1680 Antonie van Leeuwenhoek

Observed yeast in beer.1837 - Cagniard LatourMicrobe 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 . . .

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….small animal which sips sugar through its snout, and

excretes alcohol from its gut and carbonic acid from its

urinary organ.

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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

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Brewing Yeasts

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Types of Brewing YeastsTwo types of brewing yeasts, originally classified on flocculation behavior…

Top-fermentingAle yeastWeiss yeastBottom-fermentingLager yeast

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Weiss

Ale

Lab

Lager

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Ale YeastPredominant brewing yeast prior to the mid-1800s.

Displaced by lager yeastStrains are genetically more diverse - several originsWarm fermentation temperatures: 65 to 72 °F.

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Weiss YeastBavarian origins - closely related.

Produces beer that has spicy, clove, vanilla, and nutmeg flavor notes - POF.PAD1 gene phenylacrylic acid decarboxylaseDecarboxylation of ferulic acid forms 4-vinyl-guaiacol, which gives the characteristic clove flavor.Warm fermentation temperatures: 65 to 72 °F.

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Lager YeastBavarian origin.

1400s in Munich - cool fermentations (selective pressure)Taken to Pilsen and Copenhagen in 1840sPale malt, soft water, aromatic hopsBecame very popular - displaced ale yeastPopularity fueled by advances of Industrial RevolutionSteam power, refrigeration, railroads, pasteurization and filtration technologyStrains are closely related - common originsCool fermentation temperatures: 42 to 52 °FBeers are more delicate, clean, drinkable, and less aromatic.

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TaxonomyAle and Weiss yeasts - Saccharomyces cerevisiaePolyploid and probably aneuploid.

Non-matingSporulates poorly and poor spore viabilityLager yeast - Saccharomyces pastorianusS. cerevisiaeS. carlsbergensisS. uvarumSporulates very poorly - poor spore viability

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Distinguishing CharacteristicsColony morphology

Microscopic appearanceChain formationFermentation characteristicsFlocculation behavior / flavor compound profilesGrowth at 37 °CMelibiaseElectrophoretic karyotyping

Yeast 37 °C Melibiase POF

Lager - + -

Ale + - -

Weiss + - +

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Distinguishing CharacteristicsDifficult to distinguish between different lager yeasts using conventional techniques

Colony and cell morphologies similarFermentation characteristicsPCR - limited successElectrophoretic karyotyping

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Genome Structure - Lager YeastAllopolyploid and probably aneuploid.

TetraploidNatural hybridS. cerevisiae and S. bayanusS. cerevisiae and S. monacensisContains two types of chromosomesS. cerevisiae typeS. bayanus

type

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Genome StructureGene order and function highly conservedSingle 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

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Electrophoretic Karyotypes

Lager

Ale

Weiss

Lab

XII

IV

XV, VII

I

VI

III

IX

V, VIII

XI

XVI, XIII

X

II, XIV

T

C

C

Lager

Ale

Lab

cerev

.

bayan

.

parad

.

pastor.

XII

IV

XV, VII

I

VI

III

IX

VIII

XI

XVI, XIII

X

II, XIV

V

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The Brewing Process

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IngredientsMalted barley

Cereal AdjunctHopsWater

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Malted Barley

Two types of barley2-rowed6-rowedProvides fermentable sugars, flavor, and color.Malting process:Steeping

Germination

Kilning

Purpose:

Activate enzyme systems

Preserve for brewhouse

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Steeping

Soak, aerate, drain.2 days

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Germination

Ventilated to remove CO2Repeated turning4 to 5 days

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Cereal AdjunctsTypes of adjuncts commonly used:Corn gritsRice

Corn syrups (high maltose and dextrose)Purpose:Additional source of fermentable sugarsLighter body

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Hops

Spice of beerProvides aroma and bitternessFlower (cone) of a vine-growing plantHumulus lupulusFemale triploidUsed as:Whole conesPelletsExtracts

Lupulin Glands

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Hops

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The Brewing Process

Brewhouse

Fermentation

Lagering

Step

Purpose

Starch

Sugars

Ethanol

Sugars

Carbonation

Flavor maturation

Wort production

Flavor production

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The Brewing Process

Malt Mill

Mash Tun

Cereal

Cooker

Lauter Tun

Brew

Kettle

Hot Wort

Receiver

Wort

Cooler

Fermentation

Brink

Aeration

Lagering

Hops

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Mash Tun / Cereal Cooker

Activate malt enzymesConvert starch to fermentable sugars

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Lauter Tun

Strainer

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Brew KettleSterilization

Protein coagulationHop extractionVolatile removal

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The Brewing Process

Malt Mill

Mash Tun

Cereal

Cooker

Lauter Tun

Brew

Kettle

Hot Wort

Receiver

Wort

Cooler

Fermentation

Brink

Aeration

Lagering

Hops

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Wort CompositionCarbohydrates

Fermentable

Non-fermentable

73% Fermentable

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Wort CompositionFermentable Sugars** need to adjust to normal wort

Glucose

Fructose

Maltose

Maltotriose

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Wort CompositionAmino Acids (** adjust to normal wort)

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)

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The Brewing Process

Malt Mill

Mash Tun

Cereal

Cooker

Lauter Tun

Brew

Kettle

Hot Wort

Receiver

Wort

Cooler

Fermentation

Brink

Aeration

Lagering

Hops

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Fermentation

Yeast growth

Alcohol and CO

2

Flavor compounds

Large - 600,000 L

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Lagering

Carbonation

Off-flavor reduction

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The Brewing Process

Malt Mill

Mash Tun

Cereal

Cooker

Lauter Tun

Brew

Kettle

Hot Wort

Receiver

Wort

Cooler

Fermentation

Brink

Aeration

Lagering

Hops

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Balanced GrowthYeast 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

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Yeast Metabolism During Fermentation

Sugars

Oxygen

Amino Acids

Glucose

Pyruvate

TCA

Cycle

Energy

CO

2

Ethanol

Acetaldehyde

Organic Acids

Amino Acids

Unsaturated Fatty Acids

Sterols

Esters

Higher

Alcohols

VDK

Sulfur

Volatiles

Membranes

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Higher AlcoholsFormed by the decarboxylation and reduction of

a-keto acids.From amino acid anabolism and catabolism.Alcohol Amino Acid

a

-keto acid

Isoamyl Leucine

a

-keto-isocaproate

Amyl Isoleucine

a

-keto-3-methylvalerate

Isobutanol Valine

a

-keto-isovalerate

Propanol Threonine

a

-keto-butyrate

Alcoholic, solventy, and fruity flavor notes

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EstersClosely linked to lipid metabolism - growth.

Reaction of an alcohol and fatty acid intermediateAcetate estersEthyl acetate solventy, fruity, sweetIsoamyl acetate bananaPhenethyl acetate roses, honey, appleFatty acid estersEthyl caproate apple, aniseedEthyl caprylate appleIsoamyl decanoate tropical fruits

Fruity flavor notes

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Vicinal Diketones

Threonine

a

-ketobutyrate

pyruvate

a

-acetolactate

a

-acetohydroxybutyrate

Isoleucine

Valine

Diacetyl

Pentanedione

Buttery, butterscotch flavor

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Thanks to David Ryder of Miller Brewing Companyand Tom Pugh, formerly of Miller Brewing Company,for providing this presentation to the Saccharomyces Genome Database

for dissemination to the yeast community.