Introduction to Introduction to Alcoholic Alcoholic

BeveragesBeveragesRobert S. WallaceRobert S. Wallace

Department of Ecology, Evolution, and Organismal Department of Ecology, Evolution, and Organismal BiologyBiology

Iowa State UniversityIowa State UniversityAmes, Iowa 50011Ames, Iowa 50011

Introduction to Introduction to Alcoholic Beverages:Alcoholic Beverages:

BeerBeer

What is Beer?What is Beer?

• A fermented (alcoholic) beverage derived A fermented (alcoholic) beverage derived from grains. from grains.

• Flavorings are often added to balance Flavorings are often added to balance residual sweetness of unfermented sugars residual sweetness of unfermented sugars and other polysaccharides; bitter flavors and other polysaccharides; bitter flavors used most.used most.

• The fermentation organism is typically a The fermentation organism is typically a yeast species within the genus yeast species within the genus SaccharomycesSaccharomyces. .

• Most beers have natural or intentionally Most beers have natural or intentionally added carbonation.added carbonation.

Origins of BeerOrigins of Beer

• Earliest evidence for the deliberate production of Earliest evidence for the deliberate production of beer dates to at least 5,500 BCE in Sumeria.beer dates to at least 5,500 BCE in Sumeria.

• Use of domesticated barley is evident from Use of domesticated barley is evident from impressions of grains in vesselsimpressions of grains in vessels

• Original beers were likely spontaneously Original beers were likely spontaneously fermented, and may have been derived by fermented, and may have been derived by soaking roasted barley cakes in water.soaking roasted barley cakes in water.

• Beers that had finished fermenting likely had Beers that had finished fermenting likely had sediment and floating debris; the clear liquid in sediment and floating debris; the clear liquid in the middle was drunk through reeds – precursors the middle was drunk through reeds – precursors of our modern ‘straws’.of our modern ‘straws’.

A Sumerian bas-relief sculpture depicting the drinking beer from amphora-like vessels.

• Selection for attributes of “full” heads that do not shatter, and multiple fruits drove the domestication process

• Different qualities selected for various uses of the grain: e.g. baking versus brewing.

6-row6-row 2-row2-row

•Palea and lemma remain in cleaned grains.

•These form the ‘husk’ that is desirable in barley to form the filter bed during mashing and sparging.

                                                                         

        

MaltingMalting• Malting is the process of germinating viable seed to allow the Malting is the process of germinating viable seed to allow the

embryo to develop enzymes (amylases, and others) which are embryo to develop enzymes (amylases, and others) which are capable of breaking-down stored carbohydrates, typically in capable of breaking-down stored carbohydrates, typically in the form of starch, and then stopping this growth at a specific the form of starch, and then stopping this growth at a specific stage of development through kilning. stage of development through kilning.

• The process begins by The process begins by imbibing the seed with waterimbibing the seed with water to initiate to initiate germination. germination.

• Germination under aerobic conditions continues until a Germination under aerobic conditions continues until a critical stage of development, when the process is rapidly critical stage of development, when the process is rapidly stopped by heating and drying the germinated seed.stopped by heating and drying the germinated seed.

• Traditional malting techniques included carrying out this Traditional malting techniques included carrying out this process on the floors of special facilities, and processing the process on the floors of special facilities, and processing the germinating grains by hand.germinating grains by hand.

• Modern techniques involve bulk processing of grains in Modern techniques involve bulk processing of grains in specialized malthouses, most involving the use of automated specialized malthouses, most involving the use of automated troughs or (Saladin) boxes in environmentally controlled troughs or (Saladin) boxes in environmentally controlled conditions. conditions.

Floor Malting - DeWolf-Cosyns Malting, Brussels, Belgium

Adolph Coors Brewing Company, Golden, Colorado

Cargill Malting, Stevens Junction, Wisconsin

• Following imbibition of the grain in the steeping tanks, the grain is sent through pipes in a grain-water slurry.

• The grains fill a long trough which is kept under cool temperatures and high humidity which favors germination condition.

• A series of automated augers turn the grainbed during the germination process to assure uniformity and maintain aerobic conditions for the sprouting grains.

Malting: Filling the Saladin Box

Saladin Box - Cargill Malting, Stevens Junction, Wisconsin

Adolph Coors Brewing Company, Golden, Colorado

Kilning of Malt - IKilning of Malt - I

• Once the critical stage of germination and embryo growth Once the critical stage of germination and embryo growth has been achieved, the process needs to be abruptly has been achieved, the process needs to be abruptly stopped. stopped.

• The germinated grain is transferred to a kilning box where The germinated grain is transferred to a kilning box where hot, dry air is passed through the grain bed, which kills the hot, dry air is passed through the grain bed, which kills the embryo (without effecting the enzyme characteristics), and embryo (without effecting the enzyme characteristics), and dries the malt to an acceptable moisture content. dries the malt to an acceptable moisture content.

• The malt is then cleaned of rootlets and other structures, and The malt is then cleaned of rootlets and other structures, and prepared for packaging and shipment.prepared for packaging and shipment.

• Extensive biochemical and physical assays determine the Extensive biochemical and physical assays determine the malts brewing (or other) characteristics.malts brewing (or other) characteristics.

• Specialized kilning of certain malt products under a range of Specialized kilning of certain malt products under a range of temperature and moisture conditions, for varying lengths of temperature and moisture conditions, for varying lengths of time, produce ‘specialty’ malts that are widely used in time, produce ‘specialty’ malts that are widely used in brewing.brewing.

Cargill Malting, Stevens Junction, Wisconsin

Kilning of Malt - IIKilning of Malt - II

• Kilning done with wet malt under closed conditions Kilning done with wet malt under closed conditions results in “crystal” or “caramel” malt due to results in “crystal” or “caramel” malt due to thermal saccharification of starches. thermal saccharification of starches.

• ““Roasting” or dry kilning of malt results in Roasting” or dry kilning of malt results in ‘darkening’ or ‘browning’ of the grains due to ‘darkening’ or ‘browning’ of the grains due to Maillard reactions:Maillard reactions:

α-α-amino acids +amino acids +sugarssugars

melanoidinsmelanoidins

(Maillard products)(Maillard products)[O[O22]]

heatheat(colorless or pale)(colorless or pale)

(dark color)(dark color)

Malt color is determined by kilning – Measured in degrees Lovibond

Melanoidins contribute to beer color…..

Other Grains Used in Other Grains Used in BrewingBrewing

• A variety of grains other than barley are used in the A variety of grains other than barley are used in the brewing process as brewing process as adjunct grains. adjunct grains. These typically do These typically do not have the same enzymatic composition as barley, but not have the same enzymatic composition as barley, but do provide alternative sources of fermentable do provide alternative sources of fermentable carbohydrates, along with a range of aromatic and other carbohydrates, along with a range of aromatic and other flavor compounds.flavor compounds.

• Main Adjunct Grains:Main Adjunct Grains:Wheat – Wheat – Triticum aestivumTriticum aestivumRice – Rice – Oryza sativaOryza sativaOats – Oats – Avena sativaAvena sativaRye – Rye – Secale ceraleSecale ceraleCorn – Corn – Zea maysZea maysSorghum – Sorghum – Sorghum bicolorSorghum bicolorMillet – Millet – Panicum milleaceumPanicum milleaceum

Starch Conversion - MashingStarch Conversion - Mashing

• Necessary to activate enzymes produced by Necessary to activate enzymes produced by grass embryos by re-hydrating crushed grains. grass embryos by re-hydrating crushed grains.

• Temperature raised to optimum temperature to Temperature raised to optimum temperature to enable enzymatic breakdown of starch into enable enzymatic breakdown of starch into component sugars. component sugars.

• Selection of temperature and duration of mash Selection of temperature and duration of mash will determine fermentability of the resulting will determine fermentability of the resulting wortwort..

• Mashing also liberates medium molecular weight Mashing also liberates medium molecular weight proteins which contribute to mouthfeel and proteins which contribute to mouthfeel and heading characteristics.heading characteristics.

Teak Mash Tuns – Shepherd-Neame Brewery, Faversham, Kent, England

Teak Mash Tun – Shepherd-Neame Brewery, Faversham, Kent, England

Mash Tun No. 1 – Fuller, Smith & Turner Brewery, Chiswick, London, England

Carbohydrate Components of MaltCarbohydrate Components of Malt

• Poly 1,4 glucose, amylose (starch)Poly 1,4 glucose, amylose (starch)- straight chains- straight chains- simple, easily-digested by amylases- simple, easily-digested by amylases

• Beta-glucansBeta-glucans- have both 1,4 and 1,3 bonds- have both 1,4 and 1,3 bonds- partially digestible with amylases- partially digestible with amylases

• AmylopectinsAmylopectins - branched starch molecules- branched starch molecules - branching with 1,6 bonds typical- branching with 1,6 bonds typical - partially fermentable- partially fermentable

Mashing – Amylase ActivityMashing – Amylase Activity

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……G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G G-GG-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G-G G-G

……G-G-G-G-G-G-G-G-G-G-G-G-G-G-G G-G G-G G-G G-G G-GG-G-G-G-G-G-G-G-G-G-G-G-G-G-G G-G G-G G-G G-G G-G

Alpha Amylase Alpha Amylase (t(too = 158 = 158º º F; 70F; 70ºº C) C)

Beta Amylase Beta Amylase (t(too = 140 = 140º º F; 60F; 60ºº C) C)

Sweet Wort and BoilingSweet Wort and Boiling

• Following mashing of the grain, the solubilized Following mashing of the grain, the solubilized sugars and oligosaccharides in solution are run sugars and oligosaccharides in solution are run off the grain bed to a boiling vessel (the “kettle”). off the grain bed to a boiling vessel (the “kettle”).

• The “spent” grain bed is washed with hot (170The “spent” grain bed is washed with hot (170ºº F F 7777º º C) water in a process known as C) water in a process known as spargingsparging to to dissolve residual sugars. dissolve residual sugars.

• At this point, the sugar solution is termed At this point, the sugar solution is termed ‘sweet ‘sweet wort’wort’ which is then which is then boiledboiled for an hour or more. for an hour or more.

• During the boiling process, During the boiling process, hopshops are added and a are added and a variety of chemical processes occur which result variety of chemical processes occur which result in the liquid becoming bitter; thus it is now in the liquid becoming bitter; thus it is now termed termed ‘bitter wort’‘bitter wort’..

Hops – Hops – Humulus lupulusHumulus lupulus(Family Cannabaceae)(Family Cannabaceae)

• Hops are Hops are dioeciousdioecious vining perennials, having extensive stem vining perennials, having extensive stem structures:structures:– Aboveground Aboveground stems (bines)stems (bines) and leaves dying at the end of the and leaves dying at the end of the

growing season in most areas.growing season in most areas.

– Belowground Belowground stems (rhizomes)stems (rhizomes) and and rootsroots overwintering. overwintering.Rhizomes serve as primary means for vegetative (clonal) Rhizomes serve as primary means for vegetative (clonal) propagation of female plants for commercial production. propagation of female plants for commercial production.

• Desired product is the dried inflorescences (“strobiles” or Desired product is the dried inflorescences (“strobiles” or “cones”) of the female plant which have “cones”) of the female plant which have lupulin glandslupulin glands on the on the bracts and bracteoles which subtend the minute flowers. bracts and bracteoles which subtend the minute flowers.

• Male hop plants are used primarily for breeding purposes’ in Male hop plants are used primarily for breeding purposes’ in some cases male hops are planted to assist in improving some cases male hops are planted to assist in improving yield (e.g. British varieties).yield (e.g. British varieties).

• Female Female inflorescences (“burs”)inflorescences (“burs”) continue development even if continue development even if flowers are not pollinated (wind).flowers are not pollinated (wind).

Cannabaceae:

The Hemp/Hop

Family• Related to the Elm (Ulmaceae), Mulberry (Moraceae) and Stinging Nettle (Urticaceae) families.

• Wind-pollinated.

• Family with 2 genera:

Cannabis – 1 (2) species.

C. sativa [hemp; marijuana]

Humulus – 2 (3) species

H. japonicus – Japanese hop

H. lupulus – brewing hop

Cannabis sativa L. Hemp cultivar (male)

Humulus lupulus Brewing hop – (female)

Yakima Valley, Washington

Yakima Valley, Washington

• Desired product is the dried dried inflorescences (“strobiles” or “cones”) of the female plant which have lupulin glands on the bracts and bracteoles which subtend the minute flowers.

• Male hop plants are used primarily for breeding purposes’ in some cases male hops are planted to assist in improving yield (e.g. British varieties).

• Female inflorescences (“burs”) continue development even if flowers are not pollinated (wind).

Female inflorescences

of Hops (“Cones”)

Female hop Inflorescences: “Bur stage”• Female inflorescences have all pistillate flowers with stigmas extending beyond bracts and bracteoles. This is considered the “bur stage”

• Stigmas are receptive to windborne pollen at this stage.

•Female inflorescences (“burs”) continue development even if flowers are not pollinated (wind).

Mature FemaleHop inflorescence

• Composed of bracts and bracteoles that completely cover the minute pistillate flowers.

• Compound inflorescences (groups of individual cones) arise from axillary branches.

• Hops are ready to harvest when the bracts and bracteoles become papery and somewhat dry. Lupulin production will have achieved its maximum at this stage.

BractBract

Rachis (“strig”)Rachis (“strig”)

BracteoleBracteole

Hop Flowers

• Female flowers are found in the axils of each bract.

• The ovaries are covered with lupulin glands.

•If flowers are pollinated, the fruit that develops will be thin-walled and will surround a single seed.

•Unpollinated flowers will not develop fully, and the entire inflorescence may lack any fertile seed.

Hop Picking: Traditional Methods

• All picking was done by hand.

• Extremely labor intensive.

• Often carried out by migrant or other seasonal workers.

• Paid for amount harvested.

Hop Harvest: High Trellis System

Harvested Not Harvested

Grandview, Washington

• Mature hop inflorescences (“cones”) are plucked from hop bines using wire “fingers” which are run against suspended bines.

• Cones are moved on to further cleaning operations.

•Leaf and stem material is then chopped-up, and sent to waste piles; this material is then spread on fields as ‘green manure”.

Mechanical Hop Picking

Traditional Methods: Traditional Methods: ‘‘Oast House’ – England – Typically coal fired.Oast House’ – England – Typically coal fired.Hop Kiln – United States – Typically wood fired.Hop Kiln – United States – Typically wood fired.

Both relied on convection and slatted floors.Both relied on convection and slatted floors.Fire risk was always high in these systems.Fire risk was always high in these systems.Hops baled using ‘pocket’ technique, or screw type press.Hops baled using ‘pocket’ technique, or screw type press.

Modern methods:Modern methods:Forced hot air, perforated floor system, over moveable cloth mesh.Forced hot air, perforated floor system, over moveable cloth mesh.Careful monitoring of temperature and blower volume possible.Careful monitoring of temperature and blower volume possible.Dried at ca. 150Dried at ca. 150°-155° F for 8 to 12+ hours with forced hot air.°-155° F for 8 to 12+ hours with forced hot air.Cooled without adding heat for ca. 1 hour at ambient temperature.Cooled without adding heat for ca. 1 hour at ambient temperature.

• Hops are considered ‘dry’ when the strig (rachis) becomes less pliable, Hops are considered ‘dry’ when the strig (rachis) becomes less pliable, and nearly snaps when bent, usually around 9% MC.and nearly snaps when bent, usually around 9% MC.

Experienced ‘hop dryer’ responsible for monitoring progress of drying Experienced ‘hop dryer’ responsible for monitoring progress of drying operation. operation.

KilningKilning

Hop Kiln:Slotted metal floor and net-like cloth covering.

• Allows for high volume of hot air to be blown underneath kiln to pass through the bed of drying hops.

• Cloth used to moved dried hops off of kiln and onto ‘baling floor’ following a period of cooling and conditioning.

• Forced hot air (approx. 150O to 155OF is pushed through bed of wet hops for 8 to 12 hours.

• Water removed rapidly; hop cones become “papery” and somewhat brittle.

• Upon cooling hops recover some moisture, and are allowed to cool for a period of time.

• The hops are then “dropped” off of the kiln, and prepared for baling.

Kilning Hops: Rapid and careful drying

Kilned hops allowed to cool; in some cases hops take up atmosphericKilned hops allowed to cool; in some cases hops take up atmospheric moisture during cooling which makes them less brittle.moisture during cooling which makes them less brittle.

Hops from various parts of the kiln bed are mixed to assure uniform Hops from various parts of the kiln bed are mixed to assure uniform

overall moisture content. overall moisture content.

Dried, cooled hops are then transferred to baling areaDried, cooled hops are then transferred to baling area..

Automated machines weigh 200 pound portions of dried hops whichAutomated machines weigh 200 pound portions of dried hops which pass into a hydraulic press apparatus; bales are then compressedpass into a hydraulic press apparatus; bales are then compressed between pieces of burlapbetween pieces of burlap. .

Burlap pieces are sewn shut, and the bale labeled, weighed, checked Burlap pieces are sewn shut, and the bale labeled, weighed, checked for moisture content and prepared for transport and cold storage for moisture content and prepared for transport and cold storage. .

Baling Baling

• Compressed hops are then sewn into a bag made from burlap, a natural plant fiber made from jute (Corchorus capsularis; Tiliaceae).

• Once sewn shut, the weight is checked and the bales are set out to check moisture content.

• Physical quality of the hops is then assessed using a ‘hop tryer’ and a moisture meter.

• Once checked, the hop bales are then moved to cold storage.

Completion of Hops Baling: Burlap Cloth

Hopunion, Yakima, Washington

Kettle Reactions - BoilingBoiling accomplishes several positive processes for the wort prior to fermentation:

• Sterilizes wort so that only desired fermentation organism accomplishes the conversion of wort to beer.

• Coagulates protein which is removed from later stages; also may complex and remove solubilized tannins.

• Volatilizes undesirable compounds, e.g. dimethylsulfides (DMS) which would contribute negatively to aroma profile.

• Isomerizes hop-derived alpha acids to increase solubility, and contribute to bitterness flavor profile.

Kettle Reactions - Boiling

• Female flowers are found in the axils of each bract.

• The ovaries are covered with lupulin glands.

•If flowers are pollinated, the fruit that develops will be thin-walled and will surround a single seed.

•Unpollinated flowers will not develop fully, and the entire inflorescence may lack any fertile seed.

“Copper” CW 2 – Fuller, Smith & Turner Brewery, Chiswick, London, England

Isomerization of Humulone

HOHO

R

OOH

α-acids – (humulones)

iso-α-acids (*both cis- and trans- forms)

H

OHOHO

R

OO

**

“Bittering Components”

Isomerization

occurs during the

boiling process

Brewing MicrobiologyBrewing Microbiology

• Primary fermentation organisms are yeasts of genus Primary fermentation organisms are yeasts of genus SaccharomycesSaccharomyces: :

S. cerevisiaeS. cerevisiae – ale strains; wine strains, baking – ale strains; wine strains, baking strainsstrains

S. delbrS. delbrüückiickii – weizen beer strains – weizen beer strainsS. carlsbergensisS. carlsbergensis (syn. (syn. S. uvarumS. uvarum) – lager strains) – lager strains

• Highly diverse range of yeasts and bacteria reported from Highly diverse range of yeasts and bacteria reported from spontaneous lambic beer fermentations: spontaneous lambic beer fermentations:

Yeasts: Yeasts: BrettanomycesBrettanomyces, , Kloeckera, Saccharomyces; Kloeckera, Saccharomyces; Bacteria:Bacteria: Citrobacter, Enterobacter, Hafnia, Klebsiella, Citrobacter, Enterobacter, Hafnia, Klebsiella,

Pediococcus.Pediococcus.

• Certain beer styles include fermentation with anaerobic lactic Certain beer styles include fermentation with anaerobic lactic fermentative organisms: e.g. fermentative organisms: e.g. LactobacillusLactobacillus

• Contaminant organisms (e.g. Contaminant organisms (e.g. PediococcusPediococcus) found almost ) found almost ubiquitously in brewery settings; constant screening to avoid ubiquitously in brewery settings; constant screening to avoid spoilage.spoilage.

Anaerobic Fermentation:Sugars to CO2 and Ethanol

CC

CC

CC

CC

CC

OO

HHHH

HH

HHHH

CHCH22OHOH

HOHOOHOH

OHOH

OHOH

pyruvicacid

glucose H3C-C-C-OH

O O

carbondioxide O=C=O

H3C-CH=O

acetaldehyde

H3C-CH2-OH

ethanol

++

2X2X

Workhorses of Brewing Fermentation:

Yeasts.

• Yeasts are unicellular ascomycete fungi with no (or sporadic) sexual stages.

• Reproduction occurs primarily through asexual ‘budding’ or clonal growth through simple mitotic cell division.

• Capable of aerobic and anaerobic metabolism.

Traditional Fermentation:Open System

• Open top fermenters protected by a blanket of carbon dioxide during fermentation.

• Typical of ale fermentations which are “top fermenting”.

• Sanitation is a primary concern; contamination risk is high.

• Modern systems utilize closed fermentation.

Modern Fermentation – Closed systems

Redhook Brewery, Woodinville, Washington

Conditioning

• Beer requires a period of post-fermentation conditioning.

• Flavors “mature” through this conditioning period.

• If conditioning is done “cold”, it is referred to as ‘lagering’.

• Carbonation usually also associated with the conditioning process.

Packaging: Bottling• Often done at high rates.

• Beer condition improved if air is excluded.

• Must proceed in a sanitary and efficient manner.

• Also must avoid high temperatures.

Shepherd-Neame Brewery, Faversham, Kent, England

Packaging: Kegging

• Traditional kegs made from wood.

• Modern kegs are stainless steel, typically 15.5 US gallons.

• Maintained in cold condition, or beer is flash pasteurized.

• Dispensed with carbon dioxide system.

Stoudt Brewery, Adamstown, Pennsylvania

Beechwood Aging at Anheuser-Busch

“Evolution” of Beer Styles1

1Adapted from M. Jackson, 1988

Witbier

Weizen

Berliner Weisse

Belgian Lambics

Stout

Porter

Brown Ale

India Pale Ale

Barley Wine

Altbier

Belgian Ale

Trappist Ale

Cream Ale

Pale Ale - ESB

S. delbruckii

S. cerevisiae

S. carlsbergensis

pure strain

lactic fermentation

spontaneous fermentation

wheat beers

roasted barleydark malt

Ales

+ corn

pale malt

increasing hops & gravity

Lagers

“bottom-fermenting”

“top-fermenting”

Pilsener

Dortmunder Export

Vienna

Märzen/Oktoberfest

Munich

Bock

Belgium/NL

Germany

UK

US

+ hops

+ malt

+ malt & sugar

Beer SummaryBeer Summary

• Beer is among the oldest beverages made Beer is among the oldest beverages made by humans, and has persisted through by humans, and has persisted through thousands of years of human development.thousands of years of human development.

• Both barley and hops require extensive Both barley and hops require extensive post-harvest processing before the plant post-harvest processing before the plant material becomes suitable for use in the material becomes suitable for use in the brewing industry.brewing industry.

• Beer is a multi-faceted beverage with a rich, Beer is a multi-faceted beverage with a rich, intimate history involving plant intimate history involving plant domestication, selection, and breeding.domestication, selection, and breeding.

• Beer is one of the “universal” beverages Beer is one of the “universal” beverages found in most societies around the world.found in most societies around the world.

Cheers!