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alcohol -What is it?
a class of molecules that have an –OH group
methanol- 1 carbonethanol- 2 carbonspropanol- 3 carbons butanol- 4 carbonspentanol- 5 carbons
alcohol -Where does it come from?
aerobic respiration - requires oxygen - 36 ATP per glucose molecule - low energy waste products, H2O and CO2
alcoholic fermentation
lactic acid fermentation
anaerobic respiration
fundamental metabolic processes:extracting energy from sugar
glucose
alcohol -Where does it come from?
anaerobic respiration = fermentation
- extraction of energy from glucose without oxygen
- only 2 ATP per glucose molecule
- very inefficient, high energy waste products
- lactic acid
- ethanol
alcohol -Where does it come from?
We’re only concerned with alcoholic fermentation
- many fungi and bacteria can perform alcoholic fermentation; fairly common amongst microorganisms
- Saccharomyces cerevisiae brewer’s and baker’s yeast
water + sugar + yeast + time = alcoholic beverage
- alcohol is a byproduct of yeast metabolism, it’s a waste product, it’s yeast poop
alcoholic beverages
the source of sugar, the process, other ingredients, and geographic origin are used to classify types of alcoholic beverages
In other words, why are there so many types of alcoholicbeverages?
What makes beer beer?
alcoholic beverages -Sugar source
beer
wine
sake
mead
cider
pulque
masato
chicha
cyser
birch beer
grains
grapes, fruit
rice
honey
apples
agave sap
manioc root
corn
honey and apples
birch sap
whiskey, vodka, gin
brandy, grappa
awamori
calvados, apple jack
distilled mead
tequila
??
bourbon
alcoholic beverages -Process
beer
wine
sake
mead
cider
pulque
masato
chicha
cyser
birch beer
grains
grapes, fruit
rice
honey
apples
agave sap
manioc root
corn
honey and apples
birch sap
whiskey, vodka, gin
brandy, grappa
awamori
calvados
distilled mead
tequila
??
bourbon
alcoholic beverages -Process
the process
- wines typically have nothing added to them, just juice; not cooked, but cider too
- sake is made with different yeasts than beer, different process
- chicha is made with different yeasts than beer, different process
alcoholic beverages -History
geographical factors:
- where each type of sugar source was first domesticated
- degree of isolation
- local names/traditions lead to divergence of beverages
alcoholic beverages
today, beer is usually made with four primary ingredients:
(1) water
(2) malted barley
(3) hops
(4) yeast
Modern beer also has a very particular process of production
the beer we know today has only been around since the mid 1600s
brewing beer
cultivatemaltmillmashspargeboilhopfinecooloxygenatepitchfermentagefinefilterpackageenjoy
HISTORICAL DISCLAIMER
brewing beer -Cultivating
What are grains?
- Angiosperm, grasses, Poaceae, (flowering plants)
- the fruit of the grass, but starchy not sugary
- Hordeum vulgare, barley
brewing beer -Malting
but yeast can’t use starch to live, thus they can’t makealcohol from starch
- this is not an issue in wine making, why?
- a big difference in process
brewing beer -Malting
need to convert the starch to sugar so that the yeast can usethe energy stored in the starch to make alcohol
- what is fruit for? why do plants have fruit? why do
grasses have grains?
brewing beer -Malting
no living thing (or very few living things) can use starch directly to get energy
- most living things need to convert starch to sugar first
- yeast can’t do it
- some fungus can
- plants can
- humans can
brewing beer -Malting
brewers borrow the plant’s ability to convert starch to sugarby tricking them into thinking they’re growing
this is malting
soaksproutspread and germinatekiln
α-amylaseβ-amylase
also in human saliva
brewing beer -Malting
malting is also where much of a beer’s character is determined
- type of barley used
- 2 row vs 6 row- color, protein- American- Canadian- English -Maris Otter- Scottish –Golden Promise –terroir? - German- Belgian
- malting method
- floor malted- machine malted- kilning fuel –peat, wood smoke
brewing beer -Malting
kilning
- temperature
- length
- moisture content
types of malt
- base malt- biscuit- Vienna- Munich- aromatic- crystal- chocolate- black patent- roasted barley
brewing beer -Milling
need to expose the starch
don’t want to pulverize the grains, need to keep the husks intact for the sparge or else big trouble –peated malt
brewing beer -Mashing
converting starch to sugar by activating a suite of enzymes that were created by malting the grain
mix milled grains with water in a mash tun
water/grain ratio, temperature, water chemistry all affect how the starch is converted
low temps, 140°F = lots of glucose
high temps, 160°F = lots of complex sugars, dextrins
brewing beer -Mashing
some beers use unmalted grains in the mash such as corn, ricewheat, the big 3 use a lot of these adjuncts
- how could this be a problem? how to remedy the problem?
brewing beer -Sparging
how to separate the crushed grain from the sweet liquid, the wort, that will become beer?
- straws
- grain bed, husks
lauter tun (usually mash tuntoo)
brewing beer -Sparging
recirculation –recirculate the wort until it is clear
parti gyle –do one mash, then drain all the wort off, add more hot water, do another mash, drain all the wort, continue until all sugars are gone
- usually results in two or three smaller batches of beer that range from strong to medium to weak
sparging –do one mash, begin to drain the wort off and as the wort level falls, add hot water, sparge water, to rinse the sugars from the grains, continue until all sugars are rinsed
- usually get one big batch of beer that is one strength, weaker than first runnings of parti gyle but stronger than second runnings
brewing beer -Sparging
What do I mean by strong and weak wort?
original gravity –the density of the wort before fermentation determined by how much sugar is dissolved in the wort
high gravity = lots of sugar = high density
lots of sugar = potential for lots of alcohol
brewing beer -Boiling
wort –the clear, sugary liquid that is collected during run off, also called sweet wort
collected in the boil kettle or just kettle
why boil?
- “sterilize” wort
- coagulate proteins
- concentrate sugars
- extract hop oils
brewing beer -Hopping
Humulus lupulus
a tall, non-woody vine that dies back to the ground every winter, perennial, Cannabaceae family, sister genus to hemp
female flowers produce cones that bear lupulin glands which contain many different oils that contribute bitterness, flavor,and aroma to beer, also bacteriostatic, used to balance sweetness of malt
must be boiled vigorously to extract the oils
brewing beer -Hopping
many different varieties, typically grouped by region of origin, American hops most distinct
- England
- Fuggles - East Kent Goldings - Target - Challenger
- Germany
- Spalt - Tettnanger
- Hallertau
- United States
- Cascade - Simcoe - Chinook - Magnum
- Czech Republic
- Saaz
brewing beer -Hopping
hops are just one type of spice
others still used today
- orange peel- coriander
more historical
- rosemary- spruce tips- myrica gale- wormwood- mints
brewing beer -Fining
fining –the addition of material to beer or wort that aids in the clarification of the wort and beer
during the boil, carrageen in Irish Moss helps pull proteins out of solution
brewing beer -Oxygenating
even though fermentation is an anaerobic process, we want the yeast population to be large enough and strong enough to havea healthy fermentation
brewing beer -Pitching
pitching –the addition of yeast to the cooled wort, also called bitter wort now
until very recently, 1940sand 50s in England, mixedcultures of yeast were pitched
pure culture fermentation, only one type of yeast, wasnot adopted until 1890s in Europe, now almost universal
1/1000 of a millimeter
brewing beer -Yeast and fermentation
fermentation –the period of time from pitching to complete attenuation (also the biochemical process that makes ATP without oxygen)
attenuation –the degree to which the yeast convert sugar to alcohol and CO2
original gravity –density of the bitter wort before pitching, many sugars dissolved in the wort
final gravity –density of beer after fermentation is complete, depends on yeast strain, mash
temps
brewing beer -Yeast and fermentation
stages of fermentation
primary fermentation -where vast majority of attenuation occurs, 3-20 days
lag phase –yeast are acclimating to wort, little obvious activity, 2-24 hours
aerobic phase -yeast grow very rapidly, population increases exponentially, consumes much of the sugar, much attenuation occurs here, consumes oxygen, obvious activity, 1-5 days
anaerobic phase –yeast begin to ferment the sugars left in the wort, activity slows, 1-15 days
brewing beer -Yeast and fermentation
Saccharomyces cerevisiae
sacchar- sugar (saccharide, saccharine)
myces- fungus (ancient Greek)
ceres- Greek goddess of agriculture? (cereal)
Saccharomyces carlbergensis
Carlsberg- Danish city where lager species was
first isolated
Saccharomyces cerevisiae -ale yeast –warm fermentation, between 65-90°F (avg 70°F), typically more character than lager strains, less attenuative, short fermentation and aging, as short as 5 days from grain to glass, top fermentation
brewing beer -Yeast and fermentation
S. uvarum (S. carlbergensis) –lager yeast –cool fermentation, between 48-55°F, typically cleaner than ale strains, more attenuative, long fermentation and aging, primary: 20 days, secondary or lagering period, at least 14 days, bottom fermentation
brewing beer -Yeast and fermentation
many different strains within each species, 1000s of strains
- in addition to alcohol and CO2, different strains contribute different flavors and aroma
- Belgian strains: lots of character, fruity, clove, can be very attenuative even though they’re ale strains
- English strains: lots of character, fruity, bready, not attenuative, ale strains
- German strains: mostly lager strains, clean, attenuative
- American strains: both ales and lager, typically clean
brewing beer -Yeast and fermentation
spontaneous fermentation –no yeast is added “by hand”; Belgian lambic style beer; many different
microorganisms
brewing beer -Yeast and fermentation
brewing beer -Aging
after fermentation, beer is generally racked from one vessel to another, from the primary fermenters to the aging tanks
beer is aged for a couple reasons
- to complete attenuation
- *for proper flavor development, yeast reabsorb certain molecules, chemical reactions occur etc.*
- for the beer to clear
aging also known as secondary fermentation
some ales not aged at all, Upland Wheat, most aged only 1-2 weeks, very strong ales aged up to a year or more
brewing beer -Aging
lagering –a long period of cold aging that is normally required when using a lager strain, lager = to store
lagering takes at least 2 weeks, usually a month to 6 weeks, the stronger the beer, the longer the aging
brewing beer -Fining
at this stage, finings are added to encourage the yeast to drop out of suspension, but also proteins and other large,haze forming molecules, both a physical and electrical process
isinglass and gelatin are popular finings, some strict vegetarians object to its use, swim bladders and bones etc.
usually used in British breweries, synthetics are becoming more and more popular such as polyclar and DE
brewing beer -Filtering
beer is typically filtered immediately before packaging
filtering removes all yeast and other microorganisms, can also remove proteins and other large molecules
has an effect on packaging because filtering impactsstability of the product, when stripped of large molecules, there can’t be much chemical activity in thebeer and thus it can’t change much and of course with everything living having been stripped out, nothingcan grow and spoil the beer that way
brewing beer -Packaging
cansbottleskegscasks
How to get the gas into the beer?
artificial carbonation –filter the beer and forcibly inject CO2 then package
natural carbonation
- do not filter, add extra sugar or actively fermenting wort, and put a cap on it
- filter, add some sugar AND yeast or actively fermenting wort (Sierra Nevada)