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Home Brewing
How you can brew your own beer
utilizing chemistry!
• Beer has been brewed since the ancient
civilizations of Egypt and Mesopotamia
• Fermentation
discovered by Louis
Pasteur in the 19th
Century
• Beer has over 450 identified chemical
compounds with an acidic pH ranging
from 4-4.5.
• Beer is never at equilibrium, which
means chemistry is extremely important
to the control of reactions during the
brewing process.
Steps of Brewing
1)
2)
3)
4)
5)
Malting
Mashing
Boiling
Fermentation
Aging
1) Malting
• Soak grains and let them dry
• Allows for the formation of enzymes
(This is usually done before you buy the
grains from your local supplier)
Protein content of the barley
determines the quality of malt
• Most abundant and important protein is
Hordein
• Hordein is gluten and is the reason
people with celiacs cannot drink beer
• Extracted during the alcohol
fermentation and is responsible for the
formation of peptides and amino acids
2) Mashing
• Steeping hydrates the malt, gelatinizes
its starches, releases its natural
enzymes and converts the starches into
fermentable sugars
• For this step you will
use a Mash Tun
• Igloo coolers are ideal
• Remove the drain
spigot and add a
bulkhead fitting to
drain the wort
Add a stainless
steel braid to the
inside of your
mash tun to filter
out the wort from
the grain.
(Wort= the “grain tea water”
you get from steeping the
grain)
• Add your grain to
the mash tun, add
water that has been
heated to 160-165
F.
• Hold at this
temperature for an
hour, and then
drain the wort
• Then, infuse with
an equal volume of
sparge water,
which rinses the
grain. The mash is
then stirred,
allowed to settle
and drained again.
3) Boiling
Now add your
wort to a 7 gallon
pot and heat to
boiling
Once it is boiling, add the hops
Boiling is important for three reasons
1) It kills off any unwanted bacteria and
other microorganisms in the wort.
2) Proteins are allowed to precipitate and
then coagulate, which helps in the
formation of foam.
3) It allows for the reactions of a variety
of volatile compounds to occur.
Hops contain a class of compounds
known as a-acids, the most predominant
being:
Humulone (C21H30O5)
Because of the
harsh reaction
conditions during
boiling, a-acids will
undergo a process
known as
isomerization,
turning them into
iso-a acids.
Isohumulone
There are three types of compounds
that give hops it’s floral aroma:
Linalool
Geraniol
Geranyl isobutyrate
Now that the wort
and hops have
boiled, transfer to
a 7 gallon glass
fermenter and
shake vigorously
to oxygenate, then
add the yeast
packet
4) Fermentation
• Gives beer its alcoholic
content
• Process of transforming
carbohydrates into
alcohols and carbon
dioxide through the use
of yeast and bacteria
The sugars formed during mashing
(maltose and maltotriose)
will undergo hydrolosis and multiple
molecules of the simple sugar glucose
will be formed
• The glucose is then fermented by the
yeast, in an oxygen free environment, into
ethyl alcohol
and carbon dioxide
5) Aging
• Beer needs to be aged at a
constant temperature
because of its physical
instability.
• Small particles can form
over time giving beer a hazy
appearance.
• Use an airlock to seal the
fermenter
• One of the reasons for haze formation is
due to the formation of polyphenols
such as (+)-catechin (C15H14O6).
• Beer foam is a major indicator of the
quality of a beer
• Many chemical compounds attribute to
the foam of a beer, but the most
important are proteins formed during the
mashing step
Two qualities used to determine how well
proteins will form beer foam:
1) Hydrophobic strength. Since beer
foam forms at the top of the beer, a
strong hydrophobic character will allow
it to repel the water below, which
results in a longer lasting foam head.
2) Size of the protein. Bigger proteins
would result in a bigger foam head
being formed
Many breweries now
add unhealthy and
unnatural ingredients
such as high fructose
corn syrup. Brewing
your own beer is a fun
hobby and helps you
control what you put
in your body. Plus,
there’s nothing like
tasting your few brew!