Preparing For Fermentation
Before we ferment, we
take a hydrometer reading. This will tell us
our original, or starting gravity of the beer.
This is a measurement of the density of the
wort, which should be much higher than water
(1.000) because of the high concentration of
malt sugars. We take a sample of the brew with
a wine thief or siphon hose that has been pre-sanitized,
and fill our test jar with the sample. We place
the hydrometer into the sample jar and give
it a quick spin to release any bubbles that
may be trapped on the bottom of the hydrometer
that could affect our reading. To properly
read the hydrometer we look at the line between
liquid and air at eye level. The bottom of
this line is where we take our reading. Our
starting gravity reads 1.048, which is right
on target for our Red Ale.
Now that our yeast has
been added, it is time to seal the fermenter.
Because we are using a 5 gallon carboy as our
primary fermenter, we will need to set up a
blow off tube. The blow off tube will allow
CO2 and foam to escape the fermenter
without letting any airborne particles in.
Our blow-off system (pictured left) uses a
sanitized rubber stopper and a sanitized 3'
length of food grade plastic tubing. The end
of the tubing is placed in a container of sanitizing
solution to create a closed system.
If we used a six gallon
carboy or bucket, a blow-off tube would not
be necessary, because a larger container would
allow enough room for the foam produced during
the early stage of fermentation. In this case,
we would close the fermenter with an airlock
(pictured below, left). The airlock is filled
halfway with sterile water or a neutral sprit
such as vodka. This allows escaping gasses
to bubble through the airlock without allowing
any unwanted airborne organisms into the fermenter.
We place our fermenter
in a cool dark place, that has a fairly constant
temperature of 60- 70 oF. If our
chosen location is not dark, we will wrap a
towel or heavy cloth around the fermenter to
prevent light from hitting the fermenter and
to provide some insulation. It is especially
important that strong light does not reach
the fermenting beer as this can affect the
flavor of the finished beer, causing what is
often called a "cardboard" taste.
12 to 24 hours later,
our beer is actively fermenting. A thick layer
of foam has formed on top of the beer- this
is called the kraeusen. Also, because we used
a glass fermenter, we can see the brew actually
moving in a churning, swirling motion. It is
good that we used a blow-off tube, because
the foam is starting to get pushed out of the
fermenter. If we had used an airlock, it could
get clogged, causing a buildup of pressure
that could blow the cork out of the fermenter
or even break the glass carboy.
3 to 5 days later, the
kraeusen has all but disappeared and the fermentation
activity has slowed considerably. It is time
to transfer the beer to a secondary
fermenter. Although this step is not necessary,
it will produce a more complete fermentation,
and a beer with a cleaner taste and appearance.
We will siphon the beer into the secondary
fermenter, to prevent air from being mixed
into the beer. Siphoning is not too hard to
do once to get the hang of it- see the next
for a good trick for doing this.
After transferring we
put an airlock on the fermenter and allow the
fermentation to complete, for another 5 to
8 days. Our total fermentation time will be
8 to 14 days. We know the fermentation is complete
1. The airlock bubbles less
than once every 60 seconds.
2. We take a hydrometer
reading and it is in the range of the final gravity
for the recipe we have made (1.012 to 1.016).
The next day we take another hydrometer reading,
and it has not changed. The hydrometer reading
is lower at the end of the fermentation because
the sugar molecules (heavier than water) have
been converted to alcohol molecules (lighter
than water) and CO2, which has been
pushed out of the fermenter.
3. The beer is almost clear;
the top to thirds of the fermenter are relatively
clear, but the bottom third is still somewhat
cloudy, which is O.K.