So when I first came up with the idea of journaling my trial
week at BrewDog I had intended on writing an entry after each shift. Unfortunately
one of the first things I learned about being a brewer is that time is valuable
and more often than not your only free time is spent sleeping in preparation
for your next shift. So instead of this entry describing my first shift it will
be describing my first three.
My first shifted started on Monday afternoon at 14:00 and
was busier than I imagined. At the moment BrewDog runs a system comprising of a
hot water tank (~70 hectolitres) a mash tun (~50 hl) and a copper (~65 hl) as
well as 23 fermentation vessels (FV) ranging from 50-200hl; A fairly standard
system for any brewery. When I arrived the contents of the copper had just been
fed into one of the FVs and so my first job was to clean the inside of the
copper in preparation for the next brew. This involved climbing into the copper
and scrubbing the walls and coils to remove the residue from the previous boil.
The copper that BrewDog uses is powered by a large pipe about 15cm in diameter
that is filled with burning gas during the boil; I can only assume this method
is used because it is the most cost efficient way to boil 5000 litres of wort. After
cleaning and reassembling the copper it was time to prepare the next brew.
Because of the high demand for BrewDog beers, coupled with
the fact that they have only one brew system to supply 23 FVs, the brewery
never sleeps. When one brew is finished the next batch of ingredients is laid
out and as soon as the mash tun and copper are clean the next brew is started.
My second task was to mash-in on a batch of Dogma. Mashing-in is the first
stage in the brewing process where malt (grains) and water are fed into the
mash tun at a carefully controlled rate. The grains are left to soak in water
that is heated to between 64-70C depending on the recipe being used. During
this process the fermentable sugars contained in the malt are released into the
wort. The recipe that we were using for Dogma called for ~1100kg of grains that
were fed in 25kg bags into a pump that mixed them with water and carried them
into the mash tun. After 105 minutes of soaking the grains we began transferring
the wort into the copper.
The transfer of the wort from the mash tun to the copper
takes about three hours. The transfer is done this slowly because of the manner
in which the grains distributed in the tun. When the grains are soaking in the
mash tun they are mixed with water in a ratio of 2.5ml/g, a ratio that
maximises the efficiency of sugar extraction while minimising the volume of the
mash. The grains are suspended in the water and when the transfer begins
further water (heated to about 80C) will be added to the mash tun very slowly
in a process called German sparging, while at the same time water is drawn out
the bottom of the tun at a slow rate. The process is done slowly to maximise
the amount of time that the water is in contact with the grains and the rate at
which the water is carried out of the tank must very closely match the rate it
is fed in. If water is drawn out of the tank too quickly it can cause the
grains to compact against the bottom of the mash tun and the mash will become stuck.
Four times during the three hour transfer samples of the wort
are drawn off and cooled. We then measure the temperature, pH, gravity and
total volume of the copper at each stage. The gravity of the wort is a measure
of how much fermentable sugar is dissolved in the liquid, and is measured using
a hydrometer. A hydrometer looks like a thermometer with a weighted bulb on the
end and when submerged it will find a buoyancy point that depends on the
density of the wort. The hydrometer reading is adjusted based on the temperature
of the wort and this value allows us to determine if the post-fermented beer
will have the alcohol content that we are aiming for. Once the transfer is
finished the copper is set to boil for an hour. All in all, the above process
took the duration of my shift on Monday (until 22:00), and I packed up for the
day just as the finished wort was being sent through a heat exchanger for its
transfer into a FV.
After my shift I sat down in the staff area with a few of
the other employees from the bottling line. BrewDog hooks up a kegerator for
the staff to use once they have finished their shift and I enjoyed a fantastic
pint of Imperial Lager; a beer that I only found out after my pint was 9.9%. It
made a brilliant night-cap, and I managed to stumble home for a few hours’
sleep before staring at 5:45 the next morning.
After a terrible 4 hours’ sleep I woke at 5:10 on Tuesday morning
feeling like I had been hit by a train, a feeling that has not subsided yet. Arriving
at the brewery at 5:45 I walked in just in time to mash in for the second time,
this time on a batch of Hardcore IPA. And so by 6:30 in the morning I had
already lifted 1300kg. Once we mashed I started a rota of ‘tank-actions’. Tank
actions are several different jobs that need to be carried out on fermenting
beer to ensure its quality after fermentation. They involve de-yeasting,
de-hopping, and rousing. Because the FVs are so large fermentation that would
normally produce small amounts of dead yeast and enzymes produce several
hundred litres a day (I took 1050 litres of yeast out of a 200hl tank). This
sludge from the bottom of the tanks needs removed at regular intervals so the
beer is semi-clear when it comes time to filter and bottle it; this is
de-yeasting and de-hopping. Rousing involves pumping CO2 into the
tanks of beer for 2 minutes to do just that; ‘rouse’ the beer.
After the tank actions were finished the mash tun used for
the Hardcore IPA was ready to be emptied. At very large breweries this is an
automated system, but at BrewDog cleaning the mash tun involves climbing inside
it and shovelling out the spent grains. Because of the high specific heat
capacity of water (4.18 Jg-1K-1 compared to 1 Jg-1K-1
for Air and 0.45 Jg-1K-1 for Iron) the moisture remaining
in the grain had not cooled much from the temperature of the mash and sparge
liquor. I stand by the statement that I have never been so hot as when shovelling
~1500kg of damp grain in temperatures ~65-80C (149-176F).
Today passed much like the previous two days. I arrived this
morning, again at 5:45, just after the night shift had mashed in on another
batch of Hardcore IPA. So I completed the tank actions and waited to shovel out
the mash tun again. The last thing I did before I sat down for a pint of Hardcore
IPA this afternoon was to prepare the bags of malt for a batch of Black Ginger
to be mashed in by the afternoon shift.
I’ve been passing the time (when I am not at work and not
sleeping) at ‘The Elizabethan’, a pub located a 5 minute walk from the B&B
chatting with the bartender about starting work at the brewery; A very nice man who just brought me a pint of
Punk IPA as a welcome to Fraserburgh.
Link to Diary of a Brewer: Trial Week Part 2
Don't let anyone tell you that there isn't science involved in brewing beer!
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