this a non-issue, some purists argue that
Reinheitsgebot’s list of four approved
ingredients does not include external gas.
Today, most American craft brewers
who ferment under pressure do so with
lagers. However, some do find success
spunding ales. While fermenting an ale
under closed conditions can create
dangerously high pressure levels, a properly
functioning spunding valve should stop
these levels from rising to an unsafe point.
To reduce capex investment, brewers
generally choose tanks that are rated for
lower operating pressures, though they
can purchase fermenters rated for higher
internal pressures to support such robust
natural carbonation.
How to dry-hop wort in a
closed system?
How are hops infused into a fermenter
when it’s sealed? Hook a hop-filled brink to
the fermenter and set it to a psi lower than
the tank, for example, five psi to the tank’s
eight. This lets the brink suck in wort, to
which hops can be added to create a hop
slurry. Now, set the brink to 12 psi so the
slurry pushes back into the fermenter. Voila,
dry-hopped beer.
How are off-flavours cleaned-up?
Epoch shaves days off her brew by letting
the yeast clean up diacetyl and other off-flavour-
producing compounds during
the last third of fermentation instead of
waiting until it’s done to give the beer a
diacetyl rest. To do so, she removes the
cooling jacket and lets the temperature
free-rise.
“After the yeast has aggressively
reproduced, there’s not enough food left
to create a bunch of off-flavours,” she said.
“So when you cut off that temperature
control, as a last resort they’re eating
those unwanted chemical compounds.”
What precautions should be taken
when spunding?
As detailed earlier, fermenting under
pressure can prove dangerous if brewers
don’t pay close enough attention to the gas
build-up in the tank. As such, here are two
important precautions to ensure spunding
valves work as designed.
1. Don’t start spunding too early, as
krausen can form (primarily in
ales) and clog the valve.
2. Some spunding valves measure in
bar even though many American
brewers calculate pressure in
psi. Gauges that display both are
available, but if a brewery’s don’t,
do conversions carefully. With
one psi equivalent to 0.08689 bar,
Epoch said, “The difference is
staggering. You want to be under
one bar, maximum.”
BrewMonitor can help brewers
understand the effect of different
carbonation methods and get the best
results. The BrewMonitor System enables
craft brewers to live-stream dissolved
oxygen, pH, gravity, pressure, internal/
external temperature and conductivity
data to any smart phone, tablet or desktop
computer. It also sends instant alerts if a
fermentation’s metrics go out of range. It
helps increase efficiency, save money and
improve batch-to-batch consistency.
This article was originally published on
Precision Fermentation’s blog and is
reprinted here with permission.
F E R M E N TAT I O N
While fermenting an ale under
closed conditions can create
dangerously high pressure levels,
a properly functioning spunding
valve should stop these levels
from rising to an unsafe point.
Larisa Kravets/123rf
40 § POURED CANADA § www.poured.ca
/www.poured.ca
