Blooming was inspired by pour over drip coffee brewers... releasing CO2 and allowing the grounds to be fully saturated.
It's a great profile for extracting sweetness, esp from lighter roast coffee that is really acidic.
It's a high extraction profile that is also very forgiving.
A big thanks to Scott Rao for all his work.
This profile is exciting from an experimentation point of view as it open's a pathway for extracting
more coffee from less.
I don't usually use a dark roasts with this profile (unless I want my coffee bitter).
I think it's better with light to medium roasts.
You can replicate this on a lever machine.... or any machine that allows you to control flow.
A machine without a OPV (over pressure valve) or a way to override one is an advantage.
This profile has a very long initial pre infusion stage before a flow controlled pressured stage.
Firstly, make sure you grind finer than you would usually for espresso.
I've seen filter paper placed below and above the tamped coffee cake.
These two pieces of paper are supposed to do two things:
1. reduce channeling (top paper) and help dispersion of water over the cake.
2.speed the flow (bottom) as those particles might clog the portafilter. ???
These are just theories so experiment to you heart's content.
Maybe I want to decrease the flow and those fines clogging the portafilter might be a good thing. ...so I sometimes experiment with just the top paper?
I don't like using paper anyway (for environmental reasons) so am experimenting with a puck screen and not using a lower paper filter.
Maybe try using two metal puck screens ?
Method:
1. Ramp the pressure up
to 4 to 6 bar over 10
secs.
Once you hit about 5
bar stop pushing on
your lever (if you're
using a lever machine).
2. You should have let go
of the lever.
This is the blooming
stage where the flow
drops to zero.
The pressure will also drop to zero as water is absorbed into the puck.
If you're using a lever you may see some drops of coffee falling into the cup.
This is OK.
This blooming stage will all take about 10-40 secs.
The water should just sit on top of the puck (in "suspended animation").
The Decent app recommends using a blue-tooth scale to keep track of how much dripping into the cup there is before the ramp stage.
They think that about 8 grams of total dripping, (within 2 grams), gives the best tasting results.
3. After the blooming stage is finished, ramp the pressure up (you don't want to reach 8-9 bar).
Just try to maintain flow at 2ml/sec. Between 2-4 bar should be sufficient.
I like to aim for a 1: 3 ratio.
Or go even longer.
Pull 1:4 or even 1:5
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I like to see this profile more as a flow profile rather than a pressure profile but of course pressure & flow are hard to separate.. It has 3 stages:
1. Pre-wet stage - 25sec - 4g/sec
2. Bloom stage - 30sec - zero flow
In this stage we stop the flow but try to maintain some (passive) pressure.
This is hard to achieve on most automatic machines (not the Decent, Gaggimate or lever machines)
since when you stop flow, you stop pressure (the OPV opens on most machines).
It's important to have some remaining passive pressure in the system to maintain
puck integrity.
3. Brew/percolation stage - ramp up to 2g/sec and maintain for 25 secs
This is a shot from my modified Rancilio Silvia (Gaggimate mod)
1. 4g/s for 7 secs
2. zero flow for 30 secs
3. 2g/s for the rest.
My aim was a 1:3 , 1:3.5 ratio.
18g in, +54g out.
I manually stopped the shot at 60secs when I reached 62g.
I need to grind finer. Dripping too much in stage 1.
and the pressure never rose above 1 bar in stage 3.
I don't have a TDS meter so can't give a scientific measure of the extraction levels, but it tasted strong. Quite pleasant, sweet, a bit of acidity. not bitter.
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