Coffee Data Science
Dump Transitions for Blooming Espresso Profiles
Could a quick dump work better?
In developing the Pump & Dump profile, I have made great use of a dump step before a bloom step. So I started to think if this thinking could help for blooming profiles that are more common like the Blooming and Allongé Blooming profiles.
Usually, when I am moving on to the next step, I want it to happen quickly. I have a manual move on after step 16 in this example of a Pump & Dump variant. The aim is to move on once the filter is covered with coffee, but typically, by the time the transition happens, more coffee than desired has come out.
Looking at this step for this profile, the time to transition was key.
I can zoom in a bit to better understand it.
Then I took some statistics on this step. A dump transition happens faster and pushes through less water.
For my purposes, I need a quick transition. Will this work for blooming profiles?
The main difference in bloom phase between the Blooming and Pump & Dump profile is flow rate of the bloom phase. For Blooming profiles, it is usually 0 ml/s or 0 bars of pressure. For Pump & Dump, it is 0.5 ml/s or some slow flow rate. I determined this was key in the flow rates for the Kim Express, and I have tried to improve on it without success.
Blooming Profile Revised
I modified blooming profiles to add a dump step and move on once flow is under 0.1 ml/s.
This causes a faster fall to the bloom phase and shortens the profile a little bit.
I took four pairs of shots, and I expected to see an improvement in quantitive metrics. I used TDS, EY, and IR to evaluate performance. For coffee, I used 3 month old coffee mainly for experiments as it is mostly degassed.
Total Dissolved Solids (TDS) is measured using a refractometer, and this number combined with the output weight of the shot and the input weight of the coffee is used to determine the percentage of coffee extracted into the cup, called Extraction Yield (EY).
Intensity Radius (IR) is defined as the radius from the origin on a control chart for TDS vs EY, so IR = sqrt( TDS² + EY²). This metric helps normalize shot performance across output yield or brew ratio.
There wasn’t a clear winner. Two of the profiles were Blooming and two were Blooming Allongé. The data shows dumping had a negative effective. It could be tied to water contact time because the dumping profiles finished faster.
I test and re-test the components of my profile to better understand why they are working because that leads to insights to improve my shot. Some times, the improvement is just because I would like an improvement, or in this case, there is evidence that a dump transition would not benefit traditional blooming profiles.
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