Coffee Data Science
Cutting up the shot to learn something new
Coffee extraction happens over time, and it changes throughout an espresso shot. To better understand this, people have used salami shots. To make a salami shot, one uses multiple cups during the espresso shot. I wanted to see how my new Pump & Dump profile compared to extraction for individual particle sizes.
A salami shot can be used to measure extraction as well as better understand when different taste components are extracted into the cup.
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).
First, I pulled a shot, and I compared it to previous data I had on sifted coffee. The sifted coffee used a 4 ml/s flow control profile, so it could reduce variables. I also had separate inside fines and outside fines, and I previously found that inside fines extract incredibly fast.
The Pump & Dump extracted in the range of the inside fines <300 um, which means even the coarser particles are being extracted at a much higher rater than in the previous data.
Then I sifted the coffee, and I did a similar procedure as before with 8g sifted coffee and 13g of spent coffee. However, I didn’t separate the inside and outside fines. Only particles >500 um extract slower than the entire profile.
When we compare the Pump & Dump fines to inside fines of the 4 ml/s flow experiment, they extract at a much higher rate.
The same is true for the other particle sizes.
When looking at the percent of EY occurring, the Pump & Dump profile extracts most of the coffee in the 1:1.
This salami shot test went further to show how efficient the profile is at coffee extraction. This profile also suggests we could greatly improve extraction if we better understand the dynamics of coffee extraction. I’m particularly interested to look at how thermal energy or heat moves through a puck as this profile is also aiming to heat up the grounds with steam.
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