Coffee Data Science
Vibration Tamping for Espresso
AKA Tamped on Squid
Teddy has been talking about tamped on squid for espresso for a year now, and he finally revealed the mechanism. It boils down to placing the basket on a vibration platform while tamping it at the same time. Previous work like the Vibration Distribution Technique (VDT) did something similar without the tamping.
So I wanted to see before the device comes out, how such vibrations could affect finer particles. Does it causes fines to migrate to the bottom during vibration?
I simulated his setup using a vibrating back massager, a rubber base and a tamper. It is clear to me why one would make a full rig like Squid 🦑 because it was challenging to keep the basket on there. I used spent coffee grounds for this test.
I did some vibration, took a core sample, and then I vibrated some more to see how the hole fills in.
I did another test with sifting where I used a 500um screen to sift coffee. I put the coarse particles on the bottom and the fine on top. From these tests, I pulled some core samples to measure the distribution of coffee particles to understand how they change.
Regular Coffee Distribution
I compared the regular distribution with the top, middle, and bottom of a core from the same coffee after vibration (Z indicates using the tele lens which was calibrated using the wide angle lens of an iPhone). The bottom saw an increase of finer particles, and the top saw an decrease of finer particles.
Personally, I’m curious if using enough vibration for long enough could sift the coffee according to the particle size and basically cause a sifted staccato laying without sifting.
Sifted Coffee
As a reminder, this experiment involved sifting coffee into two layers with the coarse grounds on the bottom and the fine grounds on top.
The result of vibration is that the top layer stays about the same, the top middle has some shifts, but there is an overlap with coarser particles. The middle bottom has a similar issue. The bottom though does gain finer particles.
I vibrated this setup more, and the bottom continued to gain finer particles, but the finer layers were not quite gaining coarser particles.
This experiment was challenging because vibrating a filter basket isn’t straightforward. Having a tool like Squid 🦑 will help better understand the effects and go beyond one step better than regular distribution. I think the bigger win with the tool could be automated reordering of the particle distribution.
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