My plan in this post is to focus on what comes out of a KafaTek Monolith Conical grinder, in particular a Gen2 (production run #10) model.
So...I was crazy enough to purchase a Kriuve sifter with a six screen set to look at what's coming out of this grinder fitted with 68mm TiN coated burrs rotating at 120rpm, designed by KafaTek (Denis). I was hoping to compare the particle size distribution (PSD) of my coffee to the work done by the Socratic guys, who have done some excellent work in the area of PSD (using laser light scattering detection) on several grinders including the MonoCon. When I started playing with the Kruve, the wife said, "What's that thing?" I said, in mad scientist mode, "I'm going to classify the coffee grounds coming from my grinder." She said, looking at the mess... "In my kitchen!?" and "Didn't you retire from research?" "NEVER!" I said...well it only got worse from there. Sometimes in the name of science we just have to take our 39 lashes, and move on.
Did I mention...1) this thing makes a mess 2) that it does exactly what it was designed to do 3) that it makes a mess...I think I already mentioned this.
Back on topic, I found a PSD graph that the Socratic guys put together in 2017 using a Gen 1 MonoCon (see below). The most interesting reveal from this graph is that the grinder with its 68mm conical burr set produces little in the way of fines (let's call the fines fraction... particles less than 200 microns), a large amount of particles in the 250 to 350 microns range (let's call this espresso optimum), and a small but significant amount of greater than 350 microns particles (we will call this the coarse fraction). So using the Kruve, will I be able to validate the Socratic findings? The answer would be yes...well sort of.
Since I only used two Kruve screens (200 and 600 microns) one can only measure three groups in this way...particles less than 200 microns (the fines fraction), particles between 200 and 600 microns (near optimum for espresso), and particles greater than 600 microns...( the coarse fraction). I decided for now not to run replicates on this experiment because of the messiness (and the wrath of wife), but to run the experiment at three grinding levels hoping for a logical trend...and of course drink the results. In the end this little experiment proved that; 1) the Kruve sifter can reveal differences in PSD upon grinding, and 2) the KafaTek Monolith Conical grinder produces coffee grinds that are very low in fines (<200 microns), high in optimum particles (200-600 microns), with a trailing coarse fraction (> 600 microns). The particle size fractions I captured matched up well with the curve from Socrates...so I'm happy about that (see results below). Taste wise, a grind setting of 5, even down to 4, has been great for this coffee (Kaldi's Espresso 700). It's well balanced with excellent sweetness with just the right amount of acidity. At a setting of 6, this coffee was a little on the "thin, transparent" side, and at a setting of 3 it was like drinking mud! I performed one test using a totally different coffee (Kenya AA) just to see if the PSD curve would be radically different...it wasn't. Data Table for Kaldi's Espresso 700:
...<200microns / 200-600microns / >600 micronsGrind Setting
..... 6__2.0% 76.2% 21.8%
..... 5__1.0% 78.4% 20.6%
..... 3__2.0% 81.1% 16.9%
.....6(Kenya AA) 1.8% 76.1% 22.0% Micrographs of fines, optimum, and coarse particles at 50X
I hope you enjoyed the write-up, and as usual, all comments are welcome!