Playing with EK43

The other day I had the chance to play with Malkoehnig EK43, read along to find out what happened.

I conducted a small experiment to see how does the grind size impact the TDS in a filter brew, more specifically how does the marked grind sizes on an EK43 (which for the post I will call units ) impact the TDS in a V60. I wanted to know with approximately would the TDS of a filter coffee brewed using the V60 method behave if I change the grind size with a half or a whole unit.


All in all I did 5 V60 filter brews.

All the parameters of the brews were kept the same, the only exception was the grind size. The grinder was Malkoehnig EK43, all the grind sizes in this research are the ones marked on this specific model. The grind sizes are being marked with units from 1 to 11. With every brew, the grind size used was being changed with half a unit. The coffee used – washed Tipica from Ecuador, a few days old roast (don’t know how much exactly). The filter was rinsed with hot water before putting the coffee in and starting the extraction process. The temperature of the water was 92C. It was measured before pouring on the coffee grounds. The time was taken after the end of every brew.

Method – V60
Filters – paper
Grinder – Malkoehnig EK43
Water – 300ml per brew
Dose – 17g coffee

In these conditions, this is the data I collected from the brews using a refractometer to measure the TDS, Then I used MoJo to calculate the extraction rate, which is not important for this research, but I still did it.

  1. Grind size 5     – TDS 1,50% – EXT 24,84%
  2. Grind size 5,5  – TDS 1,44% – EXT 23,65%
  3. Grind size 6     – TDS 1,36% – EXT 22,49%
  4. Grind size 6,5  – TDS 1,33% – EXT 22,33%
  5. Grind size 7     – TDS 1,25% – EXT 20,65%

Now that I go back and see the data I see so many more factors that should have been taken into account. Like for example temperature should have been taken once poured onto the grounds, the temperature of the coffee slurry. I should have recorded the time properly. I don’t know if it makes sense to make assumptions now, since the data is incomplete. The overall results are as I expected them to be –  No.5, with the the coarsest grind has the lowest percentage of TDS and the opposite. But I want to know what did I do with No.3 and No.4 that the difference in the data between these two brews is so small?

Anyway, the eventual answer to my question how does the change of the grind size of the EK43 affect the TDS would be, that half a unit changes the TDS with an average of 0,05%.


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