After the last post there was a bit of discussion about this method.
One big question was: “Why break and then skim? Why not just skim?”
This seemed like a pretty good question to me, so today I decided to do a few quick tests.
I took two identical presses, the same dose of coffee, the same brew water, temp and time and then after 4 minutes broke and cleaned one, and just cleaned the other. I then tested out the TDS in each cup of coffee.
A TDS meter is useful, but limited. It will tell you how much is dissolved in the water and nothing more. Here I wanted to see if one cup was stronger than the other. It turns out one was – and by quite a significant percentage.1
The broken and stirred cup was stronger, usually by around 0.2%. This doesn’t sound like much but when you do the maths backwards you find that it is a swing of about 3% of the ground coffee solubles extracted into the cup.
I want to do some more tests on this, and I want to do some blind cupping of it as well. However it would seem that if your grinder produces a lot of fines, and when making press coffee it seems to easily overextract then I would just skim, opposed to breaking and skimming. It could be that a different dose and steep time could yield better results. I am waiting for Mark Prince’s article on his press technique because I know that while he skims but doesn’t break he does use different parameters. It may be that one style might highlight a certain coffee better than another, who knows – I am just interesting in learning more about all this.
- It should be noted that I haven’t done this experiment enough times for it to be seriously useful – if anyone out there with a TDS meter wants to contribute then please do! [↩]