So, the test setup will be as follows:
- coffee we're going to use Counter Culture Coffee's Toscano, a coffee I selected as something that's sweet and mellow that I expect will produce a pleasing shot from both a normal pressure profile and my 'custom' one that is vaguely lever-like.
- espresso machines will be Jon's stock La Marzocco GS3 and my GS3 modded as described in this thread.
- grinder(s) will be Jon's Mazzer Robur and potentially Paul's Robur E, if it's called for.
For shot evaluation, shot preparers will record dose/shot volume, any unusual flow characteristics, any necessary adjustments we make to either dose or grind, etc. I want to be as thorough as possible with our notes here and publish them.
Tasters will get their own scoring sheets, though I don't intend to have them score shots unless they choose to voluntarily: tasters will be asked to characterize and differentiate the shots and guess which one comes from which machine, based on the hypothesis that we're making or any other pattern they observe in the shot pairs. The hope is that the tasters will be able to guess correctly at the end. We'll serve water and/or carbonated water as a palate cleanser/refresher for tasters to use in between samplings.
As for some other specifics, Jon and I are thinking that at this stage, the best mechanism for testing is to use the same grinder at the same grind setting for both machines, and dose them similarly (identically if possible). I anticipate that there will be a pattern where one has a smaller volume than the other (probably the profiled one will be a little shorter), and I am conflicted whether to compensate for this by updosing slightly or just by stirring the shots and equalizing them by drawing some off of the larger one (I'm hesitant to add water to the smaller one, as one thing I anticipate is that tasters will notice reduced body in profiled shots, and adding water will skew that significantly). Any suggestions how to deal with that would be appreciated, but I am pretty convinced at the least that using the exact same grind for each setup is key to doing an absolutely direct comparison of profiling.
For what it's worth, the profile I mentioned ('vaguely lever-like') will be starting the pump at about "50%" for preinfusion, raising the pressure as soon as the gauge stabilizes (and you can hear the chamber fill), but smoothly, to 8.5 bars, holding it for about 7 seconds, and then gradually dropping the pressure to 7 bars till the end of the shot.
My hypothesis for this profile is that tasters will consistently observe the shot (compared to the flat profile) is shifted away from bitter, either to sweeter, brighter, or both. I anticipate that the tradeoff will be reduced shot body. I am curious if tasters notice a consistent reduction or increase in shot complexity/nuance, and also curious of their overall impression (if profiling, assuming it's consistently different, improves the shot for them and why).
Again, your thoughts are welcome; thanks for reading... let me know if I missed any key details.
Split from 'Pressure Profiling' With The Fluid-O-Tech TMFR Pump by moderator...