Wednesday, September 29, 2010

The French Press Shake

Agitation in French press extraction seems to be largely unexplored. We tried some serious agitation in the press this week, and enjoyed some very tasty results with our Koke. In addition to significantly increased extraction, the coffee tasted noticeably cleaner than even via the traditional Coffee Catcher method.

For the record, here's the process we used:

1. If you tend to use a finer French press grind, coarsen it up a few notches. On our Virtuosos, we found 27/26 led to over-extraction, and 31 was about right.

2. Use a half dose in an 8 or 12 cup press, in order to leave room for aggressive agitation.

3. Throw in a Coffee Catcher, pour and let brew stand for 3 minutes.

4. At 3:00, begin shaking the press vigorously in a consistent, circular motion. You should see a substantial whirlpool effect.

5. Shake continuously until about 3:45, and press at 4:00. Pour out right away.

So, would 4 minutes of continuous agitation inevitably over-extract? What about agitating during the first minute, instead of the final minute? There's room for more experiments here...


  1. Update: I tried shaking continuously from 1:00 to 3:45 this morning. Even using the Virtuoso's coarsest grind setting, I could taste some over-extraction. The continuous shaking also cooled the brew much more than the original shake technique.

    The original shake technique offers a superior combination of heat retention and optimal extraction.

  2. This subject intrigues me. I have not found any serious study of this, on line. (By serious, I mean controlled testing.) There's an anecdotal tradition that you pour water on the grounds, and then perhaps stir once, or not, and then never again until you plunge. Why?

    The assumption is that stirring (or agitating of any description) encourages over extraction, which I take to mean an unacceptable bitter flavor.

    I'm not sure I know what "over extraction" tastes like, though. Coffee always has a bitter component, in counterpoint with, or in contrast to (and not necessarily in balance with) the sweetness.

    I'm skeptical that anything too finicky about the method can really be repeated reliably or tasted. We are not--most of us are not--performing tightly controlled chemistry, in laboratories. Some of us do control what we can--weighing the ingredients, using a thermometer to check water temperature, and running a timer--but the results are nonetheless fairly variable, I'm sure.

    I'm no engineer, and have a rudimentary understanding of both experimental protocols and statistical error, but I'm quite sure there's more variance in the tasting than in the method. Or put another way, I assume that the controls I have outlined are specific enough to fall comfortably within the ranges of individual, and general (comparing person-to-person), tasting ability, but any others fall outside. I would be very happy to have this view tested--and proven wrong. Really!

    I try to think of coffee making as first of all a very pleasant ritual. Science comes second. But I also enjoy tinkering and changing my mind about things. I'm also a cook, and enjoy the imprecision and the craft, and honing that craft, and learning to cook more reliably--I've come full circle.

    For what's it's worth, if it amuses you to know, my current agitation technique follows: I preheat my thermal-walled 24oz glass carafe with boiling water, then add boiling water by weight (which cools to about 200F), then add the weighed coffee grounds (i.e. on top of the water) and stir immediately vigorously with a chopstick to dissolve as much as I can. I let it rest, lid on, then after 2 minutes I stir likewise again. After 4 minutes I plunge and pour.

    I use a fine grind, almost espresso fine, but that second 2 minute "rest" the plunger descends fairly easily (in 10s). And the resulting brew is very nice indeed!

    So if it's nice, why bother trawling the internet in search of agitation research? I don't know--an agitated mind? Restless? Curious? Vaguely irritated that it seems to be one important part of the coffee preparation that is foggy with anecdote? It amuses me. Ah. Good enough reason!

    I'm enjoying the blog. Good luck to you. Enjoy your next cup.


  3. @ Patrick

    Glad you like the blog. Your comments are trenchant, particularly in light of my apparent failure to establish statistical significance for the test described in French Press Fines.

    Statistical significance is a slippery fish. It says something very precise about a clear hypothesis. It's a useful tool, and I think it's an appropriate tool for challenging and testing coffee best practices, but I'm realizing the home kitchen may not have the tools necessary to conduct that research.

    Right now, I'm stumbling over composing a sufficiently accurate hypothesis that could be tested and produce not only statistically significant results, but meaningful results.

    I'm in discovery mode. What the heck is going on in my coffee? Suspended solids is too vague for me, but it's the best I can do for now.

  4. Update: Scott, roaster at Herkimer Coffee in Seattle, tells me he has been brewing with a variant of the French press shake for years. He starts his shake at 2.5 minutes and allows a 30 second settling period. Not sure on this point, but I think the brew time is a bit shorter than 4.