For the student of coffee, there are mysteries that tantalize one's reason and senses. I recently wrote about one: we lack a simple method to describe how fine we are grinding our coffee.Here's another mystery: the stirring thing. It is often mentioned how full immersion brewing methods -- like french press, vac pot, Aeropress, and the Brewer Formerly Known as 'Clover' -- are extremely sensitive to the way the grounds/water mixture is stirred. A small change in technique seems to have a big effect on the end result. Along these lines, Alistair has been very particular in the way he stirs his Clover brews, and Jaime's the same with his vac pots.
So...do we have to practice stirring plain water for months (as James Freeman reportedly did) before we're "worthy" to buy a $20,000 Japanese syphon brewer? And is it necessary to carve a bamboo stirrer by hand, or will a stainless steel wisk get the job done?
To take this line of questioning a little further, could a robotic stirring mechanism do better (eg, be more accurate, more consistent) than a trained human? Or is there an irreplaceable component of motor control and feedback that the flesh-and-blood Alistair, James and Jaime are utilizing? Zander once told me about the original Clover concept; it included automated grinding and stirring mechanisms, but those complex functions were deemed unnecessary for the specialty market. Hmm...that will change, given the goals of CEC's new owner.
Like the grind fineness problem, I imagine the stirring phenomenon will slowly give up its secrets. Twenty years from now we'll know a lot more about it than we do now. But it will take many careful observations by many hyper-observant baristas before this comes to pass.
Is stirring just about how much of the available surface area is exposed, and for how long? I can't imagine there is much more than that - I wonder what different techniques do in terms of extraction %. It should be reasonably easy to test (reasonably....) in a stable brewing environment.
ReplyDelete(I am full anticipating my "reasonbly" to be destroyed.)
Hi James:
ReplyDeleteThanks for taking pity on me and posting a comment!
> Is stirring just about how much of the available surface area
> is exposed, and for how long? I can't imagine there is much more
> than that
What you propose above was pretty much my first reaction to the stirring "debate." And if that is all there is to it, the best approach would be something like "grind a little coarser and do an extremely thorough stir."
But people who I respect seem to think there's more to it than that. I'd like to remain open-minded about this.
At the very least, I believe it's generally accepted that the "cake" of grounds that's left in a vacpot's upper bowl performs some self-filtering. And to the extent that one's stirring style alters the geometry of that cake, it will alter the result.
Your extraction test sounds like a very good first step.
I'm close to calling non-intended shennanigans on this whole zen stirring thing with vacpots that barismo and the NYT articles help to propogate.
ReplyDeleteI've been using these things now for about 11 years, and I'm constantly open to trying new ways to use them.. . over the years, my vac pot technique has changed and evolved. Here's some things that I think do work:
a) controlling the heat source during the kick-up / during the steep time. I've found that dialing down the heat once all the water has gone north helps make a better cup
b) stirring during the kick up helps just evenly coat the grinds, aiding initial full saturation
c) no special stirring technique required - just be gentle, don't worry about the whoosh, the pattern, the "amount of stirs".
d) the most important thing in vac pot coffee after having good coffee, good water, fresh grind, good grinder, is the filter, and its cleanliness. I give my cloth filters (metal underneath) a good bath in an Oxy-clean / hot water solution after every use, including some scrubbing. I've tried just doing soap cleans, and had problems (soap contamination on the shot destroying bloom, no matter how well I thought I rinsed the filter); water cleaning followed by storage in a glass of water in the fridge, a la oldschool 1950s technique, etc). Even try putting the entire thing in the dishwasher after use. None work as well, or help contribute to a better cup, than the oxy-clean method.
If there's things to be anal about with vacpots (and there's a few), IMO, there's more important things than a practiced stir technique. I've seen vids of Japanese vac pot masters and I cringe when I see how long the ground coffee sits out exposed to air as they get their game on.
Hi Mark:
ReplyDeleteGood tip about the Oxy-clean.
I also like your take on the stirring thing -- one would HOPE that given the right grind, there oughta be a reasonably wide range of stirring times/intensities that will give good results. Maybe I've paid too much attention to tales of the weird and wonderful.
Guess it's time for another hit from the Neti pot. :-)
Mark,
ReplyDeleteYou are a collector of lots of coffee stuffs including vacs. If I collect a dozen tea pots, it doesn't make me an expert nor does that alone discredit anyone else's experience no matter how long I have been doing it. I can easily pull the creds of the published author and respected roaster who trained me, but so what? That means nothing because it's all relevant. And to lump us in with that stupid article and your beloved halogen lamps or anything to do with Blue Bottle's method is grossly ignorant of the approaches.
People should test all the approaches and remember there is no right or wrong and absolutely no fucking zen in brewing a vac pot.
Andy,
test all possible answers.
Jaime, dude!
ReplyDeleteWhy so harsh? I seem to remember reading the unmistakable "IMO" within Mark's thread.
> Andy, test all possible answers
ReplyDeleteJaime, the whole post was about (despite my natural skepticism) trying to be open to the possibility that subtle changes in technique could be important. Not sure exactly what you mean by testing all possible answers, but I'm trying to keep an open mind.
Someday I'd like to visit you guys and, if you're into it, I'd like to see how you do things.
Is the cake of grounds in the vacpot just filtering as the water moves down, or is there significant turbulence (down at the scale of the individual grind particle) as the water moves down through the cake?
ReplyDeleteMike, I don't think there's much turbulence at all, at least on a gross level. The water is very smoothly drawn back down to the lower kettle.
ReplyDeleteJaime, I'm not going to get into a "who's dick is bigger" contest with you - I don't have to.
ReplyDeleteInstead, for Andy et all, I'm going to throw another curve ball out there, without giving my own conclusions on the matter.... if you really wanna study how the vac pot works, you have to study it in all its forms... or at least, all that you can reasonably get.
I'm talking balance brewers. The dynamics of flow are similar with the sole exception of the full vacuum effect on the cake vis a vis the vertical siphon system (the balance brewer does a partial vacuum and leaves some liquid behind, not much). The steep times (as long as you keep the right side kettle) are similar. The full immersion brewing are similar.
But in all my years using balance brewers, including side by side with vacpots, and TRYING to mimic brewing conditions as close as I can, there's always been, 100% of the time, a difference in cup taste. Not much most times, but it's there.
I have some theories on why this is; but haven't looked into it for years now. But I think looking into this more may actually help with real improvements on siphon coffee brewing methods (instead of these fanciful, stir techniques for show).
Japanese teach by showing, not by telling... and after yearly visits to Japan, and numerous syphon coffees...
ReplyDeleteIt is my strong belief that the syphon stirring "techniques" are simply timing mechanisms.
stirring "techniques" are used as a mnemonic so that you can consistently, from muscle memory, repeat a specific time for a given coffee. After a few months brewing syphon at the caffe, I've found that most coffees fall within a pretty close range. Of course, there's always room for tweaking!
Regarding Vac Pot brewing: If anything, most people grind too coarse, but that's for another discussion.
Happy brewing!
John -- that's a great insight and makes a lot of sense. Thank you.
ReplyDelete> stirring "techniques" are used as a mnemonic so that you can
ReplyDelete> consistently, from muscle memory, repeat a specific time for
> a given coffee.
John, that's a fascinating theory re: vac pots. I'm in no position to confirm or dispute this, although I can't imagine that Jaime's gonna go along with that one! :-)
But certainly in terms of the Clover brewer, such a mnemonic would be unnecessary....
we lack a simple method to describe how fine we are grinding our coffee
ReplyDeleteSince grinding does not produce grains of a single size, the best you could do would be a profile of the proportions of grains of different sizes.
In a former career, I used to do soil analysis using a stack of sieves of a range of sizes with the largest opening size on top and the smallest on the bottom just above a tray. The soil was added to the top sieve and the stack of sieves was placed on a vibrating table (if you were lucky) or just shaken energetically. The sieve analysis test would result in a list of the weights of soil held back by each sieve.
There is a description of the test here.
Of course you would need one of these and one of these
> stack of sieves
ReplyDeleteAccording to Illy, the stack of sieves doesn't work well for finely ground coffee (as in an espresso grind). The oily fine grounds stick together and give very inaccurate results.
"The oily fine grounds stick together and give very inaccurate results."
ReplyDeleteIn which case you need one of these!
It is worth registering so that you can read Controlling Coffee Quality using Laser
Diffraction.
> In which case you need one of these!
ReplyDeleteAgreed: the point of my "Humble wish for the year 20XX" post was that our industry could really use an inexpensive Laser Particle Size Diffractometer.
> It is worth registering so that you can read "Controlling
> Coffee Quality using Laser Diffraction."
Registered, yes, it's an interesting article. Curiously, when I increase the rpms on my Robur the grind gets coarser. They found the opposite on their grinder.
I love this article.
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