thoughts on a controlled study of brew times

Last month a new controlled study of brew times in French press coffee was released.  Conducted by Daniel Drazenovich, Chief Technical Engineer for the micro roastery Old Wwworld Cafe, the process and findings were quite interesting and worth a read. (See, "Perfectly Timed French Press Coffee".)


The Coffee Catcher's Nate Jones had the following thoughts on the study:

"It certainly makes intuitive sense that the surface area of grounds exposed to water coupled with the total volume of grounds should affect the timing of coffee brewed.  Personally, I think the 200 degree pour is a bit on the low side, but I have no reason to supposed that that would comprehensively skew the results.

"This reminds me of an all day experiment I've been wanting to do involving brewing French press coffee by visual cues. I do it, and John [Custer] does it, but I haven't had a chance to figure out exactly what I'm reacting to in terms of sight, smell or perception of time that tells me when to press.  I think the color of the crust on the top of the coffee does change as the brew continues, perhaps as oil extractionslows, but I can't quite verbalize those cues yet. Anyway, this chemistry-heavy approach reminded me that sometime soon I'd like to do a controlled direct-perception series of brews and evaluate the results."

Brew Colloids and Fine French Press Flavor: Part 2 of 2

Brew Colloids and Fine French Press Flavor: Part 2 of 2

by Nate Jones
(Read Part 1 of 2)

Last week's tech-a-thon was all about how brew colloids, tiny masses of fine coffee and oils, trap flavor solids. The post concluded with the suggestion that the Coffee Catcher may allow active colloid management for the first time. First off, this article should be taken as an invitation to explore further - not the definitive truth on the Coffee Catcher's role in French press brewing. After six months of daily brewing, I've developed enough ideas to lay out some questions I'd like to discuss further, and this seems like a good time to invite the coffee community to weigh in.

One of the most consistent test results we've had with the Coffee Catcher has been apparent direct filtration of a significant % of brew colloids, with colloids separated from the brewing area and the cup by the stainless Coffee Catcher disc in the carafe. Coffees have tasted cleaner and flavor profiles have held up longer. At first, my assumption was that the key variables in this filtration process were the size of the mesh and the strength of the pressure wave generated by depressing the plunger in the French press. However, Sam Lewontin (@coffeeandbikes) pointed out that Scott Rao has argued that cleaner flavor comes not from a finer filter that traps more colloids but from the physical arrangement of the brewing system itself that either naturally separates heavier colloids or does not. 

Thinking in terms of brewing systems rather than mesh size, I now suspect that most of the filtration occurs in the first few seconds of the brew, as water is being poured over the bed of coffee on top of the Coffee Catcher. The turbulence and downward pressure generated by hot, falling water generates an initial mixture of coffee and water, and I think that that heavier colloids may naturally separate so that colloids are pushed beneath the disc by water pressure and turbulence during these first few seconds. Colloids would then be kept from brewing with the coffee from the start of the brew. In that situation, the cake of grounds atop the disc would effectively plug the press and keep filtered colloids from entering the cup when the press is emptied.

So here's the question: I've been able to achieve "full" filtration using the Coffee Catcher disc with a regular pour of hot water. I've also achieved apparent zero filtration multiple times by deliberately pouring very gently and slowly directly over the Coffee Catcher. So if no filtration and "full" filtration are possible, would it be possible to vary the pour pressure to achieve different levels of filtration? Think Hario pour overs, but for French press.

Another potential brewing system tweak introduced by the Coffee Catcher is a more effective French pull, a technique referenced in a thread over at Home-Barista.com. During a marathon brew session a few weeks ago, Alex Negranza (@Barista_Alex) and I experimented with bottom filtration of the press - pulling the Coffee Catcher immediately after the brew cycle was complete.* To our palates, the results were distinctive and intriguing, including a softer mouth feel and a seemingly rounder flavor profile with more fruit. In system terms, pulling the Coffee Catcher seems to filter very fine coffee solids in the foam and the brew, but doesn't seem to remove brew colloids filtered beneath the disc.

So here's the question: does the Coffee Catcher indeed produce a French pull with a distinct flavor profile relatively easily? If so, how and why is this making a difference relative to traditional French press techniques?

Finally, Alex has written an interesting post over here about siphon filtration using a modded Coffee Catcher. The common theme with the French pull above is vacuum, or bottom filtration of some sort. I'm all questions on this one. What exactly makes bottom filtration distinctive? Is it only that filtering from the bottom keeps fines at the top of the brew from coming through, as Rao has suggested? Is a relatively mild vacuum beneficial in flavor extraction terms? Can bottom filtration be tweaked (either by modifying pressure or mesh size) to extract a more desirable flavor profile? 

So, that's where I'm at. The Coffee Catcher will soon be in the public domain, and I hope sharper minds than mine will tackle some of these Q's - brewing up delicious coffee along the way!

* Please Note: this involves getting fingers close to hot coffee, and you could be burned. Try at your own risk! In practice, it seems the surface of the coffee cools extremely rapidly, and I've yet to burn myself touching the surface of the coffee during a pull - even immediately after brewing. Nevertheless, you should use your own judgment and proceed with caution as you try this.

The Adventures of The Coffee Catcher!

In a recent fieldtrip, Nate Jones visited Mark Barany of Kuma Coffee, where he had the opportunity to observe the coffee bagging and delivery process (...a lot of fun from what we hear!)  Afterward, they had some time to brew a few French presses, which gave the Coffee Catcher a chance to shine.  In Nate's words

"...wow.  Fantastic Guatemala Il Injerto, huge body, streaks of blueberries, maybe a hint of cinnamon? Sweet and syrupy. [Mark] tastes this coffee all the time, and he thought it was one of the best presses he'd ever had of it."

The great flavor caught Mark's attention, and it looks like we'll have at least one Kuma Coffee present at the French press competition on June 18th.  We're looking forward to seeing how Seattle's various coffee experts use the French press.
_____

...On a side note, Nate's homecoming after meeting with Mark was less-than-ideal.  Apparently, that morning while rushing to deliver coffee to his wife, Charity, Nate accidentally left the Coffee Catcher sitting in the compost container with the grounds.  Later that day Charity dumped the whole compost - including Coffee Catcher - down the 5 story garbage shoot.

Upon arriving home, new Kuma coffee in-hand, Nate hurried to brew some of the outstanding roast for Charity...only to discover they were short one Coffee Catcher!  It was bad.

Needless to say, within 5 minutes both of them here were downstairs making a valiant trash-diving effort, searching for the missing item (...we'll save you the more gruesome details).  Finally, the Coffee Catcher was found.  Back upstairs and thankful to be reunited, the disassembled Coffee Catcher was soaked in Visions' phosphate-free coffee cleaner and boiling water for 15 minutes before running it through a cold rinse.

The heroic rescue efforts were rewarded with a fantastic brew of Rwanda Abakundakawa.  Apparently, the Coffee Catcher's thorough cleaning removed all silt buildup and emphasized the the spice and fruit notes in the Rwanda admirably!

While recounting the tale Nate added, "We're thinking of calling the coffee catcher "The Precious", after Gollum."

Brew Colloids and Fine French Press Flavor : Part 1 of 2

Brew Colloids and Fine French Press Flavor : Part 1 of 2

by Nate Jones

(What a title!)

First off, hat tip to Sam Lewontin of Why Not? Coffee for the conversation that started this and to Scott Rao, who helped me understand the relationship between colloids and coffee body/flavor in Everything but Espresso and The Professional Barista's Handbook (TPBH).  (Head to home-barista.com for a handy quick reference quote from TPBH on brew elements. )

Jumping in, the non-water part of coffee is a mixture of dissolvable coffee solids and gases (the stuff that gives flavor and aroma, respectively) and non-dissolvable solids. These (relatively) large non-dissolvables form colloids as they spread evenly through water during brewing, bonding with tiny oil droplets and trapping dissolvable solids before they can dissolve. Another way to put it: suspended masses of particles, oil and dissolvable solids are known as brew colloids.

Brew colloids affect coffee in two key ways. First, these relatively large masses of coffee stuff contribute to the coffee's perceived weight in our mouths (body) and to mouth feel (a looser definition that encompasses body, but also texture, consistency and anything else your mouth feels apart from taste). More colloids in coffee = greater body, and of course traditionally brewed French press coffee is loaded with colloids and renowned for its heavy body. The down-side of all this body is a muddy, blurred flavor profile. In traditionally-brewed French press coffee, there are so many brew colloids that a significant percentage of available dissolved solids are mopped up before they can dissolve and lend their specially tasty chemicals to the brew. So instead of tasting the full orchestra of flavors, the tongue tastes available flavors plus colloids, which are perceived as both/either heavy body and syrupy mouth feel and/or a muddy, or silty mouth feel that screens flavor.

No surprise, one key to good French press coffee is balancing the number of colloids formed in the brew for an optimal body - taste experience. Previously, the only way to influence the number of colloids in the brew was to prevent them getting into the carafe in the first place - in other words, to employ a high quality grinder that produces grinds of a consistent size with a low percentage of relatively tiny colloid-forming coffee solids. I think there is now a second way to manage the body - taste balance: the Coffee Catcher.* I've conducted daily (tasty) brewing experiments for six months, and I think the Coffee Catcher can consistently remove colloid-forming solids from the grind mixture at the start of the pour, before many oily, flavor-trapping colloid masses can form. The result is a lighter-bodied French press brew, with significantly improved flavor clarity and extended coffee life-time. It may be that the latter occurs because there are fewer colloids in the cup, and therefore undesirable flavor extraction at cooler temps is minimized (solids that dissolve at cooler temps tend to release undesirable, bitter flavors into the cup).

But what's really tantalizing is the potential to actively manage colloid presence within the carafe for the first time. More testing is needed, but it's possible that certain brew conditions can be deliberately tweaked to influence the colloid transparency of the Coffee Catcher mesh - thus potentially allowing French press users to actively tweak the number of colloids in the brew, tailoring the body-taste balance to a particular coffee or brew parameter. I'll lay out my thoughts on this more fully in Part 2, due out next week...

*Legal Stuff: The Coffee Catcher is a patent pending product of Kaffeologie (TM), all rights reserved.

Pour speed and silt behavior with the French press

As you can tell by our previous post (“Finessing the brew method”), we’ve been giving French press technique quite a bit of thought lately.  Nate Jones recently made this interesting observation during his French press experimentation:

“I saw something very, very interesting when I used the Coffee Catcher today.  I think that the filter effect of the Coffee Catcher is governed by the rate-of-pour during the first few seconds of the pour as the water meets the grounds.  If, while pouring the coffee maker lets 'er rip, then the water penetrates the mesh of the Coffee Catcher and forms a single reservoir with the liquid above the mesh, leaving silt able to pass through the Coffee Catcher’s mesh base.  However, if the water is poured gently, the water and grounds act together to seal the mesh, causing an air bubble underneath - and no silt.

“If this is repeatable, it is a definite win since it would give the traditionalists an option to still clean up with the Coffee Catcher.  Also, it reveals the breadth of flavor one can achieve using the Coffee Catcher.  Finally, and most interesting, it may mean a new dimension to the French press experience - something experienced brewers can use to precisely guide silt filtering."

The Coffee Catcher vs. The Old Fashioned Way

Here's a little video of Nate and John demonstrating the Coffee Catcher way vs. the Old Fashioned Way of cleaning the carafe with a spoon.  We sure had a lot of coffee fun while shooting the footage.

no one is safe...

Our founder John Custer is currently wishing he was in Seattle where the Coffee Catcher samples are being produced and distributed.  While Seattle-based founder Nate Jones is enjoying the Coffee Catcher on a daily basis, John is still struggling with cleaning his French Press the old fashioned way.  At least he only has to endure until the Coffee Catcher ships in April.  But in the meantime, check out John's latest cry of agony, received in the Seattle office via email this weekend:

"DADFREAKINBLASTIT!!!  I BROKE MY FRENCH PRESS THIS MORNING, AND I JUST BROUGHT BACK A LOAD OF BEANS FROM INDONESIA!   I CAN'T WAIT TILL OUR PRESS COMES OUT TO REPLACE IT.    GRRR.....:-("

 Hang in there, John!  Help is on the way.