Comments on: Gold Cup / Pyrite Grinder

By: Fines, Up-dosing and Under-extraction « Field Notes on Coffee

Fines, Up-dosing and Under-extraction « Field Notes on Coffee — Tue, 18 Oct 2011 22:44:03 +0000

[...] 3. http://www.devicestyle.co.jp/en/products/brunopasso/ca6/index.html 4. [...]

By: FTGFOP

FTGFOP — Mon, 24 May 2010 12:18:01 +0000

You sieve your grinds too! I thought I was alone!

It feels so wasteful though that it kind of embarrasses me, especially when the beans are good.

Recently I had the thought that cold-brewing the fines would be putting them to good use. Summer’s coming after all.

I might also be able to use the liqour to spike my hot chocolate with caffeine. Hmm…

By: J David Waldman

J David Waldman — Fri, 12 Feb 2010 02:18:44 +0000

so, getting a bit conceptual, why not design a graduated (in size) filter topology, or just some type of grid/topography that somehow is responsive to the migration pattern of fines during the extraction process, thereby segregating the smaller particles – your choice to in- or ex-clude them. alternatively, why not pass off the mechanical grinder problem to an active membrane (filtration) problem – i know it’s a bit conceptual, but this is what membrane scientists do with very complex organic compounds. one of our customers (we call him doctor membrane) does just this in the petroleum field. create a selective membrane, disposable, inexpensive filter, that removes the organoleptics that we deem unfavorable in the end result. i have spent some time discussing this with dr membrance, and, with some expert guidance (extensive knowledge of organic chemistry as regards coffee taste, e.g. dr illy & co), he believes it is doable. sorry, for the diversion – this eliminates the grinder chase which will likely never be capable of removing all fines, unless we come up with a “fines trap” in the exit path.

By: MARCO ÜBER PROJECT » UBER GRINDER RESEARCH

MARCO ÜBER PROJECT » UBER GRINDER RESEARCH — Fri, 12 Feb 2010 01:04:39 +0000

[...] Best illustrated (in a not very laboratory but perfecty understandable way)in this great post by DavidWalsh – go to the thread and read David’s coments [...]

By: Colin Harmon

Colin Harmon — Mon, 29 Jun 2009 18:07:25 +0000

My understanding of the extract mojo was rammed home this week by Messrs Stack and Kaminsky in Cologne and I am hugely excited about the potential advancements that can be made in specialty coffee using this and similar technologies.
Perhaps the most exciting thing is that by laying down markers in Coffee Brewing (i.e. extraction, dose, water ratios, time) we can begin to ask questions in areas we never had the luxury of asking before.
The ability to describe your coffee in definitive numbers is undoubtedly geeky but an exciting advancement for an industry that has such a strong internet-based community. We now have the ability to define our coffee brewing and communicate findings as opinion based on fact rather than a fact based on an opinion.

By: David

David — Mon, 29 Jun 2009 10:50:09 +0000

@Nick

Fines play a very different role, depending on the extraction environment.

“Very different” I dunno – somewhat different I accept. It seems logical to say that any brew method that gets a certain percentage extraction out of relatively coarse grinds, will get a higher level of extraction from relatively fine grinds. Whether fines experience a different microenvironment to “normal” grinds under conditions of turbulence seems plausible, though perhaps would only exacerbate the problem. Really entering the world of speculation here so I’ll stop.

@Paul

The Gold Cup is a drive to bring up the standard of filter everywhere. We do not discern, but Speciality coffee is the logical home for Gold Cup brewing.

Yes, sorry. I should have beem more careful on that point.

By: James Hoffmann

James Hoffmann — Mon, 29 Jun 2009 09:15:51 +0000

My brain is slowly coming around to your point about extraction speed – sorry about this.

By: Paul Stack

Paul Stack — Mon, 29 Jun 2009 08:59:01 +0000

David,

Firstly, I congratulate you on a great article. I have been both captivated by the discussions and delighted to see Gold Cup and brewed coffee being discuused logically.

The Gold Cup is a drive to bring up the standard of filter everywhere. We do not discern, but Speciality coffee is the logical home for Gold Cup brewing. They will envitably find each other through the medium of that section of the coffee community which cares.

I have used the extract Mojo on the Uber Boiler at the weekend in Cologne and while I know the pallet is subjective, a 60-65g/L brew i.e. not dosed higher but extracted between 19-20% was sparkling and balanced. It helped that we used great coffee of course courtesy of Square Mile. These were brewed on Chemex with a Tanzania – as close to single peak grinding I can find). Therefore minimal fines.

I’m all about the science and while my gut tells me a uniform grind with as few fines as possible will deliver the best filter, supporting your argument David, I will aim to scientifically chart the differences in the short term.

Thanks for attending our Gold Cup course and congratulations again on a great article.

By: Nick Cho

Nick Cho — Sun, 28 Jun 2009 23:53:15 +0000

Good discussion. This is something that I’ve been spending a lot of time working on, experimenting, and thinking about. I really want the ExtractMojo as a result.

@David: I’d been thinking about trying to sieve-out fines for a few years, but never got around to it. I’m glad to hear your results have been good. The only thing I have to add is that keep in mind that the rate of extraction of any of the particles, including the fines, will vary significantly on the brew method, particularly regarding agitation. Fines play a very different role, depending on the extraction environment.

@James: I’ve been thinking a lot about updosing for brewed coffee, and I’m frankly troubled by it, but for reasons that I’m not myself entirely clear on. I’ve been witnessing doses of 20-60% higher than “standard” lately, and with greater frequency, and it always makes me frown.

What bugs me the most, I suppose, is that it’s not really necessary. I’ve been making outstanding Chemex brews with about 40g for about 0.6L of water, with all of the characteristics we look for. When dosing goes up to overcome the brew method (usually to shorten the brew time), it feels like cheating to me. An inelegant solution to an otherwise classic problem.

The elegant solution: refine your technique or practice your technique. “Refining,” more often than not, seems to be to extend the brew time to a more “proper” duration.

This is merely based on my current experiments and rumination… so it’s a work in progress for sure.

By: David

David — Sun, 28 Jun 2009 23:31:04 +0000

What is speed but the percentage extraction as a function of time?

Let’s assume that my sieving was 100% efficient. It isn’t, but the point is still valid.

In the sieved brew I have 1 population that is x % extracted.

(A) 1*X = 17%

(17% is the real number).

In the unsieved brew I have 2 populations, the normal grind that is X % extracted and the fines that are Y % extracted.

(B) 0.95*X + 0.05Y = 17.5%

(17.5% is the real number)

From (A) we know X = 17%.

Therefore (B) becomes

0.95*17% + 0.05Y = 17.5%

16.15% + 0.05Y = 17.5%

0.05Y = 1.35%

Y = 27%

ie the fines are 27% extracted.

The speed is therefore 27% / 4 minutes = 6.75% per minute etc.

The speed of the “normal” population is 17% / 4 minutes = 4.25% per minute.

Of course the speed will vary over the course of the brew.