Top 5 Grinders for Light Roast Espresso Application - Page 3

Grinders are one of the keys to exceptional espresso. Discuss them here.
guydebord

Postby guydebord » Feb 07, 2019, 11:00 am

Denis wrote:How you can say there is no difference in taste that human can feel, if you pull shots with the same coffee with a big conical (83 mm) you usually get 19-21 % EY and with a big flat suited for light roasts you can get 24-26% EY?


I don't think I have ever tasted coffee at 26% EY, thats crazy! Does it taste better than a standard reference of 20%EY?
In girum imus nocte et consumimur igni

Iowa_Boy

Postby Iowa_Boy » Feb 07, 2019, 11:11 am

Do you still see the EY difference with medium or darker roasts?
In other words, do flats result in higher EY with those roasts as well vs conical?

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Denis

Postby Denis » Feb 07, 2019, 11:52 am

Conical burrs deliver a different shape of particles compared to flat. They tend to drag and break the coffee and the flat break and cut more than break.

In grinder comparison and laser analysis diffraction the conical and some flat (this is geometry-rpm related) tend to do more boulders than other flat grinders.

Let's say we want to grind for espresso, and we know that for a traditional espresso we grind between 200 and 600 microns. In this range we are going to get the highest percent of grind particles. But some grinders deliver a high percent over 600 microns, up to 800/1000. Those are boulders. I am grinding finer than 200-600microns.

Now from a discussion and a presentation of Perger we know that water penetrates totally up to 100microns in the walls off coffee particle, watch this video and if you want to see the explanation about this watch after min 34 : http://www.youtube.com/watch?v=2lPGf1gM9nA ).

If we draw a circle with 100 micron radius we get a perfectly rounded particle with a 200microns diameter. That will be fully wet and extracted. For high extraction yields you need to grind fine and the distribution needs to be uniform, because if you have fines that will lead to choke, and if you have boulders that will lead to under extraction. Fines will lead to under extraction as well because water will be forced to find way out and do micro channeling.

There is another thing involved, the shape of the particles influence the hydraulics and how the water flows. A puck made out of square and angular bits will have more porosity and permeability than a puck made out of "flakes". The grind from flat looks similar to flakes. So the flaked coffee puck is harder to extract and in most cases people will say they have more channeling with a flat burr grinder than with a conical. Or I hear a lot my Kinu is way better than was my Lelit flat grinder.

To achieve higher taste or EY you need good coffee (air roasters like Loring will roast more even from inside out this means you can extract more from the volume of coffee, if the bean is undeveloped in the interior that will not allow you to extract) a flat grinder that has uniform grind and a flow/pressure profiling machine that does what you say (temperature, flow/pressure, time-stops-starts).

We humans like to over complicate things, we are curious and always search for more, it is never enough. Some may say what the hell! why would you buy almost "green" roasted coffee and try to make espresso out of it, remember this is a hobby. This is time consuming, a lot of money involved. Getting the last 5% out of anything is like this, I don't know if it was worth it.
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Bunkmil

Postby Bunkmil » Feb 07, 2019, 12:44 pm

Very interesting post Denis!

I don't have a refractometer but I am wondering if I could achieve high EY with my big conical/DE1 combo. The DE1 allows me to grind ultra fine without chocking my shots by controlling all the variables (temperature, flow/pressure, time-stops-starts). I have pulled amazing shots using a pause phase after the preinfusion. I have no idea what was the %EY though.

KarlosdelaMancha

Postby KarlosdelaMancha » Feb 07, 2019, 12:45 pm

I am a relative newbie to "high end" coffee but have been pulling shots at home for 20 years. I love this discussion of particle size and extraction yield as it provides a rational explanation of why bigger flats are able to do what they do. I certainly experienced the difference moving from a Mazzer Mini E to a Monolith Flat. Much more predictable shots, easier to manipulate shot times with grinder adjustments.

I think there are many parallels between hobbies. In the high end audio world there is also a mix of skepticism, faith and rational electrical engineering explanations for why cables, vacuum tubes, fuses, power conditioners do what they do. I'm noticing a lot of similarities between discussions on hi fi forums and HB.

Really enjoying all I'm learning on this forum.

-Karl
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Iowa_Boy

Postby Iowa_Boy » Feb 07, 2019, 1:07 pm

Denis, thank you for the great post! I have read this several times already to try to digest.
Is there a particle size definition for "fines"?
Also, I would love to learn more about extraction, grinders and particle size.
Are there any books or articles that anyone has come across that are particularly helpful?
I see that there is one from Scott Rao, Espresso Extraction: Measurement and Mastery. Anyone familiar with that?

nuketopia

Postby nuketopia » Feb 07, 2019, 2:00 pm

I still say it is a load of mythology.

Double blind test or go home.

My money is on no statistical evidence of taster being able to identify the burr type.

Same coffees, same dose and beverage output, same pressure and same brewing temperature, same water, ground to produce the same running time, served at same temperature.

Lots consisting of randomized samples to include lots consisting of all from one type.

Servers and tasters blinded to sample composition.

Betcha, no evidence of identifying the burr type. I'd even be willing to bet no evidence of being able to ID which are different.
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TomC
Team HB

Postby TomC » Feb 07, 2019, 2:18 pm

malling wrote:I did it several times and I never had any problems detecting each, the difference is quite noticable if you know what to look for!


Big claims require big evidence.

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Denis

Postby Denis » Feb 07, 2019, 2:55 pm

Same coffees, same dose and beverage output, same pressure and same brewing temperature, same water, ground to produce the same running time, served at same temperature.

Here is where you are doing the biggest mistakes everyone does when comparing grinders.

I'll give you a simple example, pull yourself or go to anyone else and do the following:
grind with conical - pull the longest shot you can up to 1:3 ratio. The Longest mean that you can drink it and it is ok as taste, no dark-bitter-slow flow shot. It will be between 35 and 45 seconds top (with preinfusion).
Grind the same coffee with flat (ek43s,flat max, eg-1) and pull the longest shot you can up to 1:3 ratio but stay where the taste is ok for you. It will be between 60 and 85 seconds top (with preinfusion).

Now ask yourself from where is that difference. Let me help you more, check this grind distribution made from someone here on HB (you can find other more precise and accurate laser analysis if you want to know more.

https://docs.google.com/spreadsheets/d/ ... =121288603

From my side of view, it the same if you believe me or not, just that flat grinders are hard to make to work for single dose for home barista, and people don't understand the difference. Flat=good, conical=bad doesn't exist, they are just different, taste and choose.


Here is what you get when you pass over the maximum that coffee/physics allows you to:

Image

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Chert

Postby Chert » Feb 07, 2019, 3:08 pm

Also off topic, but maybe an accompanying list of type 5 light roast coffees over which to argue about ideal grinder for, is needed.
possibly:
TW
Heart
Coffee Collective
Slate
Kuma

I don't know which blends or origin, I don't buy much roasted.

@Mivantsky or @cebseb or @malling suggest a list, preferably with specific origin or blend?