Taste impact of fines - Page 2

Coffee preparation techniques besides espresso like pourover.
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AssafL

#11: Post by AssafL »

aecletec wrote:The stickiness and distribution of fines in grinder research has been called agglomeration; for this reason I think the stirring/whisking process works well for brewing. I've found straight WDT to not be as useful as whisking then shaking side-to-side to level.
Agglomerate is the correct term indeed. The problem is that the term also includes fines agglomerated into a clump. There is little reason for those to extract.

Navigate refers to specific type of agglomerates that consist of a boulder that has a puff powder coating of fines. (I called them puffs - doublehelix - fractals). The first I encountered this concept was in the Brita Folmer book.

I always assumed WDT was a catch all phrase that described a process of getting fractal-like uniformity in a puck. Shaken or stirred or whisked. I may be wrong on that, but it matters little. If your grinder stratifies or segregates fines - you'll need a WDT style tool to homogenize it.

A last point on the subject - another hypothesis I raised for the differences incorporating or removing fines is effective dose.

If fines overextract while boulders underextract, removing fines would suggest that the dose actually increased (albeit the weight decreased, the leftover mass underextracts!). Hence instead of adding more boulder to compensate - one would need to remove boulder to keep EBF.

This dichotomy between dose and extraction would suggest that there is an effective dose - that is the coffee that is available to extraction. Obviously playing with fines reflects heavily on the coffee available for extraction.
Scraping away (slowly) at the tyranny of biases and dogma.

malling

#12: Post by malling »

She is not just reffering to boulders as such, but also the taget sized particles, all particle agglomorates, and just like navigate, I think we need to differentiate between different type of agglomeration

I also started to whisk/stirr grind prior to brewing filtee coffee, if this indeed help with the fines agglomeration. Then that can explain why I noticed an improvement in extraction and taste.

But I belive your right about Brita Folmer.

I think Navigated plans to put whiskes/stird grind under a microscope, and I also surggested to investigate coffee that had just been bloomed as weel as grinds after the entire brewing process.

Navigate

#13: Post by Navigate »

yakster wrote:Thanks for posting this, it's very interesting. I find when grinding with my Lido 2 that you'll often find a lot of fines that stick to the bottom of the grinder. These separated fines are probably best not used and just knocked off the grinder after removing the catch cup.
I got a Lido 3 and see the same: a lot of separated fines stick to the bottom of the grinder. All along I have been careful not to get them into the catch cup ... but rinse the off over the kitchen sink, so the grinder is clean for the next time.
yakster wrote:I'm not sure that it's the speed of the grinder that results in the separated fines but maybe it's the the metal in the bulk grinder chute and the metal in the bottom of the Lido 2 that caused the fines to stick to the grinder.
I see your point - since fines stays back on the not-very-speedy-Lido.

But I guess there are two meachanismens in this:
1) fines left on the grinder in stead of in the catch cup
2) the distribution in the catch cup.

When you look closely at the milkpitcher photo I posted - look at the grind pile it self. On top of the grind pile the particles are smaller. While closer to the buttom the particles are larger. Thats a typical distribution of particles of different sizes when stirred/shaken/moved.

Navigate

#14: Post by Navigate »

Cute to call it "fractal grinds". I hadn't thought of that one .... But isn't fractals a repeated pattern several times ? Here it looks like only one time; smaller particles on larger. Its not like the middle-size-particles also stick onto boulders and covers them like fines do.

Navigate

#15: Post by Navigate »

malling wrote: I also started to whisk/stirr grind prior to brewing filtee coffee, if this indeed help with the fines agglomeration. Then that can explain why I noticed an improvement in extraction and taste.
I have also started doing this: remove what is easy to remove - and the stir to persuade the last of the separated fines to stick on the bigger particles.


Navigate

#16: Post by Navigate »

AssafL wrote:I called them puffs
Also cute with puffs. My nickname is the Danish word for "Teddy bear" ... when the surface of larger particles is covered with fines.

Navigate

#17: Post by Navigate »

Talking about boulders:
Along with the microscopy photos of the different grinds in my starting-post I also had a fraction of particles larger than 1100 um. It just doesn't contribute to this subject about how fines are placed differently therefor I did not include it at first. The post was just so long so I toke it out.

Note: like with the fines - there is no common size definition on when a coffee particle is a "boulder". I guess the term more has to do with the role in the brewing than the actual size. So don't put emphasis in the 1100 um here. It is just the largest sifter-size I got.



But it's interesting to see in comparison with the 400-1100 um fraction af the grind (photo 3 in my starting post). Here again:



You can see the size difference ... and then it seems that a bit more fines is left on the boulders. This is after several minutes of shaking in the Kruve sifter. Maybe because the smaller medium-size particle rub more on each other ? The larger boulders might bumb each other off quicker.


By the way - thanks to Steffen Lav for lending me the microscope.

Navigate

#18: Post by Navigate »

I also did microscopy on grind after brewing to compare sifted grind i.e. particles without fines attached - versus normal grind with fines attached.

But it wasn't as clear as with the dry grind (not this far anyway, maybe it can be done better). Because with the water the particles swell up and kind of integrate with the fines.

Here a photo of a normal grind after a V60 extraction. You can kind of make out how small particles are attached to bigger ones. But they don't stand out as clear as in the dry grind.



This is from the same V60 brew:


And here a sifted grind - the 400 to 1100 um fraction:

Navigate

#19: Post by Navigate »

What I found the most interesting of the wet grinds so far is; to see what the separated fines looks like.

They look like totally dissolved into a gel. No longer a dark cellulose core.

This makes me speculate: could it be the "dark cellulose part" that holds back the unwanted over-extracted taste ? So it's only when we got this fines-to-fines alone that we get the bad over-extracted taste ? Just speculation.

This microscopy is of the "mud layer" on top of a V60 brew. Some times the surface of the drained coffee grind in the filter has a thin layer of fines on top (I would guess it stems from "separate fines")



Here the "mud layer" on a drained V60 brew. I lifted some of the surface out to show how the grind underneath is coarser. I will pay attention if this mud layer can be avoided by stiring the grind before throwing it into the filter (to reduce the separate fines in the grind).


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AssafL

#20: Post by AssafL »

I wonder if the Gel is leftover polysaccharide hydrocolloids.

Same polysaccharides probably give Espresso the thick unctuous body.

Thank you for sharing. Very exciting thread.
Scraping away (slowly) at the tyranny of biases and dogma.