Taste impact of fines - Page 6

Coffee preparation techniques besides espresso like pourover.
Navigate (original poster)
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#51: Post by Navigate (original poster) »

Andy wrote:At high magnification, water will appear viscous because of the surface tension, will it not?
Good point.

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AssafL
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#52: Post by AssafL »

malling wrote:It make perfectly sense that we don't extract every single bit in the larger particles. We only want to extract up till a certain limit, beyond that point we start extracting undesirable notes/flavours from the coffee, like the undesirable flavours we do get from smaller particles, these tend to have a very undesirable ill tasting bitternes, sometimes dry and ash like.
Well - yes and no. Obviously we would want to stop extraction before the harsh stuff comes in.

But if some parts of the puck are extracted to "straw yellow" color while others keep hold of the "yummy sweet brown" then we are simultaneously over and under extracting (overextracting from the yellow, under extracting from the unreachable brown).

So what if the real difference between grinders is not the EY - but the percentage of leftover "brown" after extraction? (in this sense, the Mazzer would leave more brown spots than, say, a Mythos or an EK43).

BTW - According to Wikipedia (and many children's songs), brown is a composite color of Yellow and Red and Black (or blue) to make it dark. We love to quote here that espresso crema should be as much mahogany/brown/red color as possible - and least possible yellow. By that reasoning taking out the red would leave the Yellow in the spent puck.

Maybe a Tonino like device can be used to measure the color of coffee after extraction. I wonder if a Robur and Mythos would measure differently on the Yellow - Brown scale. If a VST can tell us the economic yield of an extraction, maybe color can give us the flavonoid yield.
yakster wrote:Chaff would show up as different colors.


Good catch. Maybe the Yellow is chaff...
Scraping away (slowly) at the tyranny of biases and dogma.

Navigate (original poster)
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#53: Post by Navigate (original poster) »

AssafL wrote:The color is reminiscent of sucrose: It doesn't look like a scatter of pure Demerara sugar (varying depth of yellow color) - it looks like a mix of Demerara and Moscavado sugars. Moscavado being brown instead of yellow due to brown impurities (aka molasses).
Sucrose is colorless in itself (like table sugar). And this is coffee particles after extraction so easy soluble components are gone. Sucrose is very soluble and quite quickly in hot water.

I hesitate to single out what components gives the brown and yellow color. Coffee is highly complex. But isn't the brown color in coffee said to come from the Maillard reactions ... and caramelisation ... But aren't those very soluble molecules ... after all the coffee in the cup is pretty dark brown.

The question is what is left in the particles ... I thought about the cellulosis ... in itself it's colorless ... of cause might trap some of the less soluble Maillard products. But I stumbled across something else:

Lignin
It gives structural support in plants walls. Not that I know for sure that it is left in roasted coffee beans, but seems very likely. I stumble on in a google search. It plays a role in the color of paper.

From Wiki: "Lignin must be removed from the pulp before high-quality bleached paper can be manufactured."
And ... lignin is the reason that old newspapers turn yellow ! Newspapers dont need high quality paper and it's cheaper to make without removing the lignin.

But still, just speculation. Nothing is proved here.

From paper production:

Navigate (original poster)
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#54: Post by Navigate (original poster) »

malling wrote: It would be interesting to see a picture of very overextracted grinds to see if there is a difference.
We can take a look tomorrow. I anyway still havn't looked at the particles picked out at the end of the bloom phase. We can then compare that to the same grind after extraction.

This simple microscopy just has its limitations. One being - you can't look at the particles with out moving them around first: taking them out of the brewing vessel, placing them on a plate, spreading them out.

malling
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#55: Post by malling »

AssafL wrote:Well - yes and no. Obviously we would want to stop extraction before the harsh stuff comes in.

But if some parts of the puck are extracted to "straw yellow" color while others keep hold of the "yummy sweet brown" then we are simultaneously over and under extracting (overextracting from the yellow, under extracting from the unreachable brown).

So what if the real difference between grinders is not the EY - but the percentage of leftover "brown" after extraction? (in this sense, the Mazzer would leave more brown spots than, say, a Mythos or an EK43).

BTW - According to Wikipedia (and many children's songs), brown is a composite color of Yellow and Red and Black (or blue) to make it dark. We love to quote here that espresso crema should be as much mahogany/brown/red color as possible - and least possible yellow. By that reasoning taking out the red would leave the Yellow in the spent puck.

Maybe a Tonino like device can be used to measure the color of coffee after extraction. I wonder if a Robur and Mythos would measure differently on the Yellow - Brown scale. If a VST can tell us the economic yield of an extraction, maybe color can give us the flavonoid yield.



Good catch. Maybe the Yellow is chaff...
Who says that the last bit is yummy, perhaps the last brown bit that Seem to be Haarder to extract is mostly giving undesirable flavours to the coffee. It is simply not possible to not overextract, underextract and extract correctly at the same time.

My experiment with excluding the larger particles show me that we might actually want to have particles that underextract and particles that don't, a totalt uniform grind dosn't Seem to be that desirable aften all, I also had o conversation with another Pro barista and he agreed that a slightly lees unimodual grind seemed to be somehow desirable.

The EY is most likely an effect of the grind, it makes perfectly sense that there is more leftovers in less unimodual grind, as you would have allot more larger particles.


Navigate you might have a valid point about the Maillard reactions

Navigate (original poster)
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#56: Post by Navigate (original poster) »

But really I am more interested in how these particles behave and behave together ... than naming the chemical components.
I started my coffee exploration doing that ... due to my Food Science degree including lots of chemistry ... but didn't found that it helped much.

I am interested in practical experience - and then the scientific background knowledge can be very helpful for inspiration.

My point in the initial post was not so much what you see in the microscope photos ... but how the situation/placement of the small and large particles affect the taste. How fines only attached to fines taste over-extracted ... and larger particles without fines attached don't taste good either.

Navigate (original poster)
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#57: Post by Navigate (original poster) »

Which leads me to ... Earlier today I talked to Malling about what to study with the microscope tomorrow. We plan to look at grind taken out at the end of bloom and compare it with grind after extraction.

I mentioned this problem that the grind get "disturb" when you pick it up and spread it on a plate. I got the impression when the wet fines stick to the larger particles they are not strongly bonded - but only loosely attached. And therefor easily pushed/dislocated when touched. The best would be to have a microscope in the grind during brewing in the filter. It's just too dark to see anything even if you managed to do that.

Both Malling and me have observed how sensitive the brewing process is to agitation - at some points it is no problem .. but later it makes the brew over-extracted. Malling mentioned how not to overdo "the Rao spin" because it can result in over-extraction. I agree; its like you have to do it right after the water pouring. Later it will make trouble.

I then reflected on this ... can this be explained by the taste experiments from my post #1 ... that it taste good when fines cover the larger particles ... but bad when they are separated ... Hey, here is an idea:

During water poor in the brewing process the "fines-covering-the-larger-particles-agglomrate" (oh, I wish we had a shorter term for this) ... they float around in the water ... when you stop pooring water the turbulence of the sludge slows down ... and the grind settles on the bottom ... Maybe when the particles settle on top of each other and then get shaken (like by the Rao spin) ... then they will rub on each other and scrub off the loosely attached fines .. resulting in over-extraction !!

Shaking the sludge is no problem when the particles has not settled in - because they are floating in the water and don't really scrub on each other.

See my point ?

Navigate (original poster)
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#58: Post by Navigate (original poster) »

malling wrote:Who says that the last bit is yummy, perhaps the last brown bit that Seem to be Haarder to extract is mostly giving undesirable flavours to the coffee.
That is exactly what I am thinking: it seems to be a good idea that something is held back - the components that give the over-extracted taste.

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Almico
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#59: Post by Almico »

I sieved my R120 Chemex brew this morning with a #30 (600uM) just to see. I brewed the fines as well. I got 10g of "fines" to 45g of beans.

The sieved coffee (light-roasted Kenya) tasted very sweet, but lacked it normal body. The "fines" (at 600uM they are not exactly fines) tasted pretty good too, but there was a very distinct bite that was not present in the other batch.

I just bought a small, 3" SS #40 (425uM) sieve (w/cap and pan) to bring to my farmers markets and will use it for my customers to solicit their input. I need to do lots of testing with grind level vs sieve # to find the sweet spot where I get all the sweetness, as little bite as possible and still maintain mouthfeel and body.

Stay tuned...

Navigate (original poster)
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#60: Post by Navigate (original poster) »

Great with a field study with customers ;o)

Agree, 600 um is not that small.

Since you have a 425 um sieve ... then it doesn't sound like the Kruve sifter ? My set does not have that size, anyway.