Andy wrote:Is it really gel? Or do the wet fines just appear gel-like under magnification?

A fair question. Lots to explore !

One thing pointing in the direction that it is a gel is this photo from my eaylier post (#18).

It is a photo of a normal grind after a V60 extraction. To inspect it under the microscope I have placed the grind on a plate and then spread it out ... Here I have made red circle around where it looks like gel-behaviour between larger paticles ... just like a gel being streched ... small grind particle do not have that shape.

These findings also gave me a new perspective on the bloom phase in filter/drip brewing - the first 30 seconds with a little water.

Bloom phase is said to serve the purpose of degassing. Makes good sense. Tiny air bubbles on the surface of the grind will block extraction with water.

Additional, I have always been thinking of it like when a drop of water lays on paper: it takes a while to absorb into the celluloses. And not before it has swollen up the deep extraction can get going.

With this finding in mind ... where fines result in different taste depending on if they are separate or connected to larger particles ... I would think that the bloom phase also is where the fines integrate with the larger particles ... and form some kind of a gellyfish unit (?) that works great in extraction ... in contrary to fines only connected to other fines that over-extract.

Maybe the point in letting it sit for 30 seconds, not disturbing it ... is to let this integration form ... because if agitated some of the fines will go off ?

Just a thought.

Matt Pergers procedure to stir the sludge with a spoon right after the first water is added ... isn't it suppose to be finished within the first 10 seconds ? and then leave it for 20 seconds before adding more water.

What happens if you don't let it rest - but go right to poor water ? will you get more of this "naked thin taste" as with sifted grind ?

Basis for a lot more experimentation

I prefer a slow, center-drip pour over. It keeps the gas bubbles on top and allows plenty of bloom time. I'm not sure how it affects fines, but I do not get a muddy gel on top.

If indeed it does create a gel it does explain why agglomerates of fines don't extract ruining the designed EBF.

Anyone versed in the use of hydrocolloids (dispersion and hydration) and gel forming proteins knows that dispersion of fine powder in liquid is hard. The outer particles form a gel barrier that prevents the inside from hydrating. It becomes a yucky clump that ruins texture, Furthermore, since the clump will not hydrate, the ratio of gel agent to flavor base will be off. So a runny gel with clumps.

Hmm.... Overextracted ristretto is similar to an understabilized, clumpy ice cream base.

One way to tell if you have gel is to poke a toothpick in the mass the try to "tug" on it. If it doesn't flow like water then you have some type of concentrated colloidal suspension, which is likely and maybe a gel. Gels are more rigid...think Jello.
Very neat thread!

Almico wrote:I prefer a slow, center-drip pour over. It keeps the gas bubbles on top and allows plenty of bloom time. I'm not sure how it affects fines, but I do not get a muddy gel on top.

you're underextracting... look at all the dry grounds on the sides, up to 2:00 when you cover them with the rest of sludge, but that still doesn't mean the get extracted properly...

You would think, but it's just not the case. The coffee at the edges at 2:00 looks dry, but I assure you, they are well-saturated. At 1:40, when the paper starts wicking, the grounds at the edge are saturated. If I pour slowly enough, coffee does not start dripping until the 1:00+ mark.

I dose 19g to produce 250ml of finished coffee and it does not taste under extracted in the least. I've been doing it 100s of times a weekend for 2 years. Try it.

Almico wrote:I prefer a slow, center-drip pour over. It keeps the gas bubbles on top and allows plenty of bloom time. I'm not sure how it affects fines, but I do not get a muddy gel on top.

At the end there is a lighter layer on top .... would you say that is foam ? somewhat like crema on a espresso ? and not a layer of fines ?

Note: I never called the mud layer on top of the drain grind a "gel". Do not look gel-like. That is only under a microscope.

Yeah, the "thing" in the center of the red circle here is more of a viscous fluid than a solid gel.

Yes, more investigation is needed. Just hard to look at it under actual brew-conditions with a microscope.

Navigate wrote:At the end there is a lighter layer on top .... would you say that is foam ? somewhat like crema on a espresso ? and not a layer of fines ?

Note: I never called the mud layer on top of the drain grind a "gel". Do not look gel-like. That is only under a microscope.

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It is foam, but not crema. I think it is just carbon dioxide bubbles. Pouring slowly allows them to gently rise the surface. But it seems to make a better cup not actively incorporating them back into the grounds bed.

I do get a mud layer pouring the same way into my Chemex with grinds from my R120. Can't figure out why.