The role of fines and what we really want from a grinder - Page 2

[The_Mighty_Bean (original poster)]

(If you're referring to the "regular lattice" as remaining a constant during the extraction process)


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No, I mean at the beginning. To produce the most even extraction possible.

[AndyS]

Don't forget, the fines move downwards. While they do tend (due to increased surface area) to wanna extract faster, you're also sort of tucking those fines down where they're more awash in already-brewed-espresso-extraction than water that wants to dissolve those precious solubles (a.k.a., percolation).

It's certainly a complicated scenario. What does your (true) observation above say about the results of the extraction?

[darrensandford]

This makes me want to brew a shot, then dry the puck, then slice it into layers, crumble it and then see how many fines are in each layer

[Matthew Brinski]

No, I mean at the beginning. To produce the most even extraction possible.

Ok, but fines tend to shift from their initial positions in the coffee cake once brew water is introduced. So, I don't think that it would make a significant difference if they were equally organized throughout the coffee cake matrix prior to brewing.


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[AndyS]

Now where is it we want those fines? The grinder spits them out sort of randomly,- wouldn't it make sort of intuitive sense that we want them as evenly dispersed throughout the basket contents as possible, creating a regular lattice with the coarser grinds?

One of the supposed advantages of dosered grinders vs doserless grinders is that the doser tends to keep things mixed up better -- especially when the barista does the rapid clonk-clonk-clonk-clonk with the doser handle as the shot is ground.

[barry]

This makes me want to brew a shot, then dry the puck, then slice it into layers, crumble it and then see how many fines are in each layer

Just don't use a machine which has a brew solenoid.

[barry]

Now where is it we want those fines? The grinder spits them out sort of randomly,- wouldn't it make sort of intuitive sense that we want them as evenly dispersed throughout the basket contents as possible, creating a regular lattice with the coarser grinds?

Wouldn't it make even more intuitive sense that the fines are NOT spit out randomly by the grinder, but in the "natural distribution" associated with grinding coffee?



I'm still trying to reconcile your quest for "even distribution" and your desire to shake a puck down to maximum density (which will congregate fines towards the bottom).

[The_Mighty_Bean (original poster)]

Wouldn't it make even more intuitive sense that the fines are NOT spit out randomly by the grinder, but in the "natural distribution" associated with grinding coffee?



I'm still trying to reconcile your quest for "even distribution" and your desire to shake a puck down to maximum density (which will congregate fines towards the bottom).

Sorry folks, I'm very slow in responding to these threads, with the bar exam under 2 weeks away. I'll respond to a number of comments once that form of medieval torture is over with.

Barry, just a quick answer- I'm not sure what "natural distribution" is, but I trust it to be desirable about as much as I trust "natural law". I think the way a grinder mixes the grounds during the grinding process is going to be unique to that make and model, and I'm not at all sure that grinder engineers have thought to optimize that blending process.

When I call it a blending process I am just referring to that "natural" mixing- not any sort of homogenization. It will differ depending on lots of variables including burr shape, burr size, length of path to the basket, presence of a doser, et cetera.

So, to answe your first question more directly, there may be so many variables involved that the lattice structure of the grounds -as spit out- will always be essentially random.


The question I have evolved into asking is, is there an ideal distribution and lattice structure of particle sizes, pre-tamp?

Do we want that sort of distribution homogenized so that, before the water hits, the particles start out close to an even lattice of larger and smalller particles? I am no longer at all certain that we want the fines to migrate towards the bottom before the water even arrives.

In other words, no need to reconcile the quest for even distribution with shaking the fines to the bottom. That's why I spun off this thread from the other one-- the question in this thread is where do we want those fines to go during the distribution process, and should we even care?

~tMb

[Jasonian]

I wish the new feature on Coffeed were available at the time, but this very topic was discussed at much detail about a year or so ago. (maybe less time, but that "feels" about right)

I tried searching but couldn't find it. If I do, I'll report back.



I feel the need to inject the notion that the coffee particles aren't randomly shaped. They are ribbon slices.

Such a shape offers a much higher surface area than otherwise thought. I don't think you can prevent the larger particles from extracting while the smaller particles extract.

I don't believe it is one or the other responsible for the bulk of the espresso's flavor. Surely, there are more than merely two grind sizes at work here. "fines" and "large" and everything in between are more likely to be found.

The question, is what is the "ideal" variance?

Do fines migrate? Sure! but how much?

Well, just the WDT is enough for me to notice a visual difference in extraction color, so I'd imagine a bit more than intuition suspects, but less than many seem to give credit to.


Just food for thought.

[fac10]

I recently ran across this article which may be of interest to those following this thread. The most interesting point being that some high-end industrial grinders are capable of generating 'bimodal' grinds, where the particle size distribution has two separate medians. Apparently this has some beneficial effects, at least with respect to the manufacture of espresso pods. Presumably, a cruder version of this effect could be achieved by mixing the output of grinders at two separate settings.

Perhaps the blended bimodal grind will be the next bleeding edge in the search for the perfect extraction.