samuellaw178 wrote: I'm just quoting what the retailers are stating. One thing for sure is that in espresso/moka, the puck itself is also functioning as a porous filter. So that have reduced most of the grinds that would otherwise get in the cup or clog the filter basket holes.

Yes, puck obviously works as filter for the coffee inside it. As about holes, there is also very informative thread on this forum. 30 microns mentioned on that site is a tolerance of hole diameter, not the diameter

How filter baskets affect espresso taste and barista technique

vit wrote:Yes, puck obviously works as filter for the coffee inside it. As about holes, there is also very informative thread on this forum. 30 microns mentioned on that site is a tolerance of hole diameter, not the diameter

How filter baskets affect espresso taste and barista technique

Thanks Vit. You're right. Looking at my VST basket now, don't think it's possible for those holes to be 30 micron as they're obviously bigger than that. I guess I need to brush up my reading/skimming skills.

website wrote:They are manufactured with much lower tolerances, such that each and every hole is measured on every filter to ensure that they are all within a diameter limit of +/- 30 µm. That is, 30 microns

If one partially doses into a basket and lightly swirls it over a white plate it's easy to see how much fine materiel can come through the basket. Some percentage of the fines that are smaller than the holes in the basket end up in the cup. I'm sure they have considerable influence on the taste. I've always attributed tiger-striping to those particles, perhaps wrongly.

A better-aligned grinder ought to limit the upper end of the particle size distribution, i.e, nothing bigger than the largest gap between the burrs can pass through. Within a reasonable range of alignment, a perfectly-aligned grinder probably won't alter the variation on the lower end of the particle size distribution. The perfect-alignment folks also need to deal with those nasty thinly-sliced grinds that can be larger in two dimensions but still get through a narrow gap because they are thin.

Roasted coffee tends to be friable and only the largest particle size is determined by the grinder adjustment and maximum gap. The origin of the coffee and roast level has some impact on the degree of friability but it is very likely to be a near impossible variable to control easily. Burr design probably has the largest impact on the production of the fines.

Would an espresso or moka devoid of microfines taste better?

Using a well-cut Aeropress filter at the bottom of your basket changes the flow rate and in-the-cup results. Less (no) fines seem to migrate into your cup with the filter. Whether the taste is better or worse because of this, is for you to decide.

I was going back and forth for about a week from filtered to unfiltered making sure to create comparable drinks. The filtered cups had less body, but not profoundly less. The drink was nice and less bitter. I've since stopped filtering the puck. I didn't feel like the beverage was better, just different and if I can adjust my grind to re-balance my shot then I'd rather do that.

How did you determine the amount microfines that made it though given that some of are barely visible with a microscope? Standard coffee filter paper under pressure isn't an effective way to block <10um sized particles. I've been unable to clarify some coffee (e.g. moka) with 0.7um syringe filters.

There are several posts relating to sieving out all fines below a given size.

Spitz.me wrote:Using a well-cut Aeropress filter at the bottom of your basket changes the flow rate and in-the-cup results. Less (no) fines seem to migrate into your cup with the filter. Whether the taste is better or worse because of this, is for you to decide.

I was going back and forth for about a week from filtered to unfiltered making sure to create comparable drinks. The filtered cups had less body, but not profoundly less. The drink was nice and less bitter. I've since stopped filtering the puck. I didn't feel like the beverage was better, just different and if I can adjust my grind to re-balance my shot then I'd rather do that.

That is something I ought to try with espresso. I had experimented with an Aeropress once upon a time. Using double or even triple layers, I manage to get even cleaner/clearer coffee. I wonder what the effect would be if you use a triple-layer filter versus no filter on the espresso?

Given the finer nature of espresso grind, more layers might be needed to capture more of the fines.

In my hands adding filters sped up the extraction (espresso)--easy to imagine that adding additional filters would help trap more fines from winding up in your cup.