How to Make Decent Paper-Filtered Espresso

Beginner and pro baristas share tips and tricks for making espresso.
User avatar

#1: Post by »

Motivated by several high LDL results, reading that Cafestol is a possible LDL launcher in some people, and a deep-rooted need for tinkering, I gave this idea a go just to see how my espresso experience would change.

We already have one coffee+Cholesterol thread here, and I REALLY wish this thread will ONLY cover the espresso part, not the health part. Please help make my wish come true.

So, this thread is about: 1. how to make decent paper-filtered espresso? and 2. whether it reduces Cafestol/Kahweol or not? While still wondering about the second question, I started with the answer for the first question. Now to the process & photos:

First I took a new Aeropress filter and cut it to cover the perforated area of a Synesso double basket:

Then ground some 15g on my Versalab right on top of the filter:

Next is a photo of the last third of the pour. I line-pressure-pre-infused for about 5s then jumped to 8+bar. Handling the phone(camera) overwhelmed me and I didn't catch much of the first part of the pour. I don't know if it channeled in the beginning or not:

The shot started all-crema and slowly stabilized, just like regular shots. The crema was much denser than on regular shots, probably because the paper filter bursts any bubbles:

The basket bottom/holes were unusually clean, understandably so:

The paper filter was quite saturated before cleaning...

..and remained so even after washing with warm water, see contrast to a cleaner one:

Crema persisted even after after all the cleaning, photographing, etc, maybe 5 minutes after the pour:

The taste was shocking, it didn't taste "filtered" as I anticipated, but like it was slightly underextracted! The temp/grind was right on but it could be that the shot channeled, or that the filter absorbed most of the bitters and the shot leaned too much to the sours.

I'm not sure what to make of that. but more importantly, I have no idea and no way of knowing if this reduces Cafestol/Kahweol or not.

Washing and reusing the filters doesn't look like a good option given how discolored they are after cleaning. Cutting a fresh filter for every shot with scissors is a pain. I haven't decided where to go from here yet, but at least this filtering business doesn't produce undrinkable espresso.

Hope you enjoyed this enough to give it a shot and share your experience.

EDIT: just a little update, more paper-filtered shots confirm the channeling possibility on that first one. All subsequent shots were much more balanced...makes me suspicious if there is anything filtered?
"Beans before machines" ;-)

User avatar

#2: Post by aecletec »

Cool experiment. I look forward to hearing from your further experimentation.
I wonder what differences, if any, you'd have with pre-wetting the filter.
(Maybe it'd stick to the basket better and reduce the chances of the espresso bypassing the filter? Less absorbed espresso?)

User avatar (original poster)

#3: Post by (original poster) replying to aecletec »

I thought that won't work because it would be like using a wet basket.
"Beans before machines" ;-)


#4: Post by Marc »

Interesting experiment, fines are a part of espresso and the filter probably catch a lot of them and thus underextracting the final coffee. Well, that's my guess.

User avatar (original poster)

#5: Post by (original poster) »

I added a note about shot balance to the end of my OP. To reduce chances of it being messed, here it is quoted: wrote:just a little update, more paper-filtered shots confirm the channeling possibility on that first one. All subsequent shots were much more balanced...makes me suspicious if there is anything filtered?
"Beans before machines" ;-)

User avatar
Supporter ♡

#6: Post by yakster »

I think the concern with an improperly dried basket is the possibility of side channeling if there is any moisture on the sides. If it were possible to rinse the paper filter and put it in the basket and dry the sides, I don't think there'd be a problem.

Over on CoffeeGeek, Alan Adler posted about a study by The Department of Agrotechnology and Food Science, Wageningen University in the Netherlands here that you might want to review. I'm almost tempted to try this myself, but until I have high LDL results I think I'll pass.

Maybe you could find a punch to make trimming the Aeropress filters to the right diameter easier... then sell cut filters on the side. Since the latest trend seems to be metal pour-over filters (Kones, Disks, Coffee Catchers) this might be an interesting twist.

LMWDP # 272

User avatar

#7: Post by peacecup »

I press an uncut and unbleached filter paper partly into the basket with the tamper. This leaves a perfect impression of the basket OD size. I cut around this size about 2mm and press it into the basket. Works best if the basket is wet, so it sticks to the bottom. Then I press the edges around the basket to seal it before dosing. This all takes an extra minute per shot, but I'm not usually in a hurry. I'm not sure if it makes a big negative effect on the espresso quality - I haven't noticed any.

LMWDP #049
Hand-ground, hand-pulled: "hands down.."


#8: Post by Aaron »

About trimming the filter down to size, I was wondering if you could use a cookie cutter adjusted to the correct size. Maybe a cookie cutter could be molded to your circular size. It might not be sharp enough, but if it works that would be nice.

Very nice experiment and interesting results. Now to test the filtered versus non-filtered results to see if it had any effect...
“The powers of a man's mind are proportionate to the quantity of coffee he drinks” - James McKintosh

User avatar

#9: Post by nixter »

I'm no scientist but I suspect the filter isn't filtering the cafestol given the pressures involved. In a normal drip brew process the paper filters the oils because simple gravity is not sufficient for the oil to pass through the paper. In the pressurized environment of the brew head I suspect that the oils will pass right through. Even if it doesn't then it will find the path of least resistance which is underneath.

I could of course be totally wrong!!


User avatar
Team HB

#10: Post by cannonfodder »

Why in heavens name would you paper filter an espresso basket?
Dave Stephens