Can "puck turbulence" be avoided when under-dosing?

[Elbasso]

I came across the below image in another topic: http://www.home-barista.com/forums/pulsating-flow-on-andreja-premium-t6838.html

I have had the same results when experimenting with 13 grams or other small doses. No amount of tamping or NESW tricks could prevent this. As I see it, the coffee will always tumble around in the PF if there's too much headspace. Is this correct?

[CafSuperCharged]

I do not think I underdose at 14.4 grams.
After the shot, usually the surface is fine, the puck pretty dry and consistent and comes out into the knockbox in one piece. With a hollow surface, the edge of the puck just touches the spring-rim of the basket.
In the other thread I commented on this photo in that context, but now I have an additional hypothesis: do you "post-infuse" or "post-profile" with the E/61?
I always do that.
Most of the movies in this site show an abrupt cut off.
In my case, with the lever in the middle position, the pressure, without the pump on, will decrease and when I push the lever further down, the rear outlet does not really make that explosive noise letting the pressure go (and sucking grind through the shower screen?)

Before I get reprimanded about taste, I have read quotes from Italian barista stating they could taste the difference between having done this or not - I may be able to do so, but never tried and certainly not in double or triple blind conditions.

Still, it would be interesting to see the heuristics associated with this turbulance phenomenon, indeed.

Regards
Peter
Netherlands
Europe

[another_jim]

I get soggy pucks at low doses. Unless you are in a barista competition and are getting scored on pretty and dry ones, don't worry about it. The sogginess that makes for a messy puck is also what heals any cracks, and what makes low dose shots nearly channel proof.

[AndyS]

As I see it, the coffee will always tumble around in the PF if there's too much headspace. Is this correct?

I don't think you can look at a photo like that and assume it represents what was going on in the portafilter during the extraction. When the three-way valve is released at the end of a shot, all hell breaks loose as pressure is released in the opposite direction.

[AndyS]

I get soggy pucks at low doses. Unless you are in a barista competition and are getting scored on pretty and dry ones, don't worry about it.

I with you, Jim. I've gotten used to the soggy low dose pucks.

But are you kidding? In competition, one is really judged on the texture of one's pucks?

Why?

[HB]

Barry Jarrett would know the minutia, but last time I went through the SCAA workshop on barista competitions, the instructors (Brent Fortune, Marcus Boni) make it clear the criteria was consistency. They also talked about respecting regional differences regarding dosing, but at the time they were more concerned about extreme updosing than downdosing. They specifically don't want to see a slushy puck one time and a firm puck the next. Where this designation fits on the score sheets, I'm not certain... it may be lumped under the nebulous "Understands Grinder" score.

[AndyS]

...the nebulous "Understands Grinder" score.

The grinder is not hard to understand. It takes the big beany things and makes them into little beany bits.

[Elbasso]

do you "post-infuse" or "post-profile" with the E/61?

Ergh....?! You lost me there. Are these two terms for the same thing or are they different techniques?

[cannonfodder]

One thing you want to keep in mind, you have a 3 way valve. At the end of the shot that 130ish psi portafilter gets a rapid pressure dump. That will suck air/water/coffee out of the portafilter causing the ugly puck. Machines without a 3 way will do the same when the slightly pressurized portafilter is removed. Since you are 'normal dosing' there is headspace in the portafilter so there is some turbulence in there when the portafilter gets the rapid decompression treatment. In an overdosed basket the puck has swelled and makes contact with the shower screen and get compressed against it. That tight fit will hold everything together.

Don't worry about it, as long as your puck does not have holes in it (channeling), it is not an issue. It does make a little more mess on your grouphead so you may want to clean water backflush after every brewing session along with a grouphead wipe with a towel to remove the stray grounds. Don't worry about puckology, spend your concentration/time working on cupology. You will get a better return on investment.

[malachi]

I don't think you can look at a photo like that and assume it represents what was going on in the portafilter during the extraction. When the three-way valve is released at the end of a shot, all hell breaks loose as pressure is released in the opposite direction.

As the infamous "perspex portafilter" video showed, there really isn't true turbulence in the portafilter while brewing under normal circumstances - and there is the potential for incredible "movement" once the pressure is released.

[barry]

I with you, Jim. I've gotten used to the soggy low dose pucks.

But are you kidding? In competition, one is really judged on the texture of one's pucks?

Why?

A low dose puck will have a larger amount of free water on top at the end of the shot. Not all of this water is siphoned off and/or blasted out by the pressure release at end-of-shot, resulting in a puddle of water on the puck. It's almost the same phenomena as one sees on machines not equipped with a 3-way valve: water above the coffee has no where to go.

In competition, the key is consistency in dosing. We check the puck for relative consistency of density & structure. If one puck in a set is mushy, the other should be mushy, too. I don't consider a mushy puck to be an inherently bad thing, except when it is clear the extraction was pushed too far or proceeds too quickly.

[dsc]

Hi,

As the infamous "perspex portafilter" video showed, there really isn't true turbulence in the portafilter while brewing under normal circumstances - and there is the potential for incredible "movement" once the pressure is released.

Is it possible to see the video somewhere? I'm very curious how the inside of the PF looks during the extraction.

Cheers,
dsc.