What are the causes of donut extractions and how can it be remedied?

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Shirikatsu
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Joined: 8 years ago

#1: Post by Shirikatsu »

I've recently received my new espresso machine, the Bezzera Unica for those wondering and I'm trying to properly dial it in but I sometimes get donut extractions. I've read the typical threads here so don't fret but it's because of that that I am confused. I've seen some people say that a non uniform distribution causes donut extractions and others say that it could be overdosing.

So what is the real root cause of donut extractions and what should be done to remedy this?

Bill33525
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#2: Post by Bill33525 »

I have found overdosing to be the main culprit of doughnut shots. Some roasts [darker especially] take more real estate in the basket than others. So while you may be in spec on weight the puck can be too high in the basket. Try reducing the dose till the shot starts wetting in the center of the basket rather than the outer circumference of the basket. Hope this helps.

TruBrew
Posts: 25
Joined: 9 years ago

#3: Post by TruBrew »

I've been having inconsistent extractions for months. At first it was due to a lot of sloppy technique. I wasn't being meticulous about keeping my shot weight consistent, and I was having difficulty getting a level lamp. that caused me to play with my grind settings a lot, further confusing things.

I've been getting more consistent across the board, but I still haven't been getting even extractions. Even on my best looking extractions, I had some noticeable doughnutting. I am using a ridgeless VST18 and realized that even though I had started dosing exactly 18g every time, if I insert the basket into the grouphead and then remove it again (dry) it would leave a screw mark on the center. I have to down dose to 16g to not see a screw mark on a dry puck.

My pucks are now quite wet after extraction and don't knock out uniformly, but I'm looking for better coffee, not better pucks.

I still have plenty of room for improvement, but things are betting better.

whitedime
Posts: 104
Joined: 8 years ago

#4: Post by whitedime »

I am wondering how you get a level top of the puck if you don't intitially fill the basket and "strike off" the top excess. I have ordered a plastic card meant to fit inside my porta-filter, but how do you go about creating a flat ness without filling the basket first?

brianl
Posts: 1390
Joined: 10 years ago

#5: Post by brianl replying to whitedime »

tapping the side of the portafilter with your hand. Then tap down on a surface afterwards. gets me close enough to get good results using a VST basket.

The most important thing is just locking in and then removing the portafilter to see If there is an impression on the puck. overdosing causes a lot of issues IMO.

nile24
Posts: 58
Joined: 9 years ago

#6: Post by nile24 »

Are certain machines more susceptible to doughnut extraction? I have an 88 cremina and all my shots start from the outside despite changing grind and dose.

h3yn0w
Posts: 476
Joined: 13 years ago

#7: Post by h3yn0w »

Nutating tamp helps with this issue.

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Travisimo
Posts: 68
Joined: 11 years ago

#8: Post by Travisimo »

If your grind, dosing & tamping are consistent.

** I find that I get better results with my lowering my dose in a ridgeless VST 18 using less such as:
17g to 17.5g

Then you get a puck that will knock out and say in one piece usually without major issues of extraction.

I use 2 second preinfusion and use my variable speed router dial to slow my Gaggia vibe pump down. Less then 9bar is more forgiving.

As always, make sure it is with good quality fresh coffee that is a medium to medium-dark if espresso.
Light roasts are more picky and don't grind or extract on modest espresso machines. Sorry don't have a Slayer or GS3...I wish!

brianl
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#9: Post by brianl »

Travisimo wrote: As always, make sure it is with good quality fresh coffee that is a medium to medium-dark if espresso.
Light roasts are more picky and don't grind or extract on modest espresso machines. Sorry don't have a Slayer or GS3...I wish!
I don't agree. I wouldn't be saying any 'golden rules' when it comes to machines. I used to have a Pid Gaggia Classic and it did light roasts just fine. No more likely to donut than any other roast.

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Travisimo
Posts: 68
Joined: 11 years ago

#10: Post by Travisimo »

It is all up to personal taste yet medium to medium - dark grind better, finer and extractor easier I find than lighter roasts.

I have done plenty on my Gaggia yet the main point I was mentioning is:
Tamping aside, {Dosing} fill it too much or not enough... you usually get odd channeling and poor extractions with machines.

If you have light roasts the beans don't seem to grind and extract as "fool-proof" without tweaks. I use a variable speed router control that slows or increasing vibe pump pressure. If I didn't the light roasts would not turn out as good as they would otherwise.

Sorry for the brief message. Not meant to pass "golden rules" only results from tried and true empirical deduction.

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