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LR Dark roast extraction PI issue

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3 weeks 4 days ago - 3 weeks 4 days ago #16913 by Patrick Aldis
LR Dark roast extraction PI issue was created by Patrick Aldis
Hi everyone,

I’ve had my LR for a couple of weeks now and have been getting great shots on medium and lighter roast beans, usually hitting 32g in 30secs from 18g in basket.

I’ve just started on a bag of Monmouth Organic Espresso (Blend) that is a bit darker in roast and am having real trouble dialling it in. My current process is:

PI set to 1.0
18g in basket
Target 32-34g in cup
Londinium distribution tool and a funnel to distribute
Gentle tap and then St Anthony BT wedge to level out basket
lightish tamp with either St Anthony New Levy or Londinium tamper

I’m getting even extraction, no channeling etc.

My issue is that If I set the grind setting (HG1) to hit 32g in roughly 30seconds like I usually do, the time to first drip during PI is way over 20 seconds and the espresso extremely bitter.

I’ve made the grind setting a fair bit courser in the hope of speeding up the PI time, it’s brought it down to around 10-12, but the shot rushes through in around 15secs. These faster shots are slightly less bitter but still not amazing.

Anyone have any tips on what else I could tweak to reduce bitterness and get the best out of these beans? If I up the PI pressure to 1.2 that does speed up the PI time to first drip a bit, but again still bitter. I read a light tamp is supposed to help darker beans but it doesn’t seem to have made a huge difference for me.

Any help gratefully received,

Thanks

Patrick
Last edit: 3 weeks 4 days ago by Patrick Aldis.

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3 weeks 4 days ago #16914 by Frans Goddijn
Replied by Frans Goddijn on topic LR Dark roast extraction PI issue
Hi Patrick,

This sounds as if you got a much darker roast than usual. How fresh is the roast -- do you know the roaster?

How is the smell from the grinds?

With darker beans I keep PI low, like 1.2 and I slowly lift the lever after 5-7 seconds. The lever 'catches' rather high which is fine, and the initial pressure helps to complete pre-infusion and start the flow.

You do not state exactly what brand and type basket you use to fill 18g. Maybe try 15-16g.

Best,

Frans

L1-P, L-R, Compak R120 & E8, Pavonis, Rocket, Mazzer, Fracino Roastilino & PXG4, Coffee-Tech FZ-94, Tonino, VSTlab IV, Acaia scales, Pencil tampers

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3 weeks 4 days ago - 3 weeks 4 days ago #16915 by Patrick Aldis
Replied by Patrick Aldis on topic LR Dark roast extraction PI issue
Hi frans,

Thanks for this. The beans are these ones:

www.monmouthcoffee.co.uk/product/organic-espresso/

It’s says they are a mix of “ coffees from Suke Quto (Ethiopia), La Bolinda (Bolivia) and El Pastoral (Nicaragua).”

They smell fine and only purchased last week and I believe Monmouth have a fast turnover of coffee so would not think they would have been sat around too long their end. The was no roasting date on the bag however.

I was thinking I should always wait until the first drips are seen before lifting the lever, I will try your way of lifting after 5-7 seconds irrespective of if it’s started dripping or not and see how that works, il let you know how I get on tomorrow - too much coffee for one day today :)

Edit:. forgot to say, it’s the londinium 18-20g IMS basket I’m using.
Last edit: 3 weeks 4 days ago by Patrick Aldis.

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3 weeks 4 days ago #16916 by Reiss Gunson
Replied by Reiss Gunson on topic LR Dark roast extraction PI issue
if you want to run dark/ish roasts i strongly suggest you add the restrictor to the thermosiphon; londiniumespresso.com/store/parts?product_id=70

this will allow you to run a higher pre-infusion setting with no mucking around

reiss.

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3 weeks 3 days ago #16921 by Nico Vierl
Replied by Nico Vierl on topic LR Dark roast extraction PI issue
Where do you see the difference in using the restrictor vs lowering the boiler temperature? Or is the goal to have a higher water temp for a short while with greater cooling from the group during the extraction?

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3 weeks 3 days ago #16923 by Reiss Gunson
Replied by Reiss Gunson on topic LR Dark roast extraction PI issue
raising or lowering the boiler pressure is a very ineffective tool for moving the brew temperature (a significant change in boiler pressure hardly moves the needle on brew temperature - as anyone with a dipper will know)

for this reason we keep the boiler pressure constant in the range 0.8-1.0 bar and adjust the pressure in the pre-infusion circuit by small increments to achieve significant movements in brew profile

but if users are only interested in dark roasts you can run out of room to drop the brew temperature low enough, even at low pre-infusion pressures, and it becomes a bit of a stupid fiddle (much beloved on places like home barista with their silly 'hold your face a certain way' routines and i can get my machine to do anything)

instead you place a restrictor in the thermosiphon and this reduces the rate of flow in the thermosiphon and you can run much higher preinfusion pressures on dark roasts, say 2 bar, and it all works very nicely

kind regards

reiss.

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3 weeks 15 hours ago - 3 weeks 15 hours ago #16943 by Patrick Aldis
Replied by Patrick Aldis on topic LR Dark roast extraction PI issue
Hmm, I wasn’t aware of that part. I assume if I fitted it, I’d have permanently lower group temps which would be less than ideal on medium to light roasts.

To be honest, using frans tip of just cutting PI after 5 seconds helped a small amount, but I was still getting bitter brews. The dark roast is now finished, so I think I’m just going to stick with medium / light roasts more now as I think I prefer them.

Thanks for everyone’s help though :)
Last edit: 3 weeks 15 hours ago by Patrick Aldis.

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2 weeks 4 days ago #16949 by Carl Jones
Replied by Carl Jones on topic LR Dark roast extraction PI issue
Hmmm, didn't know about the restrictor as an option for the LR, either, not that I'm only interested in dark roasts. Recently ordered and received the Wifi dongle (working fine) and maintenance kit but might have also ordered the restrictor ( londiniumespresso.com/store/parts?product_id=70 ) if, as you thought, it would not effect the ability to brew lighter roasts as well.

I searched but might still have missed it, was there a follow-up (in the description above from 30Jan2020) about testing the 'impact at both ends of the temperature spectrum'?

Thanks,

Carl

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2 weeks 4 days ago #16950 by Reiss Gunson
Replied by Reiss Gunson on topic LR Dark roast extraction PI issue
hi carl

yes, adding a restrictor pulls the brew temperature down, quite a lot, across the range

a machine with a restrictor in will be fine with medium roasts but it won't get hot enough for nordic/ultra light roasts

kind regards

reiss.

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