Impossible to pull a good espresso from light roast? Severe channeling problems

Beginner and pro baristas share tips and tricks for making espresso.
Maggiekw

#1: Post by Maggiekw »

Im new to this forum, but have learned alot by reading alot about others problem. Now i have my own problem that i hoped someone have a answer to.

I own a ecm synchronika and a ceado e37s that works great on medium/dark roast beans, but Im about to go crazy over the light roast. No matter what I do when pulling light roast shots it comes out bad..

No matter what i try:
18g dose/20g dose.
1-1.5 / 1-2 / 1-2.5 / 1-3 ratio
Adjust brew pressure from 10,5 down to 7bar
Grind finer or coarser
Adjust temprature from 92-96c
Flow control to get a pre infusion
Aiming for a time between 20-30 sec

The shots come out testing bad. Some are really terrible, some are drinkable with milk, but none are great. As a light roast it should have some extra sourness compared to medium/dark roast, but its missing the sweetness, when i try to adjust this it becomes bitter or even bitter and sour. When i increase the yield it takes the bitterness of, but the acidity is right back.

The thing that drives me crazy, and my conclution the problem is channeling. When I pull a dark og medium roast the shots look nice. Even extraction, nice colors, thick and creamy, but when i pull light roast there is severe channeling. I try my best, and I cant really see how there is channeling?

Here are the tool I use:
Wdt tool
Calebrated tamper
Distributor
Grind into a cup and shake before putting it in the vst basket.

Everything just to eliminete the chance of channeling, but still it is severe channeling, alot more then i deserve compared to my level of prep i think.

I will post some videos tomorrow but I hope some of you have a explanasion on whats going wrong and why every other video I see of pulling light roast dont have that problem, and why the shot at my local roaster tastes so much richer? There i can taste sourness and bitterness, but just the good notes. The coffee im using now and that I commited to get right is a kenyan light roast, freshly roasted.

Im not perfect in english, but I hope you understand what my problem is.

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CoffeeMac

#2: Post by CoffeeMac »

If too sour it seems to indicate under-extraction. Grind finer, higher brew ratio, increase brew temp. You might want to aim for a longer brew time, say 40-50 seconds. Explore up-dosing (19-20g?) to slow things down. You could also try the E&B superfine basket (see other thread).

Channeling, presuming your puck prep is on point with WDT, etc., can be helped with longer pre-infusion time. On my lever, I will pre-infuse at line pressure until I get even beading on the bottom of the basket and the first drops in the cup. For light roasts, I aim for about 15 seconds until first drop and 50-55 seconds total brew time.
Eventually you will end up with a lever.

LMWDP #706

User avatar
another_jim
Team HB

#3: Post by another_jim »

Light roasts require substantially finer grinds. Don't be afraid of choking the shot, dose at a weight that produces a very slow flow just this side of choking. The grind should not be as fine as Turkish (like powder without granularity) but it should be the finest granularity you can get.
Jim Schulman

Maggiekw (original poster)

#4: Post by Maggiekw (original poster) »

I can try that tomorrow. I allready preinfuse like you suggest. Bringing the pressure up to 8 bar when the first drops comes. That usually take around 15-20 secunds. Still channeling.

When you say up the brew ratio, you think more then 1-3 ratio? My experiance to now is that doing that will only make it less bitter and giving it a very clear and strong acidity. Missing the sweetness.

Will take some videos tomorrow to show you

Maggiekw (original poster)

#5: Post by Maggiekw (original poster) »

another_jim wrote:Light roasts require substantially finer grinds. Don't be afraid of choking the shot, dose at a weight that produces a very slow flow just this side of choking. The grind should not be as fine as Turkish (like powder without granularity) but it should be the finest granularity you can get.
So you suggest grind so fine that its like thick soup coming out and take it to a ratio, say 1-2.5? For me that just sound super bitter, but I havent tried that yet

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CoffeeMac

#6: Post by CoffeeMac »

I've gone as high as 1:3 to tame very acidic roasts (eg Chromatic). But I'm usually able to keep at a 1:2 ratio with higher PI pressure (which effectively translates to higher brew temp on my Compressa), finer grind, superfine basket, 19g dose (vs 18g normally)
Eventually you will end up with a lever.

LMWDP #706

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another_jim
Team HB

#7: Post by another_jim »

Maggiekw wrote:So you suggest grind so fine that its like thick soup coming out and take it to a ratio, say 1-2.5? For me that just sound super bitter, but I havent tried that yet
As Coffeemac says, longer ratios are sometimes useful. Light roasts don't have much bitterness, so finer grinds can't hurt. They can have a bright cutting flavor, something between cardamum and lemon zest, along with the acidity. In that case you want a very lungo shot.
Jim Schulman

K7

#8: Post by K7 »

I find Kenyans are often tough to work with. If super fine grind to choke and long preinfusion don't work, you might want to try the other way: fine grind, but not too fine to cause choking and require long preinfusion, and gentle pressure (maybe even 4 bar) with 1:2.0 to 1:2.6 ratio in 20-25 sec including normal preinfusion (~7 sec). Crema and mouth feel may degrade but I get great flavors with clarity. As you noted, the key is to avoid obvious channeling which always tastes bad (sharp and bitter, often sour as well). Works for me but YMMV.

Maggiekw (original poster)

#9: Post by Maggiekw (original poster) »

I went to my local roaster again today to ask them about how they do it. They had an low ratio with 22g in and 30-32g out in about 30 secunds. With that in mindre i went home to try again.

I grinded a little bit finer and upped my dose to 20g instead of my usual 18. I added preinfusion to lower the risk for channeling. Then I increased the pressure to around 4-5 bar. And aimed for a yield of 30g. The time wasn't that importent. The taste was alot better. Acidity was present, but in a nice and soft way. A little bit of bitterness, but also in a nice way, and alot of sweetness and body.

The next shot i grinded even finer and by a mistake upped the pressure alittle bit after preinfusion to 7 bar. I noticed a increased channeling and the taste was quite different. Still a good shot i think, but less bitterness and more acidity. The last shot was more like the one you get at the local roaster. Do someone have a suggesten of why this shot tasted less sweet and and more sourness/fruity? It was not unpleasant, but the first one was better. Is it because of a bit more uneven extraction, higher flow pressure or finer grind? Or a combo maybe?

For my last shot I grinded alittle bit coarser, but finer then the first shot, then repeated everything from the first shot and this is the shot in the youtube link in the bottom.

Im happy with the taste and im feeling i got control of the shot now. It tasted alot like the first, maybe a little bit more fruity now. But im not satisfied with the look of the shot and think that I can get a even better shot if it was more even. The first shot was a little better as it all went down in one drop(?) instead of 2 like in the video. There is also spots without extraction as you can see. I think the puck looks good and I really try my best to make it as fluffy, flat and similar everytime. Is it me that are just to much of perfectionist, or how can i maybe get it better? I have ordered a new wdt tool to try that (the one i have now dont go out to the edge of the basket in a way i want), and the ims 200 shower screen

YOUTUBE LINK:











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CoffeeMac

#10: Post by CoffeeMac »

It's hard to say from the photos, but I think you are on the right track in terms of process. Vary one parameter at a time (dose, grind, PI time, pressure) and see how it impacts taste. Once you get recipe that tastes good to you then aim for consistency, perhaps making small tweeks on process or recipe to continue to fine-tune. Soon you'll start to build some intuition on how your machine and recipe parameters influence flavor. Then repeat process for radically different styles of beans (Neapolitan, medium, filter, washed vs natural, etc,).

I spent the first month with my new machine doing this (burning through more than a few bags of beans) and built up a lot of insight into how to get good results on a new bean; I can now usually get dialed in within 1-2 shots.
Eventually you will end up with a lever.

LMWDP #706