Can you help improve my light roast extraction (Cafelat Robot)

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brainero
Posts: 5
Joined: 1 year ago

#1: Post by brainero »

Hi all,
TL,DR video:
I've been taking espresso more seriously since buying my robot last october. Currently pretty confident with medium roasts and dark roasts (though I generally only do dark roasts to make cappucinos for my girlfriend). I tried a new coffee roaster recently and the beans were a heck of a lot lighter roasted than anything I'd come up against until now. I have a 1zpresso JMAX hand grinder and these were also the first beans that really wrecked my wrists while grinding. I'm almost 1000g through these beans, and the hand grinding is getting more doable, but it's very clear to me, just from the grinding, how much different these beans are than the others I've used.

So after 800+g of beans I'm still not satisfied with the espressos I'm making. I guess that isn't very surprising. But I took a video and I was wondering if maybe some of you have some insights into what I can do better. As far as I can tell, the biggest things holding me back are channeling and maybe temperature. I have tried to really preheat everything, but that's still not enough to take the acid bite out of the coffee. Since it seems to me like the channeling is still an issue, I'm currently just doing a double pour, and figure once I really get the puck prep right, I'll go back to optimizing the temperature. I do WDT as thoroughly as possible and try to make the coffee as level as possible before tamping. I tamp not too hard, just enough to properly compress the grinds. This is something I'm really unsure about but usually I've experienced more channeling when I tamp harder. This video is the best shot I've had so far, actually tasted pretty decent, but still not something I'll continue drinking if it can't get better. It's 15g in, 37g out, ~8 seconds preinfusion, ~33 second shot total. I extract at like 4-5 bar. So far that's been the best at keeping the flavors more mild / balanced and reducing channeling. Although I've tried a lot of stuff, like grinding way finer, 30+ second blooms, 80+ second shots...

When I do medium or dark roasts the extraction is ... clean. Nice even preinfuse with coffee covering the whole basket bottom and then a nice clean stream until the end. Not like this. So I guess...can it get better? Does the extraction need to be prettier? Do I need a different grinder?
Anyways, I really appreciate all feedback :)

Ben

lessthanjoey
Posts: 362
Joined: 4 years ago

#2: Post by lessthanjoey »

Light roasts are lower body, there isn't anything super concerning about the bottom of your portafilter during the shot. It's maybe a bit off center but I can't tell for sure.

Is the bottom of your puck evenly colored post-extraction? If it's darker on one side that's definite puck prep unevenness. If it's just mottled with black spots, some combo of better WDT and probably grinding coarser and flowing faster will help that.

However, your main comment was that the coffee was acidic. That sounds right! Light roast coffees are vastly more acidic than medium-dark coffees. As you roast darker you reduce acidity, but also reduce fruity and floral flavors. As you roast lighter you preserve acidity along with those fruity and floral flavors.

You didn't say where this coffee is from, but some origins and varietals will be more acidic than others. Brazilian coffees are in general going to be some of the lower acidity coffees you can get (but will also generally be more nutty than fruity/floral.

Finally, water makes an impact. What is your water? If you can increase KH/alkalinity, that'll buffer some of the acidity and take some harshness off, but pretty much all light roast espresso will still present brightly. Which comes back to the main point - what do you want your coffees to taste like? What drew you to this coffee as a light roast for espresso?

brainero (original poster)
Posts: 5
Joined: 1 year ago

#3: Post by brainero (original poster) »

Great reply. Thanks! First, the beans: https://shokunin.coffee/product/churupampa/
I got these because I liked the description. Heavy body like dark chocolate -- yes please! Nutty? Yes! The roaster says everything they do is an omniroast so I assumed it would be good for espresso. I've done medium roasts that were maybe on the light end of the spectrum before, needed to do like a long bloom to get rid of the sourness, and then they were delicious. I guess when I say acidic, I'm happy with some acidity but the bad ones (and I got a lot of these with these beans) really bite. I would call that sour, not acidic.

I really really like the flavor of these beans. With my hario switch it's easy to get them to taste right. They make all medium-dark and darker roasts incredibly boring in comparison. But it just feels like I'm not quite there. Good to hear that the bottom of the portafilter looks alright though. Or bad I guess, since that means there's nothing to improve in that department. I'll try an even coarser grind though.

I'll get a pic of the puck tomorrow morning but it looks pretty evenly colored as far as I can tell.

Yeah the stream is often a bit off center. I'll grab my level and check that it's not due to my table. It's always in the same spot when I notice it.

I've never looked at my water. Thought to not look at alllll the variables all at once. I don't have the tools to measure it but according to the water supplier, at my postal address (Netherlands) it's quite soft. Specifically, 4,6 dH. It's also practically neutral. ph of 7,89. So I guess you're saying my water isn't buffering that acidity at all (if I understand you correctly)?

lessthanjoey
Posts: 362
Joined: 4 years ago

#4: Post by lessthanjoey »

4.6dH hardness is ~80ppm, so not super soft for espresso, but "reasonable". Alkalinity/buffer in this sense isn't the pH of the water, but "Carbonate Hardness" which is carbonates and bicarbonates, so need to look it up separately. You can try adding some (baking soda is a common source) if you want to experiment (about 0.08g/L) and see if that makes much of a difference for you.

Since you like it as filter, it's worth seeing if you like these shots as Americanos too - just dilute out to a similar strength. If you do, then it's that acidity balance at espresso strength that's the issue for you and perhaps the buffer will help.

Alternately also try pulling a longer ratio, maybe 15:45 and see if you prefer that.

51M0N
Posts: 13
Joined: 2 years ago

#5: Post by 51M0N »

When you say preheat everything, does that include the piston? I found that this made the biggest difference to me with light roasts.

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MNate
Posts: 959
Joined: 8 years ago

#6: Post by MNate »

Your technique looks great.

Many in the Decent community do turbo shots for lighter roasts, which is basically just saying fast flow. I like it and use it with my robot too, at times. May be worth a shot.

Grind quite a bit more coarse so you are at more like 4 or 5 bar and your shot only takes 15 seconds including a very short preinfusion. It will look messy, not perfect like yours now, but the taste will be quite different. You may like it. You may not. But it's easy to try, hard to do wrong even if some of those parameters are off.

brainero (original poster)
Posts: 5
Joined: 1 year ago

#7: Post by brainero (original poster) »

Thanks everyone.
lessthanjoey wrote:4.6dH hardness is ~80ppm, so not super soft for espresso, but "reasonable". Alkalinity/buffer in this sense isn't the pH of the water, but "Carbonate Hardness" which is carbonates and bicarbonates, so need to look it up separately. You can try adding some (baking soda is a common source) if you want to experiment (about 0.08g/L) and see if that makes much of a difference for you.

Since you like it as filter, it's worth seeing if you like these shots as Americanos too - just dilute out to a similar strength. If you do, then it's that acidity balance at espresso strength that's the issue for you and perhaps the buffer will help.

Alternately also try pulling a longer ratio, maybe 15:45 and see if you prefer that.
I'll try the acid buffering soon. Seems interesting. So far the longer ratio doesn't seem to make it better, just more watered down.
MNate wrote:Your technique looks great.

Many in the Decent community do turbo shots for lighter roasts, which is basically just saying fast flow. I like it and use it with my robot too, at times. May be worth a shot.

Grind quite a bit more coarse so you are at more like 4 or 5 bar and your shot only takes 15 seconds including a very short preinfusion. It will look messy, not perfect like yours now, but the taste will be quite different. You may like it. You may not. But it's easy to try, hard to do wrong even if some of those parameters are off.
51M0N wrote:When you say preheat everything, does that include the piston? I found that this made the biggest difference to me with light roasts.
So I tried it a little bit coarser, more like a turbo shot, and went back to preheating the piston. That basically seems to have done it! Stopped the shot right when it really started to channel hard, like how I did in the video. As long as the stream was steady I kept pulling...ended up at 37g again but this time in about 18 seconds. I was definitely not thinking about making it even coarser before, as it felt like a pretty fast shot already, especially compared to the medium roasts I've pulled, but I guess fast and hot really is where it's at for light roasts..

I just need a more efficient way of preheating the piston. Currently putting a tall glass under it but that wastes like 300ml of hot water.

lessthanjoey
Posts: 362
Joined: 4 years ago

#8: Post by lessthanjoey »

Glad you got results that you're happy with! I'll just note that you changed at least 2, if not 3 things, so probably worth testing them independently to understand what the key piece was:
(1) Increased temperature
(2) Increased flow rate (ground coarser)
(3) Maybe stopped at a shorter ratio? You mention stopping when it started to "channel hard", but likely that's just when flow rate increased and body was low enough that it got messy. Was the output weight more or less or the same as before?
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Miltonedgebert
Posts: 93
Joined: 2 years ago

#9: Post by Miltonedgebert »

I preheat the piston by pouring water in from the top. I picked it up from someone else on this forum and it's the easiest preheat method I've tried.

brainero (original poster)
Posts: 5
Joined: 1 year ago

#10: Post by brainero (original poster) »

lessthanjoey wrote:Glad you got results that you're happy with! I'll just note that you changed at least 2, if not 3 things, so probably worth testing them independently to understand what the key piece was:
(1) Increased temperature
(2) Increased flow rate (ground coarser)
(3) Maybe stopped at a shorter ratio? You mention stopping when it started to "channel hard", but likely that's just when flow rate increased and body was low enough that it got messy. Was the output weight more or less or the same as before?
Good points -- I did both at once since I had already been doing the piston preheat previously, and it was a lot of trouble for something that didn't seem to help too much. I thought the issue was my puck prep since I thought I was channeling everywhere, so I figured I'd focus on that first. I'll try both recipes with the piston preheat again to be sure.

I guess that point that I'm mentioning seemed like a good spot to stop since I thought I was just going to be adding bad flavors to my coffee. I'm used to often stopping based on how the shot looks rather than sticking to a ratio. But the shots were really similar both times; 15g in, ~37g out, just this time it was a lot faster.
Miltonedgebert wrote:I preheat the piston by pouring water in from the top. I picked it up from someone else on this forum and it's the easiest preheat method I've tried.
Ooh, thanks...you don't worry about getting water stuck inside the piston?