mkane wrote:This was culled from 400grams. And I bought 10 pounds of this.
image

And I culled another 400g of this coffee and the visual defects doubled in size.

Luca, there's a couple of flatlines in the profile you posted that lasted 40 sec or so.

LuckyMark wrote:Totally agree. The intent of the thread was lost on many.

Upside is we now know who the best roasters are

Best is simply an opinion, nothing more... I'm able to crank out batch after batch that continues to impress me and that's all that will ever matter. For yrs I bought a lot from artisan roasters and just grew tired of how things have changed over the last 6-8 yrs. I get what greens I like, buy in bulk and store to save along the way, dial it in to suit my taste for espresso, do it when needed and save at least 50% in the process. So yeah, what I do is certainly the absolute best for my taste/use and I don't miss commercial roasted one bit!

mkane wrote:And I culled another 400g of this coffee and the visual defects doubled in size.

Luca, there's a couple of flatlines in the profile you posted that lasted 40 sec or so.

Yes the crash and stall around 1C can cause textbook roast defects exactly as he described in his flavor notes.

luca wrote:Allrighty, let me throw this one out to the floor.

I have this central american washed coffee that I have roasted a few times, 2020-2021 harvest, bourbon and typica, call it 1800 masl. I haven't tasted it for a little while, but my roasts have been pretty flat, kind of muddy and with a distinct, papery, flat quality to them. I'd expect this to be sweet, crisp and maybe to have some stonefruit to it.

I've got a good guess, but why do you guys think this coffee sucks? Did I screw up the roast? Entirely possible. If so, how? Or did I buy bad green? And, if so, what's bad about it?

Are you calling crack or is the ROEST doing it? ROEST won't mark it until the 5th crack IIRC. Did you do a batch size of 100g or 120g? What was your percent loss? Your turning point on the BT line is more rounded than I'd expect with how hot you're going and with how thin the ROEST probe is...does it look normal to you?

Overall, curve looks fine. In other words: good greens should taste good with this profile. Short roasts like these tend to fall outside the jurisdiction of strict Rao-ism.

My first thought is old greens. If harvest was more toward 2020 than 2021, I'd expect significant falloff by now unless you vacuum seal and freeze upon arrival. But don't old beans crack less and softer? Don't quote me on that. ROEST says you got a number of cracks. How come its crack lines have different heights, is it really measuring the decibels and giving taller marks for louder cracks? Normal crack temp and normal drop temp?

Looks like drum speed and fan are fixed. Those settings have worked before? Your charge temp normal for you? I'd be interested in knowing what other profiles you've tried with these greens and if those had the same taste defects. And the taste was papery and flat, not watery?

I'm happy to be wrong with any of my guesses. Fun thread. Don't tease us for too long. Let us know what your guess is.

Allrighty, I'll have a go ...

I'm less sure on this than on the easier stuff like the visual defects, and I may not have described it well, but you guys are all thinking exactly the same as I am. It's probably either baggy/old green or baked, and I'm leaning more towards old green. For two main reasons: (a) it's more papery than toasty, which sort of shows the limitations in discussing these things in words rather than us tasting the same thing and (b) it doesn't really seem to have any fruit at all; it's a very light roast level and very fast, so if I had baked it, I'd expect to still get at least some fruit; this is very flat. But I've got more of this stuff, so I'll give a shot to manipulating the curve to have the ROR decline more precipitously; I mean, what else am I going to do with it?
Wow, leave some question marks for the rest of us!

1. Auto marked by Roest and set to auto mark on the first crack it detects.
2. I've only done 1200 roasts, so I haven't settled on anything. I think that was probably a 100g roast, but at the moment I'm at 120.
3. Don't know what you mean by "more rounded".
4. The crack lines are their way of showing the number of cracks. So the shortest line is one crack, the next tallest is two cracks, etc. So with the taller line, the machine is telling you it heard two cracks in the same second. The lines really aren't that useful; I guess they do give you an indication of progression of the roast. For example, I have one natural coffee that cracks ludicrously early and has erratic and slow cracks over a long time; ethiopian coffees tend to give a million cracks in rapid succession, centrals give relatively few cracks, etc. The crack count that they have added is probably more useful than the bars, and it does seem to hold true that if you have significantly more cracks, the coffee tastes more developed/roasted.
5. Yes, paddle and fan speeds both fixed in this profile. They can be changed. Fan speed can be changed physically on the machine, but only in increments of 5%. RPM can only be edited from web portal, not on the machine itself.
6. Yeah, I think those settings worked for some coffees. But I'm using power profiles and leaving the end to be finished off manually, since different coffees crack at different times, etc. You can extract air temp profiles from logs, but not power profiles, unfortunately. And I don't like air temp profiles. Different coffees can require markedly different roasting parameters on roest, I think, at least. I've got a profile that I'm trying for washed ethiopian coffees with increasing RPM.
7. Yes, normal charge temp. Ish. I mean, you can roast from cold or from 250c and produce a palatable roast under either condition.
8. I think I've tried about two or three other roasts; can't quite remember what profiles, but all similar results in the cup. You're right to ask this - I think a general rule is just go fast and light and see if that gets rid of the problem; if it's still there, it's probably a green issue.
9. No, not watery. Why do you ask? What would watery tell you?

Looking at this graph, it looks like I overrode the profile with manual control early, being a little scared that it wouldn't get there. Probably needed maybe a bit more heat earlier and some more aggressive drops later. I guess?

OK, over to the next person if they want to play ...

Is there a delivery problem from where you're at? I mean, does everyone, in your neck of the woods have an issue with green coffee not being up to standard?

Hey Luca,

My simple take on the central with your descriptions from when I have encountered similar flavour notes. Pushing too much green with too much heat for the given environment over a short period of time.

I concede the green might not be top notch and likely start to show signs of age, as you say hard to know without sharing.

After reading your other notes again especially the weird stuff about cold starts, intuitively I can not see any point in the bean temp at charge being that much higher than your target end temp.

Your overall approach with the power fixed until about 1:30 before first crack start looks good and is inline with how certain pro roaster with the Loring and how they suggested I roast similar on smaller gas drum, which they also try to replicate what Loring does. I have made more progress with this technique and set up of the roaster, so i might update you after couple of weeks time. That Kenyan was a good example of not enough airflow and an inefficient roasting environment and as you say Kenyan can be forgiving in this regard probably due to size and density. On the other hand the smaller Rwanda ends up quite dark and still under done.

Maybe veering off topic here...
Re cap on above mentioned technique:
Just under max airflow
Find optimal burner output for that airflow which gives desired roast time with optimal batch size = brings out the quality acidity fruit, clean and nuanced cup.
(Around 50% with gas drum)

Because of much larger drum mass, my charge temp needs to be slightly higher than target temp. Joe Morocco's +/- 6 degrees Celsius of target temp seems to be a good guide.

With the stablised environment its a matter of running this optimal hot air stream until just before or around the start of browning / caramelisatiion. Less mass the longer you may need to hold on / or smaller gradual changes.

For my roaster in Celsius
Starting to yellow 150
Full yellow 155 - 57
Orange 163 - 165
Start brown 172 - 175 (at 50% capacity this is where first gas adjustment is made and ROR has magically declined on its own! If gas left alone this is where ROR will start to plateau and or incline slightly before first crack, resulting in explosive crack / crash / stall / bake / flick etc.)
First crack 187 - 191
50 sec to 1:15 development

For those joining us, Stephen and I have traded roasts and spent years trying to get good roasts from respective kaffelogics. Steve posted me an excellent slightly darker roast kenyan from his setup just last week, as well as a Rwandan that's in the ballpark.

Yep, might as well try a longer roast.

Remember that I have a stationary drum with the drum temp probe at the point on the stationary drum where the coffee would rest, were it not stirred. From memory, the 220c BT idling temp as the starting temp gets that point of the drum idling at about 20C less than the temp that it finishes at at the end of the roast. I've modded the machine to use that slot on the PCB for the inlet temp probe, so i don't have that graphed and displaying above.

As for the cold starts, I gave that a brief go after the kaffelogic session with Sam Corra at Ona, on blending. He seemed to think that start from cold was a benefit for the KL, perhaps because of repeatability. I plead ignorance on this point.

luca wrote:
Remember that I have a stationary drum with the drum temp probe at the point on the stationary drum where the coffee would rest, were it not stirred. From memory, the 220c BT idling temp as the starting temp gets that point of the drum idling at about 20C less than the temp that it finishes at at the end of the roast. I've modded the machine to use that slot on the PCB for the inlet temp probe, so i don't have that graphed and displaying above.

Hmm that's interesting, i had either forgotten this or failed to interpret originally. I would be interested to know the reasons for this design choice.