Hi Marshall. High heat for 3 minutes from the charge or from the turn?

I think Marshall means the first three minutes from the charge.

IIRC, he built his own fluid bed roaster, and its thermo mass is relatively small. (It is very interesting that distinct roaster type can mimic each other's profiles. We will figure it out this month. ) As I described in my previous post, KapoK (and I think USRC, mini-500, and TJ-067 should be the same) have greater drum thermo mass and transfer heats faster in the first three minutes. Due to the faster initial heat transfer, bigger drum roasters will have higher initial RoR. Since Rao suggests declining RoR, it's advantage (or, necessary) to have a fast start.

Huky and Quest have thin drum wall and may need to apply more heat in the beginning to achieve a high RoR.

Clint Orchuk wrote:Hi Marshall. High heat for 3 minutes from the charge or from the turn?

The turn might as well not even be discussed. It's instrument error. So, from the charge. Also, if you are blasting past 300F/150C before 3min, maybe either increase the bean mass or not so much heat...I don't know, that's just a thought that might be wrong. The profile in the Rao book is roughly 5min yellow, 8min 1C, 10min dump. Done perfect, the coffee will be very good. I personally prefer a touch faster, especially with Ethiopian coffee... although I really think the important take home is to reduce heat to avoid ROR standing still or increasing just before or towards the end of the crack; more than what exact times things happen. Longer roasts leave much less ROR to decrease from than shorter roasts, and short roasts can be a challenge to control, so there kinda is a narrow window of what actually works without stalling or baking.

My definitions, inspired by but modified from Perger's:
Stall: low or negative ROR that results in 1C stopping prematurely
Bake: ROR that increases after 1C starts

First shot at it last night. 230g. Low development temp wise from 1Cs to drop, I dropped off too much heat after 1C and ended up with minimal bean expansion. We'll see.



3/12- Kalita wave 16:1- 203°
Not much a surprise. It was amazingly sweet, floral and clean intense fruit, but mildly salty and a very short flavor experience before it just fades on the palate. Needs more development. I'll make a more thorough assessment on a better profile.

I roasted the Gedeo today at the end of my regular roast session. Temperature outside is nice, humidity normal, and the roaster was behaving predictably.

7Kg asymmetric hot air roaster, very much in the vain of Neuhaus Neotec. I generally believe my thermoprobe to be well placed, and very accurate. My numbers are probably as close to actual surface temp as any roaster could reasonably yield due to roaster design, thermocouple type, and placement.

My approach to this roast was one of minimal adjustment. Airflow was left alone from the beginning of my roast session hours prior. In retrospect, airflow was a touch higher than I would have liked. Both during the roast session and as a result of slightly overselling this coffee and not leaving enough for a full batch. Let's call airflow "medium /medium high". Fuel was set at "medium" and left alone until 10% development time had passed, at which point I slowly reduced it to a near but not stall, and dropped at 21%

12.15lbs in

100C @ 1:45
150C @ 3:30
200C @ 7:30 (1C, audible, visible, obvious, strong)
205C @ 9:30 (drop) a few crackles remained. I think I could have given a bit less development in retrospect.
Room temp in 3min.

12.7% weight loss.

Straight from the roaster, an EK43+V-60 brew at 19% extraction, 1.30% strength reveals a classic Yirga Cheffe profile. Dry fragrance is grahm cracker and marmalade. The black tea notes are vivid with a gentle citrus note in the background and fleeting lemon aroma. Body is delicate but slick. Aftertaste reveals a touch of bake, which I'm going to attribute to excess airflow leading to a stretched middle section, leading to my decision to not reduce heat leading into 1C; the ROR had flat-lined for 30seconds leading into the crack, hence the bake.

Had I another shot at this, I would have reduced airflow a touch. 150C would have likely came at about the same time for the medium heat input, but the momentum would have continued so I could have dialed it down without stretching the roast any further. Overall, this cup is really stunning... but I'm always looking for better.

16hrs post roast: 36g/600g Baratza Encore+Chemex
Again, the tea notes are prominent. Body and sweetness are a bit thin to my preferences, but fall in line with this cup profile. Body grows a bit as cup cools, florals and acidity are present, but much in the background.... a hint of orange juice. I'm not getting as much liveliness as I'd like. Cup is clean, but the finish is drying and there is the ever so subtle bake note late finish.... I doubt anyone who is not particularly sensitive to it would notice.

24hrs post roast: 20g/40g EK43+GS/3
Surprisingly full bodied shot, well tempered acidity leaning towards too mellow. Heavy chocolate notes with baking spices and browned sugar. The shot just kept extracting thick all the way to 40g, and probably had more sweetness in there, but that was certainly plenty.

48hrs post roast: 20g/300g Encore+Chemex
Oops, meant to do 333g pour. Anyways, holy cow! This slightly updosed cup (67g/kg) is huge and fat with pungent florals and chewy body. Tangible tangerine acidity comes second to immense sweetness. Far wetter on the tongue than previous days with the baked element having receded to the edge of perception.

72hrs post roast: 36g/600g Encore + Chemex (high but not measured extraction. guessing 24%)
Buckets of chocolate with notes of jasmine and lemon. Layers of depth. Syrupy body. Lingering sweetness and aroma. An ever so perceptible hint of bake in the occasional and fleeting whiff of harshness. Among if not the best cup of this Tea/Lemon/Chocolate Yirg cup profile I've had.

1 week off roast: 24g/400g Ecore + Chemex (probably 22%?)
This is about the most mouth filling coffee in recent memory. Baking spices and mandarin oranges in syrup. Acidity is vivid but not tactual. There is nothing I would change with this cup. This is convincing coffee.

Added tasting notes to my post, March 10.

Roaster - Hottop B-2K with variac and TC4C

Roast #1
I targeted a drop at 2:00 after start of first crack, or temp of 1C+25 F. 30 seconds after first crack started, I reduced the heat to 20%.

===========================================================================
Roaster - Hottop B-2K with variac and TC4C

Roast #2
I targeted a drop at 2:15 after start of first crack, or temp of 1C+25 F. 30 seconds after first crack started, I turned the heat and the fan OFF.

NOTE - my thermocouples read 30 degrees lower than most others. As noted in this post at Sweet Maria's, I have virtually identical readings as Barrie. We both have identical Omega probes installed in the same location on our Hottops.

Evaluation
I had two Hario pourovers to evaluate these after four days rest. Sometimes it is hard to detect a difference, but not this time. The second roast with 2:15 development was clearly better than the shorter first roast (which tasted under-developed). This is a VERY nice Yirg!

I'll preface this to say that I probably should have Lurked and Learned while we work to get our roaster setup working with ease. (If I had, the graphs here would probably look better) (Trying to configure TC4 and LCdapter with fan control (working well) then switch to a Linux system for our dedicated roaster computer has led to some long setup times.) I had to give up on the Linux box for now and use the Macbook for our roast session yesterday. But this Gedeo was too appealing.

So here is our R & L entry:

HUKY500 powered with gas powered stove TC4 slider fan control. ET is actually the MET probe outside the drum - (I am trying to put together a digital ET probe to replace the analog stock.) We set to fan (S on the graph) 60% on the slider, P marks changes in heat within the very low end of one of his range burners

We tried to follow Marshall's recommended high heat x 3 min then control RoR with gradual heat decrements, dropping at 23% (actually hit 22 according to the curve.)


and in Fahrenheit:

Day of roast evaluation was an aeropress cup, 20 minutes post roast. We agreed free of defect and roast, tea-like, mild, some sweet notes neither of us could name. I'll work on further evaluation notes while enjoying the coffee this week.
Cupped 2 days post roast: Very similar mild character, chocolate, hint of lavenderish bergamot something.
espresso shot day 3: sweet touch of bergamot still too mild somehow; pulled ristretto day 4 most chocolate of the shots.

EDIT: profile added after March 22 roast session. I need to gain more understanding of the Artisan software for outputting graphs.
For the second roast of the Gedeo, we tested taking the same parameters for use with a greater charge mass, 454 gram beans. Comparing to the roast #1 the dry phase is longer, ramp more agressive, same drop temp, but somehow the beans have a bit lighter color.

Chert, if your red line is MET, which is clearly is, I think your yellow line (Delta ET) is actually Delta MET.
Not that it matters.
But...It would probably be useful if you set Artisan up to give you Delta BT either in addition or instead.
The data is in your .alog file, so if you just re-configure Artisan it should show up.

Thanks. I really like that about the alog files. you can convert C--> F etc. But until I have a digital probe for the ET position on the Huky I can't show ET. I tried to use channel 3 and have Artisan display MET, but that also did not work. Still ironing some technical roastscope details, but I'm encouraged that I'll get there.