Kenya Nyeri Ichuga Factory
Beans: Kenya Nyeri Ichuga Factory
Varietal: SL-28, SL-34, Ruiru-11
Elevation: ~1800 masl
Process: Washed
Retailer: Sweet Maria's
Pre-Roast Weight: 231 grams
Roast Attempt: 40th
Roast Date/Time: August 1, 2021, 1400 CDT
Nyeri is a county in central Kenya's highlands, and a lot of the best Kenyan coffee comes out of it. If I remember right, the first coffee my dad sent me when he started roasting was a Nyeri AA, and it was excellent. This lot is actually a mix of AB and peaberries - the smaller bean size of the AB grade means you can mix them with the peaberries without running much risk of having significantly different roast times (as opposed to if you tried that with the larger AA beans).
As usual, I started the roast on the one-pound setting to give me 18:00 on the timer, with manual control and 100% power to the heating element (P5).
Chamber Temperature
16:00 - 140
14:00 - 215
13:00 - 240
12:00 - 266
11:00 - 284
10:00 - 273
I recently watched a Sweet Maria's video about keeping the Behmor clean and they talked about how the chamber thermistor is right behind the side wall, so if you let residue build up on the walls it will be less sensitive, give lower readings, and thus roasts will take longer. I will confess to not totally understanding this logic - at least as far as manual roasts go. Wouldn't this just mean that first crack would start occurring at what seem to be lower temperature readings? The interior of the chamber isn't going to be less hot just because the thermistor is reading low. Roasts take longer because lower heat means it takes longer to finish the beans. At any rate, given the consistency with which I've had lower readings since moving to Chicago, I continue to think the issue is simply one of power to the machine. But no matter, because I've still been managing to achieve solid results, even if it takes slightly longer.
I increased the drum speed at the yellowing stage, which was around 10:00 on the timer (8:00 into the roast). Yellowing always used to happen pretty much right at 10:30, but it's been getting a bit later, especially on larger beans.
Exhaust Temperature
10:00 - 195
9:00 - 276
8:00 - 314
7:00 - 338
6:00 - 352
5:00 - 366
One thing I've picked up on lately is that first crack seems to be occurring around an exhaust temperature of 360. The very beginning of first crack is supposed to happen at about 385, so it's interesting to note how relatively close the exhaust temperature is to actually tracking bean temperature. Looking back at my notes, though, first crack frequently used to happen more around an exhaust temperature - or maybe I should say an exhaust temperature reading - of 370. So that could be an issue of a thermistor being less sensitive. With that said, a lot of recent first cracks simply have happened at later times, which suggests less heat.
This one hit first crack at 5:45, which is fairly normal based on what I've observed in history. (This is still only my 40th roast, as mentioned above, so "history" is a loose term, but still.) First crack lasted about 60 seconds; my pre-roast intention was to hit cool right at the end of the taper, but with the A temp still in just the low 370s I decided to hold back a little and gave the roast 30 more seconds, hitting cool at 4:15. The A temp peaked at just 379, shortly after the start of the cooling cycle.
Complete Roast Time: 13:45
Post-Roast Weight: 200 grams
Loss Percentage: 13.4%
Definitely a good percentage. We should be looking at an easy medium, maybe medium-light, which is what I would want from this origin - and a bean description from Sweet Maria's that suggests notable levels of acidity.
These were the beans on Wednesday, three days off roast. Color definitely looked more to the medium-light side; at the immediate conclusion of the roast it had looked a little darker, although considering the mild variability in bean size it does differ a bit across the roast. I ground to 3/4 coarse in the Capresso, and then used 60 grams of ground beans and a liter of water in the Chemex. The brew took about six minutes and produced 32 fluid ounces of brewed coffee.
TASTING NOTES: This was a notably bright and acidic coffee, with a big hit of tart grape right from the outset. From there, the profile continued making me think of wine - it was tannic all the way through, but retained enough juiciness in the body that I continued to think of wine as opposed to tea. A few chocolate notes emerged in the middle, but the overall flavor was heavy on "fermented grape."
VERDICT: Most acid profiles in coffee are either dominated by citric acid or malic acid, the two main acids in fruit. This one might actually have leaned more towards tartaric acid, which is the principal acid in grapes and especially red grapes. The extent to which this coffee made me think of a glass of wine - Sweet Maria's compared it to Zinfandel - was kind of amazing; indeed, aside from the brief appearance of some mild chocolate notes, and the fact that it was hot and non-alcoholic, there was hardly anything to make one think of "coffee" at all, as opposed to wine or tea. I always find coffees like that very interesting, although I don't think I could say this was one of my very favorites - too much taste of grape skins. It wasn't bad, but I was left wanting a bit more. I'm thinking of what I might do with the second half of this batch - if a full roast time of 13:45 left it this bright, I might try adding another 30 seconds or so, taking the A temp into the mid 380s, and just seeing if I can roast out a bit more of the acidity and get any other flavors to develop. I don't normally do repeat posts on the same batches, but if the profile is markedly different the second time around I may come back to discuss it.
Interesting result
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