Here's another quick experiment I did, comparing a 75% airflow roast with one where I maxed airflow out the whole time. Consistent with some expert recommendations, the 100% airflow roast seemed to flatten out the acidity and stripped away some of the subtler flavor notes. There were also just a bit more tannins in the finish on that cup. Detailed notes follow below.

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Roasting Info: 75% Airflow Roast:

Bean: Kenya Gichugu
Roaster: USRC Sample Roaster
Charge Mass: 333g
Charge Temp: 390F
Dry/Ramp/Development: 3:25/3:23/2:24
FC-start temp:371F
Finish Temp: 388F
Overall Roast Time: 9:12
Moisture Loss: 14.11%

Profile Plot:



[BT=Red (ROR = Fainter Red Line), Exhaust=Green, Gas=Blue, Fan=Yellow]

Tastify Scoresheet:



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Roasting Info: 100% Airflow Roast:

Bean: Kenya Gichugu
Roaster: USRC Sample Roaster
Charge Mass: 333g
Charge Temp: 390F
Dry/Ramp/Development: 3:15/3:07/2:16
FC-start temp:370F
Finish Temp: 388F
Overall Roast Time: 8:38
Moisture Loss: 13.81%

Profile Plot:



[BT=Red (ROR = Fainter Red Line), Exhaust=Green, Gas=Blue, Fan=Yellow]

Tastify Scoresheet:

Great notes; very detailed.

Will roast the Kenyan next week (note to self). Kenyan will be stocked, on the shelf, and posted on the website by Wednesday. Brazil was re-posted last week.

Dave

I'll add before Mark moves us along toward flavors Brazil that the Kenya has been delicious tome by both low-med and med to high med roast profiles. Today I pulled a shot of the higher airflow roast of mine that was tart cherry and very much enjoyed.

IDK, Flint, my palate could be different from yours, and to be honest I was not that fond of this Kenyan. After my initial evaluations, they were sitting in my shelf for 2 weeks and I always picked other coffees to drink. I kept searching for a "main theme" in this Kenya, be it sparkling acidity, sweetness, or full strength body, but couldn't find any. To me, it also lacked the complexity; the flavors didn't evolve sip to sip.

I've tried two more batches, brining them into a darker side. Stay tune.

I personally really liked my higher-airflow roast. It had the classic Kenya flavors, pungent bordering on weird, but not actually weird vegetal stuff.

9Sbeans wrote:IDK, Flint, my palate could be different from yours, and to be honest I was not that fond of this Kenyan. After my initial evaluations, they were sitting in my shelf for 2 weeks and I always picked other coffees to drink. I kept searching for a "main theme" in this Kenya, be it sparkling acidity, sweetness, or full strength body, but couldn't find any. To me, it also lacked the complexity; the flavors didn't evolve sip to sip.

I've tried two more batches, brining them into a darker side. Stay tune.

That is always true. It would be a real kick to taste espresso and pourover with persons as into coffee as the forum members, but I rarely get that opportunity.

As far as this coffee, I pulled another shot this morning, using the lower airflow. It was the closest thing to sour cherry I can remember in the small cup. I never put sugar in my coffee, but I think I will try it with this one just to see if sugar turns it into cherry pie filling.

jalpert wrote:I personally really liked my higher-airflow roast. It had the classic Kenya flavors, pungent bordering on weird, but not actually weird vegetal stuff.

Agree, not actually weird vegetal stuff.

My overall impression of this Kenya is that, the acidity is not at the higher end (lemon); instead it's more of apricot like. Big, malt-like sweet dry fragrance, but I couldn't get the sweetness taste into the cup. Thin body, no vegetal pungent, only rounded taste. This Kenya got better structured in a slower 13-min profile (my batch #4). So far, your summary (post #19 on page 2) still holds true. I prefer the increasing/higher airflow approach.

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Roasting Info:

Bean: Kenya Gichugu, #3, 14min FC roast, low heat, low airflow
Roaster: KapoK 500 Sample Roaster
Charge Mass: 261.6g
Charge Temp: 310.1F
Dry/MAI/Development: 5:15/4:42/4:00
FC-start temp: 374.9F
Finish Temp: 399.4F
Overall Roast Time: 13:58
Weight Loss: 15.25%

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Roasting Info:

Bean: Kenya Gichugu, #4, 13min C++ roast, increasing airflow
Roaster: KapoK 500 Sample Roaster
Charge Mass: 261.3g
Charge Temp: 309.9F
Dry/MAI/Development: 5:05/4:34/3:10
FC-start temp: 374.9F
Finish Temp: 396.4F
Overall Roast Time: 12:49
Weight Loss: 14.66%

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12/8 updated:

In my batch #3, I played with the combination of low fan, low heat and long roast time. (35 Minute Roasts?!) It had nice nutty dry fragrance when grinded, but was undrinkable as drip. It's a bipolar cup: a little bid sour and a lot of bitter; thin body, no flavor, no sweetness, nothing else to bridge the acidity and bitterness. For SO espresso, I've tried several extraction parameters, and the cup was palatable when warm. However, the unpleasant dry distillate aftertaste was too strong and eventually I decided not attempt to savage these beans.

Although my experiment on batch #3 was not successful, my findings corroborate Mark's observation on post #55. ( Roast and Learn Together - November/December 2015 ). When airflow is locked in a constantly low rate, it is very difficult for me to maneuver through a roast by simply controlling the gas, the dip and flick is more pronounced, and this roasting flaw results in unbearable dry distillate aftertaste.

My batch #4 (intended for SO espresso) was surprisingly good as drip. Although the acidity was muted due to higher drop temperature and longer roasting time, the body was better developed and yielded much balanced flavors. The SO espresso had big, rounded typical Kenyan aroma and flavors, and it was sweeter than my batch #1 & #2. I personally think that the "in-the-face" aroma is catchy but monotony, and now I'm blending this batch with some other Costa Rica or Rwanda beans as espresso.

I agree that the vegetal & tomato notes that one gets with some Kenyans are absent here; when done right, this one offers a simple, crowd-pleasing cup, rather than the edgier notes that some good Kenyans can present. My best roasts have some pleasant florality, stone fruit & tropical acidity, and a sweet, smooth finish. I've also found that it is quite sensitive to profiling choices, with poor roasting choices leading to the emergence of tannins that drown out the sweetness, or flattening the high notes.

I'm going to do one more roast with it in the next few days, focusing on isolating the impact of increasing airflow compared with flat airflow approaches, and then move on to the Brazil.

Tom I did what you suggest last night with a Kenya Nyeri I had in my inventory, but haven't cupped it yet.

Could we have a discussion about what to do with this Brazil? I rarely roast less dense beans and I don't really have a sense for what a typical approach would be, other than "go slower." It would be super helpful if anyone could provide just a few comments regarding how low-grown beans should be approached vs. more dense beans. Thanks!