[creative nickname] wrote:Sounds like a reasonable summary to me. I should probably do a test where I max out airflow to see if there is a point past which more airflow becomes detrimental. I have heard a few pros claim that too-high airflow strips aromatic notes out of coffee. I think I'll try that this weekend ...

I will be doing some comparisons as well this month.

Sounds good, that will be interesting. I wrecked my 3rd batch of this coffee last night, so once I order more from Dave, I'm going to play with airflow settings in the drying period.

Based on some experiments I ran last night, my funky tabletop RoR graph in drying can be cured into a more typical "declining RoR" shape with greater airflow early on, so I'm wondering if that will help or hurt.

P.S. I've also got a bit of astringency in my roasts now, probably from the dip and flick, though they are still tasty. Will have to manage that as well.

I ran an experiment on airflow using a different coffee, but it still seems appropriate here.

Coffee was an Ethiopia Agaro Duromina from Sweet Maria's. All roasted on my Huky with PERFORATED drum, 48rpm.

Roast 1: hot charge temp, airflow on high the entire way, decreasing flame


Roast 2: lower charge temp, airflow on high the entire way, decreasing flame


Roast 3: mid-airflow to start increasing to high, decreasing flame


Roast 4: low airflow to start increasing to high, decreasing flame


Results were cupped blind at 24h post roast by me and my dad.

Roasts 3 and 4 were by far better than 1 and 2.

3 was the best when hot with great syrupy body and citric acidity, and 4 was the best when cool with a full body and malic mid-palate acidity.

Roast 1 (the screwup roast) was woody, thin, and generally flawed. Roast 2 had thin body, no acidity, short finish, but decent sweetness.

Of note is that the prettiest declining RoR graphs produced the worst results on my perforated drum. High early airflow on my setup produces the prettiest graph, and substantially poorer coffee. This is probably different for solid drums (?).

I'm trying to learn with this effort as well. My first two roast show some challenges I still have with controlling the targets, I chose to hold the drop temp stable rather than hold % development stable. I have another 500 grams available to try to improve the cup after I taste these over the next few days.

One observation from my effort is that the higher airflow stretched out 1C.

Roasting Info: Low air 15% to start 35% at pre-first crack and on (190C on my BT):

Bean: Kenya Gichugu
Roaster: HUKY solid drum with a perforate shield 2 cm below the bottom of the drum.
Charge Mass: 300g
Charge Temp: 460F
Dry/Ramp/Development: 4:45/3:48/1:48
Finish Temp: 414F
Overall Roast Time: 10:21
Moisture Loss: 14.3%



Roasting Info: High air. 15% to start until 1 min when I add heat usually then 35% until at pre-first crack 55% and on (190C on my BT) Airflow Roast:
Bean: Kenya Gichugu
Roaster: HUKY solid drum with a perforate shield 2 cm below the bottom of the drum.
Charge Mass: 300g
Charge Temp: 459F
Dry/Ramp/Development: 4:27/3:33/2:12
Finish Temp: 414F
Overall Roast Time: 10:21
Moisture Loss: 14.7%



Sorry my graph titles are goofed up.

I did not get a strong impression of either roast, but to me, cupping blinded, the higher airflow had more fruit. and a bit more punch of winey acidity.

second day impression of a cupping just challenges me to try harder to find the nuances in the cupping. I like both, some thinness of body, aftertaste lingers with berry, acidic pleasantness.

Jeff, thanks so much for sharing your perforated drum experiments. I agree that it may be hard to generalize results from solid to perforated drum, or vice versa.

Flint, thanks for sharing, and for communicating your approach so clearly.

My pleasure and opportunity. Trying to cup the samples raises a question for the more experienced. If I can't get cupping into a strong skill, then roasting is unlikely to improve. (I do know a winemaker who drinks no alcohol and his wine is pretty good...)

Are you confident that the aftertaste is from the cup just supped? Or should a palate cleansing go on between slurps to make sure sample A did not contribute to the aftertaste enjoyed after sample B, for example?

That's a great question. I vary the amount of palate cleansing between sips, with only a little being used for initial tasting impressions like body or acidity, but with more of a break between slower building impressions such as aftertaste, balance, and overall cup quality.

Chert wrote:...

Are you confident that the aftertaste is from the cup just supped? Or should a palate cleansing go on between slurps to make sure sample A did not contribute to the aftertaste enjoyed after sample B, for example?

Chert, it comes with time and experience. Cup, cup, cup. The more you go after it, the clearer it becomes that you are experiencing a specific taste from an individual cup. I don't cleanse between cups. If I am unsure, I go right back after the two cups about which I am confused. Pay attention to immediate reaction and don't overthink it.

Not the R&L bean, but last Friday I used a low-to-high airflow profile in a friendly Huky roasting competition consisting of 10 entries. I believe I was the only one to use the low-to-high airflow approach, and the judges ended up picking my roast as the favorite.

The competition bean was a Guatemala; I also have another Guatemala that I've been roasting off-and-on for about 5 months now. I didn't like the bean very much at first, and I would typically give the roasts of it away to others. However, now that I've been using low-to-high airflow for the past several months, it has become one of my favorite beans.

I've also noticed, on a finicky Harrar I have, that since switching to this method, it's been much easier to get the blueberry/berry flavor to appear.

In the competition, I believe most were using solid drums and I was using perforated, so that might have helped somehow. Also, I've owned the Huky for about 7 months, and I know my skill with the Huky has improved quite a bit since purchasing it too (so that would also attribute to better roasts). However, I personally believe the low-to-high airflow profile was a big factor in each of the above results.

To me, this method seems to be good at bringing out fruity, floral, and possibly other origin notes.

Really appreciate Joe and Dave sharing this method with others in their videos.