2nd Annual HB Homeroasting Competition - discussion thread - Page 20

[Gismar]

In my experience there are two ways you can get scorching/tipping in a drum roaster. It is if you charge at a to high temp. This seems highly unlikely with a kenya AA, unless it has a very low moisture content. Second is if you overdry the beans in the first phase of the roast, this combined with a long finish can tip the beans. But a kenya AA is generally very hard to tip/scorch. I have "abused" my kenyans several times, but havent seen tipping/scorching at all. If you are roasting as usual, in a way that doesnt harm other lower grown beans - my guess is you have beans with a very low moisture content.

Another thing to be aware of. The first roast of the day scorch much easier than the following roasts (with the same charge temp). Im not sure why, but I always do the first roast with a lower charge temp.

[another_jim]

Thanks, that's very useful info

[Dieter01]

1. at what temperature do you reach 1C? (so I have an idea what your reported temps are to mine)
2. what does your roast profile look like? I'm curious why you feel such a high charge temperature is needed.
3. are you using a similarly hot profile for other beans, or one unique to the Kenyas?

Here's a couple of roasts. All comments welcome
All roasts were done with fan at minimum (4) during drying, then increase to 6,5-7,5 (max is 8,5) during ramp. Minimum airflow after 1C.


This was my first roast of the day, and also my first roast of the Kenya Nyeri. Charge BT is not unlike what I use for a Kenya AA or Guatamela SHB, the charge ET is higher than normal though. I try to keep it below 280-290 (although I havn't done any tests to verify that this is important).
My interpretation: I charged at too high temperature (both BT and ET), the drying phase went too fast and the roast got away from me. Once I realized this I decided to roast darker than I normally would and see how it would do as a SO espresso. No signs of scorching but there was definitely some tipping. I don't have the cupping notes with me atm I'm afraid.



My interpretation: After roast #27 I arrived at the false conclusion that the Nyeri AB roasted much faster than my Kenya AA. I was careful during the drying phase and allowed the ET to drop too much and never really recovered. I then carried with me too much momentum into 1C and the roast was again darker than I would have liked. No signs of scorching but there was some tipping. no cupping notes (I am not at home atm).



This was the third roast of the day.
My interpretation: I decided to charge with a BT of 205 but allowed the ET to drop too much. There is a significant difference in charge ET compared to the previous two roasts that I failed to take into account properly. I tried cranking up the heat towards the end of the drying phase but it was too late. This time around I was able to drop the heat prior to 1C though.
Cupping notes: Very sweet. Fat, buttery texture. More black currant and berries than other sample yet lacking some of its refreshing acidity. 86 points.



My interpretation: Slightly more heat during the drying phase resulting in a shorter drying phase than #50. Then did a moderate ramp to 1C. Again I dropped the temp prior to going into 1C and had a controlled RoR. This roast was pretty much achieved what I was trying to do.
Cupping notes: Not as full bodied as other sample. Great acidity but probably bordering on too much. A decent cup but it should not be roasted lighter. 87 points.

The cupping was done a week after roasting. It was a direct comparison of the two Kenyas but I did not remember much about the two profiles at the time so I think its fair to call it a blind tasting.

My current plan when roasting this bean next time: Drop at BT of 210 deg and ET ~270-280. Finish drying phase in ~4 min, ramp to 1C in ~7:30 min. Then do a second batch with similar starting parameters and ramp to 1C in 8:30 min. Roast both to same level, cup and see which one is closer to a preferred roast. I need to figure out how hard these beans should e roasted between the drying phase and 1C.

[Dieter01]

This problem should affect low grown coffees like the illustrated Brazil well before it does anything to a super high grown Kenya. So if you haven't been scorching all your roasts, it's odd to have problems with just this one. I think maybe this is why Rama was asking you about the bean source.

I got my beans from Sweet Marias. Looking back I havn't roasted many lower grown coffees with the Quest. I have done a few of the SM espresso workshops, Kenyan AA and AB, Guatamala SHB, Costa Rica etc. The Nyeri AB is the first bean where I have had tipping though.

In my experience there are two ways you can get scorching/tipping in a drum roaster. It is if you charge at a to high temp. This seems highly unlikely with a kenya AA, unless it has a very low moisture content. Second is if you overdry the beans in the first phase of the roast, this combined with a long finish can tip the beans. But a kenya AA is generally very hard to tip/scorch. I have "abused" my kenyans several times, but havent seen tipping/scorching at all. If you are roasting as usual, in a way that doesnt harm other lower grown beans - my guess is you have beans with a very low moisture content.

Another thing to be aware of. The first roast of the day scorch much easier than the following roasts (with the same charge temp). Im not sure why, but I always do the first roast with a lower charge temp.

The beans were bought in November (I think) and then roasted in January. I only order beans that Tom recently acquired so I am inclined to think its not low moisture content this time. And the beans are not AA, but AB. Anyways, your comments about first batch and also overdrying w/ long finish are interesting... With my current routine I've noticed that my charge ET is usually higher on the first roast. Thats probably not related to what you are saying about first roast though but its definitely something thats different for me and that I need to look into.