What is a good preheat temp for JBM?

I bought 5 pounds of Jamaican Blue Mountain peaberry, and have roaster two 1 lb batches, so far. Both roasts have a burnt flavor, which is detrimental to JBM. I preheated to 180 the first time, and roasted P7F4 to 8:00 176C, then P5F5 to drop at 11:20 194C. The second batch preheated to 170, P8F4 to 8:00 160C, then P6, 5, 4 F5 to drop at 12:22 185C. I will try a more traditional fan setting next time, but what preheat temp would you suggest for 454gr peaberry?

Hey man,

I don’t have a bullet r1 yet (still hasn’t come to Australia yet :face_with_symbols_over_mouth:). However I do roast coffee 3-4 days a week for a company and want to offer some things I have found useful.

  1. Rate of rise (ROR) is key to minimising burnt flavours, try to minimise the amount of flicks in the ROR and keep it always declining, not sure if that’s what you already are doing. Everytime it rises substantially it will create burnt flavours, whereas if it crashes(drops substantially very quickly, particularly around FC) it will create baked (reduced juiciness and sweetness, hollow) flavours.

  2. check for adequate airflow. I like to use the lighter test where during a roast you pull out the tryer and hold a naked flame infront of the hole:
    if the flame is extinguished it means to much airflow at that point in the roast

    If the flame leans gently towards the hole it usually means the airflow is adequate at that point in time.

    If the flame doesn’t really lean at all toward the hole then the airflow is inadequate at that point in time.

Inadequate airflow will cause smoky flavours even in light roasts. This is because the Chaff isn’t being drawn out of the drum and is sitting, burning and smoking, creating the smoky flavours. However smoky flavours can also be from darker roasting too.

If you need me to clarify anything just ask.

Hope this helps you

Thank you for the speed course. It is always good for home roasters to talk to each other and review what should be elementary. The Bullet is the first roaster I have had on which preheat temperature can be set, and set so accurately. Without a cadre of fellow Bullet roasters to sit around and chat with, I am still struggling to fully understand the effects of preheat temperature.

To answer your initial question. It doesn’t sound like it’s a preheat temperature question because you said your second roast went for 12:22 which seems long enough for your 50% capacity roast. If your roast was very fast you might get some burnt flavours, but that roast time seems adequate.

I think if you look at the other things I mentioned and maybe consider ending the roast at a lighter degree still?

YasBean I am having difficulties with roasting the JBM for the right taste. Have you figured out a good recipe any help would be tremendous!!
Thank you

I have found that hitting the bean with a LOT of heat, works best. For 350g. batches, here is my roast curve. This is for Kona, which is a soft bean similar to Jamaica. Interestingly, this recipe works very well for hard beans, as well. I’ll post the same recipe for a Guatemala gesha bean. Just dump the beans in QUICKLY, and you won’t scorch or tip them. I’m experimenting with a P0 “soak” until t=45sec. to also minimize the tipping or scorching possibility. But the results so far have been really encouraging.

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thank you for sharing matilsky!!

If you try something similar to this recipe, let us know how it turns out!

@bodyklense I have not had JBM or Kona in quite a while.
@matilsky Thank you for your recipes, I will refer to them the next time I pick up some Kona.

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@matilsky tried your idea of hitting it with a higher temperature and it definitely did help with the flavour. Thank you very much!! I will post it up once I get the hang of it as I was just experimenting with the heat

I have maybe 20 or 30 lbs of JBM laying around. I use to try a gentle profile, similar to Ethiopia coffees, with mixed results. It’s such an expensive bean to experiment with that I gave up. I’ll try a higher charge temp, like I would use for Latin america coffee, and see how that works out.

Don’t give up, experimenting is better than letting the coffee get too old.

after cupping this batch, I must say 'm very happy!!! considering these beans were from the 2018 harvest.