What I see is that you’re not managing to slow down effectively. I might be wrong, but it looks more like a reaction rather than action roast. What I mean by that is that you’re reacting to the graph, which has a significant delay. You’re trying to slow down at the 7 minute mark, but that’s too late. Try starting with a higher fan setting and make changes sooner. Check out Coe’s recipe which you can modify to go medium, which I understand is your goal. US Champion Andrew Coe’s Light Roast Recipe - Roasting on the Bullet R1 - Roast World Community
You can also browse the forum which has various threads on Ethiopian naturals. As for the delta temp, which is the one from FC to end of roast, it is the result of what you’ve done during. As you will notice, the Coe recipe has 18% development with 8.2°C DT, while yours has 12.9°C at 18.3% and 10°C at 16.1%. That all suggests that you’re not slowing down at the right time. It isn’t so much a question of development time, as there are a number of factors. The coffee can’t be the same at the same development time if it doesn’t have the same DT. Münchow explains all this in depth in his course. I need to repeat that you must adapt and not just copy the recipe, because that one is washed and yours is a natural, along with other differences between beans and roasting environment.
first part is true, I realize that I am hesitant to react effectively as I feel it is a bit aggressive to do so (which is just subjective personal feeling which am trying to change). I will check on Coe’s recipe, but can highlight where I can do better in the graph? I would appreciate insights as am coming from commercial 5 kg gas roaster.
As for the delta temp, are suggesting mine is too high of a difference? is there an optimal delta value or some sort of reference table?
I did highlight it. At the beginning with higher fan setting, which will allow you to slow down more efficiently. On a commercial gas roaster you have the same principle. It’s not set it and forget it. As gas roasters, the Bullet has much power and the roast will run away from you if you don’t intervene at the right time. My first time on a commercial gas roaster, I was looking at the graph and backed off too late. Result? FC at 5 min and roast done at 6.
It is too high of a difference. There is no optimal delta value or a reference table. It depends on the bean and what you’re trying to do with it. As Münchow explains in his course, if you’re coming into FC steaming hot, you must cut the development time short in order to have the same colour as someone who approached it more gently. Colour is the key factor. If you haven’t already, I highly suggest taking the Münchow course, as you can learn much more there and have a better understanding of the Bullet in the shortest amount of time. I don’t know for sure, but it might still be free for Bullet users.
I can’t speak to your coffee, but I’ll say I’ve had issues in the past few years with Ethiopian coffees fading more after harvest than normal. Typically you can get coffee 12-18mo away from harvest and still have stellar results. Not so much in the past few years. Even worse, so importers have been straight relabeling or past crop blending old coffee because there was a lot left over in 2022 season. I can’t say that is the case here, but it’s possible this coffee is past it’s prime.
To your roasting question a couple thoughts: I’d recommend holding your fan constant. Either F3 or F4, just enough to get rid of your chaff, but not enough that it causes a cooling effect. When you are troubleshooting especially, eliminating any extra adjustments can help pinpoint problem areas.
Next, since you are missing the acids, I’d aim to speed up the roast. Namely, for FC to happen closer to 715-730. This will mean holding your p9 power longer before you taper power. If you hold the fan constant, you might be able to keep your power settings as they are, as the roaster is going to hold more heat.
Then increase time and temp after FC to hit the roast level you want. Medium can be subjective but I usually think that would be 212c end temp, but maybe not what you are going for. It should be possible to hit that and still be around 10ish minutes of total roast time.
Why would there be if the beans are different? The general rule is the colour you got out of it. If there were general rules, we’d all be roasting the same and getting the same good results, no matter the coffee in question.
I guess there are general rules because of physics, but the main reason I ask, is if there is no rule or trend, then why look at Delta at all? Does that make sense?
You look at it to know how far off you are from what you want. Mixed with Münchow’s graphs from the course it gives you a fuller picture. And also if you’re wondering why your roast is so dark after only 90 seconds of development, or why is it too light after 150 seconds development. It allows you to adjust your roast by knowing how far from the desired result you were. What I’m saying is that a rule is something you can apply without fault, but having so many variables you can’t make a rule. Why look at anything then? The only general rule is that it depends on the bean and what you want from it.
By the way, could you please satisfy my curiosity as to why the profiles and data in the pictures do not match those on Roast.World? I see they’re the same roasts, but the differences are noticeable. Have you changed anything post roast in the timing of the events?
I can’t speak to your coffee, but I’ll say I’ve had issues in the past few years with Ethiopian coffees fading more after harvest than normal. Typically you can get coffee 12-18mo away from harvest and still have stellar results. Not so much in the past few years. Even worse, so importers have been straight relabeling or past crop blending old coffee because there was a lot left over in 2022 season. I can’t say that is the case here, but it’s possible this coffee is past it’s prime.
I don’t think that’s the case because I tried the coffee roasted by the vendor before buying the greens and it was incredible and exotic almost like drinking juice, the coffee beans had united color before and after roasting so it is probably same harvest.
To your roasting question a couple thoughts: I’d recommend holding your fan constant. Either F3 or F4, just enough to get rid of your chaff, but not enough that it causes a cooling effect. When you are troubleshooting especially, eliminating any extra adjustments can help pinpoint problem areas.
Next, since you are missing the acids, I’d aim to speed up the roast. Namely, for FC to happen closer to 715-730. This will mean holding your p9 power longer before you taper power. If you hold the fan constant, you might be able to keep your power settings as they are, as the roaster is going to hold more heat.
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