When I roast on an SR800 I tend to start with low temperatures and gradually increase temperature right into first crack (usually). So at first: high fan, low heat - low temps. From yellow on into maillard phase, less fan and more heat. At first crack I’m at the lowest fan speed and the highest heat setting. I think this is what most people do by default, in a generic sense.
Reading through recipes and roast profiles for a Bullet, it sure looks to me like the generic default roast profile is to start with the highest temperatures and decrease them throughout the roast. This is based on me looking through maybe a dozen random roast profiles. Do I understand this right? If so, why is the roasting strategy so different between a Bullet and an SR800?
Depends on what you’re trying to do. A few thoughts from someone not qualified to have an opinion about roast profiles-
a slow start with building heat will avoid scorching especially at high preheat settings; important with beans that don’t tolerate a high starting temp well
starting with a lot of heat initially is generally needed to hit 1Cs in a specific short interval with large batch sizes if you’re trying to meet certain profile targets for roast development
it’s generally easier to reduce heat throughout the roast than it is to increase (especially with a 120 VAC power board) as you have to heat the drum in order to heat the beans; a fluid bed roaster has direct transfer of heat to the beans (yeah, you have to heat the air and tranfer heat from the air to the beans, but temp change in the heating element is nearly instantaneous; not so if you have to heat a drum).
It’s a case of figuring out what you want to dofor the beans you’re roasting and how to make that happen with a drum roaster. Whatever you do, it’s more about getting most out of the beans and into the cup than it is about what the profile looks like.
Roasting in the bullet focuses more around the bean’s rate of rise (RoR). The reasoning here is that adjusting your RoR is hwo you can gauge pulling out flavors and body in the different phases of your roast.
This being said, keep in mind that, while you were roasting no more than 8oz in your SR800, you can now roast 2.2 lbs. inside the bullet. For this reason, you typically need an elevated temperature at the start to push through the drying phase. Once you’ve cleared the drying phase, the momentum of the roast has been set, meaning you don’t need the same amount of heat to keep the roast progressing.
From my experience, I do not decrease temperature throughout the entirety of the roast as a strict rule-of-thumb. I allow my RoR to shift as I feel is needed to achieve the optimal flavor and body combination.
I think that there is a very large difference between using hot air to roast beans vs. radiant and contact heat from the drum.
I’ve never heard of preheating an air roaster for 20 minutes.
With the Bullet, we mentally try to predict what power level we are going to need and at what part of the roast and we make adjustments before we get there because of the lag of the drum heating up.
With an air roaster, I believe that the hot air increases much more quickly than the drum does.
When you first start preheating the bullet, it can take 10-15 minutes to get up to the pre-heat temperature. That would probably translate into a 20 minute roast cycle. And then what are you going to do about the second roast of the day?