Lee_M Senior Member Joined: 2 Dec 2012 Posts: 42 Location: Los Angeles Expertise: I live coffee
Grinder: Baratza Encore Drip: V60 Roaster: Popper
Posted Sat Dec 8, 2012, 11:53pm Subject: Popper Roast Profile
Here's what my Air Crazy is doing, as measured by a thermometer in the bean mass. I shook the popper for the first four minutes, but otherwise left it alone. I have decoupled the fan and heater, so I have the ability to slow down the roast. Should I? If so, when? I'm pretty happy with my roasts, but they're visually not as even as I'd like. I also sometimes have trouble getting a good level of acidity without also getting underdeveloped flavors.
Coffee: Guatemala Finca Rosma First crack: 5:58 - 7:18 Batch size: 75g Popper preheated to 250F
It's difficult to write a prescription on the limited data but a few things jump out for me:
I like to see at least 3 minutes from start of first crack to finish. (didn't make that up; from Boot) This is important for roast flavor development.
Watch for when in the roast it starts to look uneven. I suspect early on as the ramp is very aggressive during what would normally be the 'drying' phase before the beans reach 300F. If you are to slow down, start here. Most who run an 'uncontrolled' popper start without any preheat. This helps to make for a more gentle start to the roast ramp.
For timing, my old rule of thumb is to allow 3-4 minutes for each of the 3 roast phases (for a total roast time of 9-12 minutes.) Drying(beans to 300F or so), Ramp to (begin) First Crack, and Finish; from start of first crack to completion. These numbers should put you in the park, but if you can't throttle the heater, it may not be possible.
I'm not familiar with the air crazy popper but I've been using a poppery 2 for a couple years on and off. I start mine without preheat and usually get first crack between 3- 4 minutes and when doing a light roast finish by 5+ minutes. The poppery 2 has a dc motor so splitting the circuits is a little more difficult. The original poppery is easy to wire the heater on the switch and the blower straight through , both are ac.
300F is about what you will see on your bean temp probe (really a composite of bean temp and air temp) The beans will have turned from green to yellow, have a grassy/steamy smell, and some expansion has already begun. After the drying phase, the smells will go from grassy to toasty. If temps are too high here, you can start the browning before all the beans have lost their 'free moisture'.
I tried following your advice. Clearly I have work to do ramping evenly with the on/off switch.
No preheat First crack: 6:50 - 10:00 (popping in the tray)
Result: flat, more roast character than I'd like, somewhat more even visually
Do you think that this is the result of early stalling, or baking during first crack? Should I be shooting for a linear rate of rise up to 300F, or quickly to say, 200F, then slower to 300F?
I don't think it's a good idea to cycle the heater on/off at all during the roast. Unless you do it very rapidly (like a PWM PID controller) you will be blowing hot and cold on the beans and this will cause more problems than it will solve. (stalling, flat, interrupted flavor development, etc)
I can't give you much specifics here with the limited info... when you say 'popping in the tray', was that first crack still going or second crack started?
First crack. I think it probably stalled out and then started again, which I suspect was the biggest problem with this roast.
I try to only switch the heater off <1 second at a time, but I think even that is too long once the temp gets up above 300F. I think my best bet at this point is to leave it alone once browning has begun, but I'm going to continue trying to gently stretch out the drying phase. Beyond that I'm not sure what I can do short of putting a Variac or PID on the heater, which I'm not ready to do yet. Once I get a kitchen timer I won't have to use my phone to keep time and I should be able to record more data via Siri. Right now I'm limited by the fact that I can't write down numbers while shaking the popper.
Maybe don't get too hung up to worry about the numbers at this point. After the drying, I look to pace the ramp between 25-33F per minute until first crack. Once first crack gets going, 5-10F per minute depending on how fast and how dark you want to go. Sounds like your taste will keep you on the lighter faster side anyway.
Looks like your first profile was better without stall during first crack. ...But I get roughed up uneven beans and harsh flavors if pushing much faster than 33F per minute during the ramp above 300F. ( my batch size is 150gr though, so this will make a difference as well.) Just keep working with what you are doing, you'll get there, Good Luck.
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